Evaluation of the Performance of the Xm759 Logistical Carrier

TECHNICAL REPORT NO. 3-808

EVALUATION OF THE PERFORMANCE OF THE XM759 LOGISTICAL CARRIER

B. 6. Schreiner A A Rula

January 196&

Sponsored by U. S. Army Materiel Command

Conducted by u. S. Army Engineer Waterways Experiment Station CORPS OF ENGINEERS Vicksburg, Mississippi

This document is subject to special export controls and each transmittal to foreign governments or foreign nationals may be made only with prior approval of U. S. Army Materiel Command. TECHNICAL REPORT NO. 3-808 j~y-,;v( J EVALUATION OF THE PERFORMANCE OF THE XM759 ~O~~S!~iL..~aBB.lg~j' by

B. G. Schreiner A. A. Rula

January 1968

Sponsored by " i U. S. Army Mat:eriel Command \ \ -",----: '- ~,,----

Conducted by U. S. Army Engineer Wat:erways Experiment: St:at:ion CORPS OF ENGINEERS )." . ,/ Vicksburg, Mississippi

ARMY-MRC VICKSBURQ. MISS.

rThis document is subject to special export controls and each transmittal to foreign governments or foreign nationals may be made only with prior approval of U. S. Army Materiel Command. THE CONTENTS OF THIS REPORT ARE NOT TO BE USED FOR ADVERTISING, PlffiLICATION, OR PROMOTIONAL PURPOSES. CITATION OF TRADE NAMES DOES NOT CONSTITUTE AN OFFICIAL EN DORSEMENT OR APPROVAL OF THE USE OF SUCH COMMERCIAL PRODUCTS.

iii FOREWORD

A development program for the XM759, 1-1/2-ton Logistical Carrier, Amphibious, was requested by the Commandant of the U. S. Marine Corps (USMC) in February 1965, and the U. S. Army Materiel Command (AMC) was designated as monitoring agency. AMC subsequently designated the U. S. Army-Tank Automotive Command (ATACOM) as the action agency. The study reported herein was a part of the development program and was conducted as a joint effort by ATACOM, the General Equipment Test Activity (GETA), and the U. S. Army Engineer Waterways Experiment Station (WES). The study was conducted during the period from(October 1966 to July 1967: Acknowledgments are made to MAJ S. G. Tribe and MAJ L. J. Trembley, USMC Headquarters, who participated in numerous planning meetings and observed the field test programs; to Mr. James Carr, AMC project manager for his coordinating efforts and general guidance; to ATACOM personnel, particularly Messrs. J. Tannenbaum, R. E. Nette, and V. J. Kowachek, for assistance and guidance in programming; and to GETA personnel, partic ularly Messrs. S. DeStefano and G. B. Penn, for their support and co operation in conduct of the field program. WES participation in the study was under the general direction of Messrs. W. J. Turnbull, Technical Assistant for Soils and Environmental Engineering, W. G. Shockley, Chief, Mobility and Environmental (M&E) Division, S. J. Knight, Assistant Chief, M&E Division, and A. A. Rula, Chief, Vehicle Studies Branch. Field tests and data analyses were con ducted by personnel of the Soil-Vehicle Studies Section under the direc tion of Mr. E. S. Rush, Chief, and Mr. Penn, GETA. Field tests were under the direct supervision of Mr. B. G. Schreiner, Soil-Vehicle Studies Section, and Mr. Duncan, GETA. This report was prepared by Messrs. Schreiner and Rula. Appendix C was written by

v Mr. W. K. Dornbusch, Jr., Geology Branch, WES. Director of the WES during the conduct of this study and preparation of this report was COL John R. Oswalt, Jr., CEo Technical Director was Mr. J. B. Tiffany.

vi CONTENTS

FOREWORD ..•... v CONVERSION FACTORS, BRITISH TO MErRIC UNITS OF MEASUREMENT. ix SUMMARY ...... xi PART I: INTRODUCTION 1 Background 1 Purpose. . 2 Scope. .. 2 Previous Studies of Pneumatic Track Vehicles 3 Definitions. .. 3 PART II: TEST VEHICLES ...... • 9 Pertinent Vehicle Characteristics. 9 XM759 Propulsion System. 9 PART III: TEST PROGRAM .•...•.• 12 Selection, Location, and Description of Test Sites 12 Test Procedures and Data Collected 24 PART IV: ANALYSIS OF DATA. • 30 Trafficability Tests . 30 Mobility Tests •..••••• 42 Notes and Observations . 47 PART V: EVALUATION OF PERFORMANCE OF VEHICLES. 50 Comparison of Trafficability Test Results. 50 Comparison of Mobility Test Results.... 56 PART VI: SUMMARY OF TEST RESULTS .AND REr;OMMENDATIONS .• 57 Summary of Test Results. 57 Recommendations .•... 59 TABLES 1-11 PLATES 1-24

vii APPENDIX A: DETERMINATION OF VEHICLE CONE INDEXES FOR TRACKED VEHICLES. Al Fine-Grained Soils . Al Organic Soils ••• A3 TABLE Al APPENDIX B: EFF:EDTS OF SOFT SOIL BOOYANCY ON VEHICLE CONE INDEX DETERMINATION .....••• •• •.• •. Bl Introduction •...•••.•.•.• Bl Volume and Weight Computations ••.•. B2 Buoyancy Effects on VCI Determination. B5 PLATES Bl and B2 APPENDIX C: COMPARISON OF TERRAIN TYPES. Cl Background ••••••.•••. Cl Terrain Factors..•••.••.••• c4 Development of Analog Criterion. ••••.• C7 Comparison of Mekong Delta and Mississippi River Delta Terrain Types...... c8 Comparison of Mekong Delta and Mobility Test Course Terrain Types...... c8 TABLES Cl and C2

viii CONVERSION FACTORS, BRITISH TO MErRIC UNITS OF MEASUREMENT

British units of measurement used in this report can be converted to metric units as follows:

Multiply By To Obtain

inches 2.54 centimeters square inches 6.4516 square centimeters feet 0.3048 meters cubic feet 0.0283168 cubic meters pounds 0.45359237 kilograms pounds per square inch 0.070307 kilograms per square centimeter pounds per cubic foot 16.0185 kilograms per cubic meter tons 907.185 kilograms miles 1.609344 kilometers miles per hour 1.609344 kilometers per hour square miles 2.58999 square kilometers

ix SUMMARY

The XM759, 1-1/2-ton Logistical Carrier, Amphibious, was tested at five sites in Virginia and eight in Louisiana on a wide range of terrain conditions analogous to those of the Mekong Delta of South Vietnam. The off-road performance of the XM759 was compared with that of an Ml16, 1-1/2-ton Cargo Carrier, Amphibious, on the same test sites. The purpose of the test program was to (a) identify terrain conditions commonly found in the Mekong Delta and to locate analogous terrain in the United states that could be used for vehicle tests; (b) determine the.o.f.f.-...... rQ§W~it~rILance of the XM759 and the ..!11J,Q. on a wide range of terrain con- "ditions occur!i;g in wet, deltaic marshlands; (c) describe in d@iall the terrain on which vehicle tests were conducted; and (d) evaluate the com parative performances of the XM759 and Ml16 on similar terrains., Trafficability tests were conducted on level terrain to determine (a) the minimum soil strength, in terms of rating cone index (RCI), re (VCI~) quired for the vehicles to complete one pass and 50 passes (VCI sO ); (b) drawbar pull-slip relations for a range of sOlI strength condition~ and vegetal covers; (c) drawbar pull-strength relations on a variety of surface vegetation; (d) the effect of soil strength and vegetal cover on vehicle turning radius and speed; and (e) the maximum step height negoti able in exiting from bodies of water. Mobility tests were conducted to determine the average maximum safe speed while traversing straight-line test courses that included more than one type of terrain in each traverse. Tests were conducted with empty vehicles and with vehicles loaded to 100% and 200% pay loads in 47 types of terrain. Of the 44 mobility test course terrain types used in the development of analog criterion, 16 were highly analogous to one or more terrain types identified in the Mekong Delta, 14 were analogous, 12 were moderately analo gous, and 2 were slightly analogous. For the six soft-soil areas selected in the Mekong Delta, it is estimated that the XM759 with 100% pay load can traverse 100% of the areas for 50 passes, whereas the Ml16 with the same pay load can traverse only 89% of these areas for one pass and only 61% for 50 passes. The XM759 with 100% and 200% pay loads completed 50 passes on a soil strength as low as 2 RCI. The Ml16 with 100% pay load completed one pass on a soil strength of 7 RCI and 50 passes on 14 RCI. The experimental VCII at 100% pay load for the XM759 was considered to be zero. The pneumatic

xi tires and sponson of the XM759 provide buoyancy when they are immersed in soft, viscous soils, thereby reducing the effective weight of the vehicle. Closer agreement between experimental and computed VCI's can be achieved by considering the effect of buoyancy. r;he maximum draWb~~ull of both vehicles at 100% pay load was limited because of lnsu~ci~~t power to develop sufficient force to shear the soi~ On an RCI of about 75, the XM759 developed a maximum traction coefficlent (TC) of 0.64 when empty and 0.49 with 100% pay load. On the same RCI, the Ml16 developed a maximum TC of 0.89 when empty and 0.75 with 100% pay load. On an RCI of about 7, the XM759 developed a maximum TC of 0.27 with 100% pay load. On the same RCI, the empty Ml16 was barely able to propel itself. For all vehicle weights tested, the motion resistance coefficient for the XM759 was 0.18 and 0.07 at RCI's of 4 and 75, respectively. For the same RCI's, the Ml16 developed a motion resistance coefficient of 0.34 and 0.14, respectively. Maneuver test results were not as definite as results of other per formance tests; however, general trends indicate that the XM759 at 100% pay load was capable of negotiating turns of slightly shorter radii than the Ml16 on RCI's between 40 and 8. On RCI's less than 8, the Ml16 could not negotiate turns; the XM759 negotiated turns on RCI's between 8 and 2 with a great increase in turning radius for a small decrease in soil strength. Data indicate that the 0059 can negotiate tighter turns on soil strengths between an RCI of 12 and 40 than it can on pavement. The XM759 and Ml16 at 100% pay loads negotiated-maximum step heights of 2.2 and 2.8 ft, respectively. Mobility tests were conducted with the XM759 on 47 terrain types and the Ml16 on 35 terrain types. The 0059 negotiated 46 and the Ml16 negotiated 26 terrain types. First-pass speeds ranged from 10.23 to 2.08 mph for the 0059, and from 11.25 to 2.22 mph for the Ml16. Of the 15 mobility test courses, the 0059 negotiated 14 courses and the Ml16 only two. First-pass speeds ranged from 11.18 to 2.56 mph for the 0059 and from 12.18 to 2.86 mph for the Ml16. 'An evaluation of the comparative performances of the XM759 and Ml16 in terms of the terrain-vehicle relations (traf· .. .e~) and average speed for the terrain types tested ( ~~ shows that the performance of the XM759 exceeded that 0 for most of the terrain conditions tested. j . _I I- , Appendix A shows the computations necessary for the determination of vehicle cone indexes of tracked vehicles. Appendix B presents a method for determining the effects of buoyancy on vehicle cone indexes. Appendix C presents the results of the terrain evaluation study conducted to identify terrain types in several sections of South Vietnam and to locate similar areas in the Mississippi River Delta for vehicle test purposes.

xii EVALUATION OF THE PERFORMANCE OF THE XM759 LOGISTICAL CARRIER

PART I: INTRODUCTION

Background

1. In February 1965 the Commandant of the U. S. Marine Corps (USMC) requested that the U. S. Army Materiel Command (AMC) conduct a develop ment program for a Marginal Terrain Vehicle, 1-1/2-ton* (MTV), later desig nated the XM759, 1-1/2-ton Logistical Carrier, Amphibious. The USMC spe cifically requested that the vehicle incorporate a low-pressure pneumatic tired track system. In subsequent meetings and correspondence, AMC agreed to conduct the development program and designated the U. S. Army Tank Automotive Command (ATAC) as the action agency. 2. In July 1966, the U. S. Army Test and Evaluation Command issued a test directive for the conduct of engineering tests of the XM759, and assigned primary responsibility for these tests, including mobility off road performance tests, to the U. S. Army General Equipment Test Activity (GETA). AMC requested that the U. S. Army Engineer Waterways Experiment Station (WES) participate in the preparation of test plans and selection of test areas, emphasizing that, in the selection of test areas, consid eration be given to determination of performance of the XM759 in terrain conditions analogous to those of the Mekong Delta of South Vietnam. 3. During October 1966-February 1967, WES and GETA personnel rec onnoitered potential test sites in the Virginia wetlands and the Mis sissippi Delta and selected specific areas for testing. On 23 March 1967, representatives of all agencies participating in the XM759 development program met at Fort Lee, Va., for a final review of the engineering and service test plans. Plans for a mobility test, to be conducted as part of the engineering tests, were discussed. Information was presented con cerning the basis for selecting the test sites, methods used in

* A table of factors for converting British units of measurement to metric units is presented on page ix.

1 collecting data to adequately describe terrain for ground mobility pur poses, and results of tests made during the reconnaissance. Information was also presented on test schedules, types of tests to be conducted, data to be collected, test procedures to be followed, relations to be sought, field operation plans, and final report. The representatives of the par ticipating agencies approved the mobility test plan.

Purpose

4. The purpose of the test program was to: (a) conduct a study to identify terrain conditions commonly found in the Mekong Delta and to lo cate analogous terrains in the United States that could be used for vehi cle tests, (b) determine the off-road performance of the XM759 and an Ml16 on a wide range of terrain conditions occurring in wet, deltaic marshlands, (c) describe in detail the terrain on which vehicle tests were conducted, and (d) evaluate the comparative performances of the XM759 and Ml16 on similar terrains.

Scope

5. Tests were conducted with the XM759 and Ml16 at five sites in Virginia from mid-April to early June 1967, and at eight sites in south Louisiana from mid-June to mid-July 1967. Trafficability tests (see def initions, paragraph 8) were conducted on level terrain to determine: (a) the minimum soil strength required for the vehicles to complete 1 and 50 passes, (b) drawbar pull-slip relations for a range of soil strength conditions and vegetal covers, (c) drawbar pull-strength relations on a variety of surface vegetation, (d) the effect of soil strength and vegetal cover on vehicle turning radius and speed, and (e) the maximum step height negotiable in exiting from bodies of water. Mobility tests were conducted to determine the average maximum safe speed while traversing straight-line test courses that included more than one terrain type in each traverse. Tests were conducted with zero pay load, 100% rated pay load, and 200%

2 rated pay load. Tests were conducted in 47 types of terrain.

Previous Studies of Pneumatic Track Vehicles

6. In October 1960 and March 1961, WES conducted tests with an Airoll test bed in Michigan in organic and sandy soils and in Missis sippi in fine-grained soils.* The Airoll test bed was designed and fab ricated by Ingersoll-Kalamazoo Division of Borg-Warner Corporation under the Office of Naval Research Contract NOrn-2459(00). Among other things, the test results indicated that the test bed utilizing the pneumatic tracks as traction elements could travel over very soft muck and wet, fine-grained soils that no known military vehicle of equal weight (19,000 Ib) could negotiate. 7. In 1962, several vehicles with pneumatic track systems were built for the USM::: and designated the LVAXl. The curb weight of the LVAXI was 5900 Ib, and the total pay load was 1/2 ton. In August 1964, WES conducted a limited number of tests with the LVAXI in organic terrain near Parry Sound, Ontario, Canada.** In these tests this vehicle per formed better than conventional tracked carriers on extremely soft terrain. The LVAXI could easily exit or enter open water that was surrounded by dense, nonwoody, floating vegetation mats.

Definitions

8. Certain special terms used in this report are defined below. General terms Ground mobility. The ability of a ground contact vehicle to move across a landscape without benefit of roads or engineering assistance.

* E. S. Rush and A. A. Rula, "Trafficability Tests with the Airoll on Organic and Mineral Soils, II Miscellaneous Paper No. 4-439, August 1961, U. S. Army Engineer Waterways Experiment Station, CE, Vicksburg, Miss. ** E. S. Rush, "Trafficability Tests on Confined Organic Terrain (Muskeg); Summer 1964 Tests," Technical Report No. 3-656, Report 3, U. S. Army Engineer Waterways Experiment Station, CE, Vicksburg, Miss. (in preparation).

3 Thus, a measure of ground mobility is a measure of the vehicle-terrain interaction. Trafficability test. A test conducted in a homogeneous area at low speeds to determine vehicle-terrain relations. Mobility test. A test to determine vehicle performance in terms of average speed over a straight-line course covering several terrain types. In a mobility test the driver is instructed to drive as fast as practica ble, consistent with safety to himself, the vehicle, and the cargo. Soil terms Unified Soil Classification System (USCS).* A soil classification system based on identification of soils according to their textural and plastic Qualities and on their grouping with respect to engineering behavior. Fine-grained soil. A soil of which more than 50% (by weight) of the grains will pass a No. 200 U. S. Standard Sieve (smaller than 0.074 mm in diameter). Coarse-grained soil. A soil of which more than 50% (by weight) of the grains will be retained on a No. 200 sieve (larger than 0.074 mm in diameter). Organic soil. The living, dying, and dead vegetation that forms a surface mat, and the mixture of partially decomposed and disintegrated organic material (commonly known as peat or muck) below the surface mat. Small Quantities of mineral soil mayor may not be mixed with the organic material. Consolidated (nonfloating) organic soil. Consolidated organic soils consist of two components. The first includes the aerial portion (vegetal cover) and a large part of the subaerial portion (roots, rhizomes, etc.) of a living layer of organic terrain. The second component is the under lying true fossilized peat. Both components are highly compressible and have high rebound characteristics.

* U. S. Department of Defense, "Unified Soil Classification System for Roads, Airfields, Embankments, and Foundations," MIL-STD-619A, 20 March 1962, U. S. Government Printing Office, Washington, D. C.

4 Unconsolidated (floating) organic soil. Unconsolidated organic soils consist of two components. The first is a vegetal mat (Similar to the vegetal mat described above) that "floats" upon the second com ponent, which usually is water with a negligible quantity of solid parti cles but which, on occasion, has been found to be peat in a fluid or nearly fluid state. Critical layer. The layer of soil regarded as most pertinent to establishing relations between soil strength and vehicle performance. For 50-pass tests in fine-grained soils and sands with fines, poorly drained, it is usually the 6- to 12-in. layer; however, it may vary with weight of vehicle and with soil strength profile. For l-pass tests it is usually, but not always, closer to the surface. Soil strength terms Bearing capacity. The ability of a soil to support a vehicle without undue sinkage. Traction capacity. The ability of a soil to provide sufficient resistance to the tracks or wheels of the vehicle to furnish the necessary thrust to move it forward. Cone index (CI). An index of the shearing re sistance of a medium obtained with a cone penetrome ter (shown in fig. 1). The value represents the re sistance of the medium to penetration of a 30-deg cone of O.5-sq-in. base or projected area. The num ber, although usually considered dimensionless in trafficability studies, actually denotes pounds of force on the handle divided by the area of the cone base in square inches. Remolding index (RI). A ratio that expresses the proportion of original strength of a medium that will remain under a moving vehicle. The ratio is de termined from cone index measurements made before Fig. 1. Cone and after remolding a 6-in.-long sample using the penetrometer

5 equipment shown in fig. 2. The test sample is obtained with a traf ficability sampler (shown in fig. 3).

Fig. 2. Remolding equipment Fig. 3. Trafficability sampler and cone penetrometer

Rating cone index (RCI). The product of the measured CI and the RI of the same layer. Shear stress, peak. The greatest shear stress recorded when torque is applied to the sheargraph head during initial soil failure for a par ticular normal stress maintained on the sheargraph handle. (The shear graph, shown in fig. 4, is a hand-operated instrument utilizing a coiled spring system for measuring torque and load.) Shear stress, ultimate. The greatest shear stress recorded during the continued rotations of the sheargraph head after initial soil failure for a particular normal stress maintained on the handle.

6 Terrain terms Terrain terms are defined in Appen- dix C. Vehicle terms Immobilization. The inability of a self-propelled vehicle to go forward or backward. Pass. One trip of the vehicle over a test course. Multiple passes. More than one pass of the vehicle in the same path over the test course. Mobility index (MI). A dimension less number that results from a consideration of certain vehicle characteris tics. It is used to obtain an estimate of the VCL Vehicle cone index (VCI). The min imum rating cone index (RCI) that will permit the vehicle to complete a speci fied number of passes; thus, VCI means SO the minimum ReI necessary to complete Fig. 4. Cohron sheargraph SO passes, and VCIl means the minimum RCI necessary to complete one pass. Maximum drawbar pull. The maximum amount of sustained towing force a self-propelled vehicle can produce at its drawbar under given test conditions. Towed force. The amount of force required to tow a given vehicle in neutral gear under given test conditions. Total tractive effort. The maximum towing force or drawbar pull de veloped by a vehicle plus the force required to tow it (in neutral gear) under given test conditions. Tractive coefficient (TC). The ratio of the drawbar pull to the gross weight of a vehicle under given test conditions.

------Slip. The percentage of track or wheel movement ineffective in thrusting the vehicle forward. Motion resistance coefficient (RC). The ratio of the towed force to the vehicle weight under given test conditions.

8 PART II: TEST VEHICLES

Pertinent Vehicle Characteristics

9. Characteristics of the XM759 and the Ml16 as furnished by ATAC are given in tables 1 and 2, respectively. Because of the unique propul sion system of the XM759, a discussion of its concept of locomotion is presented herein. other pertinent characteristics of the vehicles that are not adequately covered in tables 1 and 2 are given below. (The values below differ slightly from those in tables 1 and 2 because of the differences between individual vehicles.)

Vehicle Characteristics XM759 Ml16 Empty weight, lb 10,000 7,600 Loaded weight, lb (100% pay load) 13,000 10,600 Loaded weight, lb (200% pay load) 16,000 Ground contact pressure, psi Empty 1.25* 1.94 100% pay load 1.62* 2.70 200% pay load 2.00* Height of driver's eye above ground when vehicle is on hard surface, ft 8 5.7 Tire inflation pressure, psi 15

* Based on projected contact length of center-line dis tance between front and rear sprockets and width of tires.

XM759 Propulsion System

10. The track system is composed of free-rolling, low-pressure, pneumatic tires mounted on endless chains rotating about driving sprockets and return idlers. The track is supported on top and bottom by a sponson. The track system is rigid except that deflection of the tires occurs underneath the sponson. In operation, the chains move the tires to the ground in front of the sponson, and the sponson then moves over the tires. Movement of the XM759 can occur in two different and distinct types of action of the tires on the ground: rolling-wheel track action and

9 stationary-wheel track action. Various combinations of the two actions also can occur, Rolling-wheel track action 11. When the XM759 operates on a level or moderately sloping firm surface, the tires are made to roll beneath the sponson by the tangen tial force being applied by the bottom of the sponson, as illustrated in fig. 5. In rolling-wheel track action the friction force (f) between the

A =POINT ON SPONSON a = POINT ON TIRE d = EFFECTIVE TIRE DIAMETER

1--.. ---lTd TIRE ROLLS WHEN f 1-....------2ITd ------.,:I IS GREATER THAN I r + r' Fig. 5. Rolling-wheel track action sponson and the tires is greater than the total rolling resistance between the tires and the ground. The total rolling resistance is defined as the resistance caused by friction between the tires and the ground (r) plus that caused by the deformation of the ground (r'). In the rolling-wheel state, relative motion occurs between the chain (connecting the tires) and the ground. Each tire rotates on its own axis. If it is assumed that no slip occurs between the tires and the sponson or ground, in one revolu tion of a tire the sponson moves through a distance equal to twice the rolling circumference of the tire. Stationary-wheel track action 12. In stationary-wheel track action, the XM759 moves in a manner similar to that of a conventional tracked vehicle, i.e. the tires of the XM759 are carried forward by movement of the chain (track) around the sprocket, reach the ground, and remain in contact with the ground at the same place while the XM759 moves ahead. The tires themselves may rotate in place or remain stationary. They rotate in place when the frictional force between the sponson and the tire is greater than the friction be tween the tire and the soil but less than the total resistance (see fig. 6).

10 TIRE ROTATES IN PLACE WHEN f IS GREATER THAN r BUT LESS THAN r + r'

Fig. 6. stationary-wheel track action, tire rotating in place This condition occurs only occasionally when the soil surface is wet and slippery. The tires neither roll nor rotate when the force between the sponsons and the tire is less than that between the tire and the ground (see fig. 7). This condition usually occurs when rutting is relatively great.

TIRE NEITHER ROLLS NOR ROTATES WHEN r + r' IS GREATER THAN f

Fig. 7. Stationary-wheel track action, tire neither rolling nor rotating

Immobilization 13. Immobilization occurs when the force necessary to move the XM759 is greater than the shearing resistance of the soil; the tires are forced to slide beneath the sponson, shearing the soil as they slide (fig. 8). In such a case of 100% slip, the tires usually do not rotate. .. FORWARD DIRECTION

Fig. 8. Immobilization, tire sliding rearward

11 PART III: ,TEST PROGRAM

Selection, Location, and Description of Test Sites

Selection 14. In the selection of test areas, especially in south Louisiana, consideration was given to determination of vehicle performance in ter rain conditions analogous to the Mekong Delta. Reports and soil maps of six areas of the Mekong Delta were studied to determine the terrain types that probably exist there and results of this study were used for guid ance in selecting vehicle test sites in the United States (Appendix C). Terrain factors considered in selecting analogous test areas were, primarily, surface geometry, vegetation, and soil strength. The areal occupancy of terrain conditions was also considered in site selection. Location 15. Test sites were selected in the southeast coastal region of Virginia and the south-central coastal region of Louisiana. General lo cations of the sites are shown in figs. 9 and 10. The number within each area outlined by a heavy boundary line is the site number.

Fig. 9. General location of Virginia test sites

12 ui '"\

Ak:hafalaya Bay

N""h Poinl

"""Bay Fig. 10. General location of Louisiana test sites

Description 16. General test site descriptions are given in the following para graphs. To assist in site description, surface profiles, vegetal cover, soil strength in terms of CI and RCI, and photographs of the mobility test courses are shown in plates 1-7. It should be noted that the height of *' all vegetation except trees and shrubs greater than 10 ft high are shown to scale in the plates. Vegetation greater than 10 ft in height occurred at site 4 (plate 3) and site lOA (plate 7). 17. Appomattox River, Va., site 1. This test site (fig. 11) is approximately 2 miles northeast of Petersburg on the Appomattox River. The site contains a small, bare, tidal mud flat and a slightly higher soft river terrace. At the time of testing, the terrace area was covered with grasses and some cattails. The site was utilized for mobility and traffic ability tests. A surface profile and photographs of the mobility test course are shown in plate 1.

13 Fig. 11. Appomattox River, Va., site 1

18. Camp Wallace, Va., site 2. Site 2 (fig. 12) is on the south east section of Camp Wallace. It is a depressed, confined, organic bog with a drainage outlet to the James River. Surface water level is in fluenced by tidal action. This site consists of soft, highly organic soil covered with tussocks of wire and marsh grass, with some reed cane concentrated in spots. Mobility and trafficability tests were conducted at this site. Plate 1 shows a surface profile and photographs of the mobility test course. 19. Chickahominy River, Va., site 3. The Chickahominy site (fig. 13) is approximately 2 miles upstream from Walker's Dam in the shallow areas of the reservoir formed by the dam. The site surface is partially covered with organic sediment and vegetation. The test courses included sections of tussocks and clumps of marsh grass and floating water hyacinths anchored to the bottom by an extensive system of roots 3 to 4 in. in diameter. This site was used for mobility and

14 Fig. 12. Camp Wallace, Va. site 2

\ \ \ , "\ , SCALE" 1:25,000 \

F19." 13 . Chickahominy River, • Va., site 3 trafficability tests. Surface profiles and photographs of the mobility test courses are given in plate 2. 20. Mulberry Island, Va., site Site 4 (fig. 14) is located on ····~t - G i

Heliport

ntrol Ner ng Strip ~ ~ SCALE ~:_2~~5l0J~ -'- ,/ Fig. 14. Mulberry Island, Va., site 4

the Ft. Eustis military reservation in the floodplain of the Warwick River. The mineral soil types comprising the site are fat and sandy clays, and in low places they are covered with organic material. The slightlyundu lating site surface is covered by a wide range of vegetation types, with needlegrass and marsh grass and tussocks occupying the swales and large pine trees with a dense understory of scrub growing on the ridges. Mobil ity and trafficability tests were conducted at this site. Plate 3 shows a surface profile and photographs of the mobility test course. 21. Messick, Va., site 5. This site (fig. 15) is located in a

16 marsh adjacent to the Back River about 1-1/2 miles southeast of Messick, Va. The surface is composed of firm, highly organic soil; the height and density of the grasses were uniform throughout the site. Mobility and trafficability tests were conducted here; the mobil Co. " ity test course included four drainage ways. A surface profile and photo graphs of the mobility test course are given in plate 3. 22. Bonnet Carre, La., sites 6 2 and 6A. Site 6 (fig. 16) is approxi mately 3 miles north-northeast of - 2; Norco, La., in the Bonnet Carre Flood A~Orys Wharf J'L, / way. The soil is firm organic clay. / \ 0 Piling //, Surface water level is affected by ) \ /// .... 1I tidal action. The surface was covered ~ //lighty_1 / / ""if( _'_ QJ/ mostly with alligator grass and vari Fig. 15. Messick, Va., site 5 ous other nonwoody plants. Mobility and trafficability tests were conducted at this site. Site 6A is about 1 mile southwest of site 6, and it was similar to site 6 except that the area was covered with a dense growth of wax myrtle and ragweed. This site was used for mobility tests only. Plate 4 shows surface profiles and photographs of the mobility test courses. 23. Beauregard Island, La., site 7. Beauregard Island (fig. 17) is 1 mile north of Grand Isle, La. The site has a variety of soils, includ ing sand, clay, and organic clay. Tidal action influences the depth of surface water on the island. Both vegetated and bare areas occurred with in the test site. Vegetation varied from tall reed cane to low marsh grasses. More trafficability and mobility tests were run at this site and at Bayou du Large, La., site 8 (see following paragraph), than at the other sites; therefore a detailed layout of the test course for this site is shown in fig. 18. Surface profiles and photographs of the

17 -7

Fig. 16. Bonnet6 ndCarre,6A La. , sites a

/3 INI /. /.

Fig. 17. Beauregard Island, La. , site 7 Fig. 18. Layout of test courses, Beauregard Island, La., site 7

19 mobility test courses are shown in plate 5. 24. Bayou du Large, La., site 8. This test site (fig. 19) is

:'- - SCALE I CAILLOU LAKE I., :62.500 'I Fig. 19. Bayou du Large, La., site 8 southwest of Houma, La., and approximately 6-1/2 miles from the termina tion of State Highway 315. Site 8 has a wide range of soil strengths and terrain types. Tidal action influences the depth of surface water. Bayou du Large is bordered by 200-ft-wide sections of clay soil with some organic material. Organic soils and areas of floating mat adjoin the clay sections. Mobility and trafficability tests were conducted in the wide variety of terrain types at this site (see fig. 20). Plate 6 shows the surface profile and photographs of the mobility test course. 25. Minors Canal, La., site 9. Site 9 (fig. 21) is 4 miles north west of the intersection of Bayou du Large and Falgout Canal. Minors Canal is flanked by low berms of highly organic soil. Extensive areas of vegetal mat floating on water adjoin the berms. The vegetation was

20 I\) I-'

SCALE IN FEET 500 0 500 -- LEGEND- I VCI VEHICLE CONE INDEX TESTS DBP ORAWBAR PULL AND TOWED TESTS NOTE: NUMBERS DESIGNATE TEST NUMBERS.

Fig. 20. Layout of test course, Bayou du Large, La., site 8 Fig. 21. Minors Canal, La., site 9 primarily alligator and marsh grasses with areas of dense cane. Only mobility tests were conducted at this site. The test course crossed Minors Canal at right angles. Plate 6 shows the surface profile and photographs of the mobility test course. 26. Morgan's Island, La., sites 10 and lOA. Site 10 (fig. 22) is 4 miles upstream from Morgan City, La., on the Atchafalaya River. Depth of surface water at this site is affected by tide, wind direction, and river stage. Soils encountered at the site were sandy clay, silty clay, and organic clay. Vegetation included lily pads, small willow trees, and alligator and marsh grasses. Mobility and trafficability tests were conducted at site 10. Site lOA was similar to site 10 except that it

22 -3 15 1· SIX - . :J·1i -, -3 -, L

DOG 22 ISLAND

Island 'IX-2 MILE

-3

-2LAKE

Fig. 22. Morgan's Island, La., sites 10 and lOA

was covered with a uniform stand of willow trees 20 ft high. This site was used for a mobility test. Surface profiles and photographs of the mobility test courses are given in plate 7. 27. Chicken Island, La., site 11. Site 11 (fig. 23) is 14 miles south of Morgan City, La., on Big Wax Bayou. Surface water level is affected by tide, wind direction, and Atchafalaya River stage. Soils at the site are silty clay and highly organic clay. Two drainageways tra versing the area were flanked with dense growths of elephant-ear-type vegetation. Other vegetation at the site included alligator grass and cane. This site was used for mobility tests only. Plate 7 shows the surface profile and photographs of the mobility test course.

23 18

-J.J -0.6" L& tJ80+00 j

Fig. 23. Chicken Island, La., site 11

Test Procedures and Data Collected

Trafficability tests 28. VCI determination. Self-propelled tests were conducted to de termine the required minimum soil strength for the vehicles to complete one (VCI ) and 50 passes (VCI ) passes. In these tests each vehicle opera 1 50 ted in its lowest gear at a track speed of approximately 2 mph, tracking back and forth in 100-ft-long, straight-line test lanes until it became immobilized or completed 50 passes. (Any deviation from this procedure is noted in the remarks column of the data tables herein.) 29. Before traffic began, a 100-ft-long test lane was staked out and cone index of the soil was measured at the surface and at 3-in. vertical increments to a depth of 18 in. and at 24-, 30-, and 36-in.

24 depths. These measurements usually were made at 10-ft horizontal inter vals along the expected paths of both tracks of the vehicle. Remolding indexes were measured (at the stations where the lowest cone index was recorded) for 0- to 6-in., 6- to 12-in., and 12- to 18-in. depths. At the remolding index stations, surface shear measurements were made with the sheargraph vane and rubber shear heads. However, these measurements could not be made for some tests because of surface water or extremely soft soil conditions on which shear strength measurements could not be made at more than one normal load. Moisture content and density samples were taken from the surface to a depth of 18 in. at each remolding station. Field and laboratory techniques were used to identify soil type to a depth of 18 in. Vegetation was described in terms of height and estimate of percentage of ground cover. During traffic, cone indexes (at the same horizontal and vertical intervals as before-traffic measurements) and rut depths were measured. Observations of the soil and vehicle behavior were recorded during each test. 30. Drawbar pull tests. In each towing test, measurements of drawbar pull and slip were made by attaching a load cell to a 70-ft-long cable extending from the rear of the test vehicle to the front of the load vehicle. The test vehicle (operated in its lowest gear) pulled the load vehicle at a steady engine speed of 2500 rpm (approximately 2 mph), and the load-vehicle driver increased the load in several stages (by applying brakes gradually) from no load-no slip to high load-high slip or stall out. At all times the test-vehicle driver maintained a steady engine speed. To determine slip, the distance the vehicle traveled was measured by a string payout line, and the distance the traction com ponent traveled was obtained by recording a portion of a revolution of the drive sprocket. A continuous record of drawbar pull and a record of distance the test vehicle and track traveled were obtained simultaneously. As the records were being made, they were observed by the test engineer for any irregularities. Measurements were made in this manner until a sufficient number of load and slip combinations were recorded to develop a drawbar pull-slip curve. Each test was repeated to ensure that the maximum drawbar pull had been attained; all test measurements were used

25 in determining the average maximum drawbar pull. 31. When a conventional vehicle moves forward at no slip, the dis tance that a point on the periphery of its track (or wheel) moves in space is equal to the distance that the vehicle moves along the ground. Percent slip was computed according to the following equation

distance traveled by track or wheel - distance traveled by vehicle % slip = 100 X --~~--""7'"""---::---::-~----:----:----:----::---- distance traveled by track or wheel

The distance traveled by a conventional vehicle cannot be greater than that traveled by a point on the track or wheel (unless the vehicle is sliding downhill or in the process of being towed), and thus slip cannot be nega tive. The XM759, however, actually moves twice the distance that the track chain moves in the same period when it is operating with rolling wheel track action, and in this case, slip according to the equation above is -100%. When the XM759 first begins to operate with stationary-wheel track action, it moves the same distance as the track chain and slip is zero. All conventional vehicles are said to be undergoing 100% slip when wheels or tracks are spinning but the vehicle is making no progress. 32. Before each drawbar pull test was conducted, a flat level area of uniform soil strength that was large enough to accommodate the desired number of tests was staked. A sufficient number of cone index measure ments were made to ensure uniformity of the staked-off area. Cone index, remolding index, shear stress, and vegetation were measured, and soil samples for field and laboratory identification and moisture content and density determinations were collected in the same manner as for the vcr tests. 33. Towed tests. Towed tests were conducted in conjunction with most drawbar pull tests. With the test vehicle's transmission disengaged, the force required to tow the vehicle at a speed between 1 and 2 mph was measured. 34. Water exit tests. A few special tests were conducted with the vehicles approaching land from water deep enough to float them. stream banks occur in various configurations, and vehicle performance capability is affected by bank configuration, vehicle buoyancy, and deposition of

26 water onto the bank surface by the vehicle traction elements. Sufficient tests were run to determine limiting bank conditions. Ground profiles were obtained for all tests. Cone index measurements were made above and below the waterline. Shear stress measurements were made above the water line. Locations of the data stations along the profile varied with each profile. Moisture content, density, and bulk samples were obtained for laboratory classification from the surface to a depth of 18 in. for most tests. Field classification of soil was made for all tests. Observations of vehicle performance were recorded for all tests. 35. Maneuver tests. Where feasible, one-pass maneuver tests were run on courses staked out in a single terrain type and adjacent to the mobility test course. The test course pattern (as shown below) required the vehicle to execute two left turns (A and D) and two right turns (B and C). The turning points at A and D were laid out at known station numbers assigned to the mobility test course. Usually the distance be-

B .... 100 FT C

l- LL MANEUVER COURSE 0 ~ t MOBILITY TEST COURSE A 0

STA STA NO. NO. tween control stakes was 100 ft. The Ml16 traversed the course on one side of the control stakes, and the XM759 traversed the course on the other side. The test-vehicle driver negotiated each turn in low trans mission range as tightly and as qUickly as the vehicle and terrain would allow. After the initial pass of both vehicles, cone indexes were meas ured at each control stake in the undisturbed area adjacent to the paths taken by the vehicle. Rut depth and turning radius data were also col lected at each turn. Time (in seconds) needed for the test vehicle to make each turn and pertinent notes of vehicle performance were recorded. Mobility tests 36. At each test site at least one straight-line test course was

27 laid out to include a number of different terrain types. The test course and points of change in terrain type were clearly marked with stakes and flags to help determine incremental speed and to assist the vehicle driver in maintaining the desired position on the test course. The XM759 tra versed the course on one side of the stakes and the Ml16 on the other. The test courses were positioned to ensure that the test vehicle entered each terrain type at right angles. After the test course had been laid out and the data collected had been examined, the driver (or drivers) was given specific instructions as to the course layout, the significance of markers on the test courses, and the gear or gears in which the vehicle should achieve the maximum speed for the terrain conditions that would be encountered. He was also instructed to maintain a maximum speed that, in his jUdgment, would not endanger his safety or damage the cargo or vehicle. The time required for a vehicle to cross each individual terrain type (from the time the front of the vehicle entered until the time the rear of the vehicle left the terrain type) and the total elapsed time for the vehicle to traverse the test course were measured by a stopwatch and recorded for each test. The test vehicles with a 100% pay load tra versed each test course in one direction and then turned around and made the second run in the opposite direction, following the same path as the first run. This pattern usually was followed until four successive runs were made with each vehicle. Next, this same pattern was followed with each vehicle empty and operating in the same ruts as the loaded vehicle. 37. Sufficient data were taken to describe each terrain type ade quately. Cone index measurements were made along the center line of each test within each terrain type. Because the distances across terrain types varied, cone indexes were measured at various horizontal intervals. Remolding index and surface shear strength (sheargraph) measurements were made, and soil samples for moisture content and density determinations and for field and laboratory identification of soil type were collected at arbitrary locations within most terrain types in the same manner as for the vcr tests. Vegetation data were collected in terms of kind of vegetation, height, root depth, and percentage of ground cover for each terrain type (where feasible, stem diameter and stem spacing were

28 measured). After the initial run of both vehicles, rut depth was meas ured along the test course. Pertinent observations of vehicle performance on each run were recorded.

29 PART IV: ANALYSIS OF DATA

38. The analysis of data for the trafficability tests consisted of the development of terrain-vehicle relations normally considered as conventional measures of off-road vehicle performance. For the mobility tests, the average speed at which the test vehicles negotiated each ter rain type and the length of the mobility test courses were considered in the data analysis.

Trafficability Tests

39. The relations developed include: (a) RCI versus number of passes completed, from which VCIl and VCI determinations were made, 50 (b) drawbar pull versus slip, (c) RCI versus maximum drawbar pull, (d) RCI versus motion resistance, and (e) RCI versus turning radius. In establishing these soil strength relations, the 3- to 9-in. layer was considered the critical layer for both test vehicles, and for 1- and 50 pass traffic. RCI was used as a measure of soil strength for the tests conducted on fine-grained soils and organic soils that contained suffi cient decomposed organic matter for which a remolding index could be ob tained, using procedures established for fine-grained soils. CI of the critical layer was used as a measure of soil strength for tests on or ganic soils that contained predominantly peaty material.

Experimental VCI deter mination for fine-grained soils 40. Twenty VCI tests were conducted with the XM759 and Ml16 on consolidated organic, organic-clay, and clay soils to determine VCIl and VCI . Table 3 is a summary of soil data and test results. 50 41. XM759. Seven tests were conducted to determine VCI at two dif ferent pay loads: four tests (6, 9, 17, and 19) at 100% rated pay load and three tests (11, 13, and 15) at 200% rated pay load (see fig. 24). The RCI for the 3- to 9-in. depth is plotted against the number of passes com pleted for the 100% and 200% pay-load tests in plate 8. Notice that for

30 Fig. 24. VCI test lanes 14, 15, 16, and 17, after traffic

both pay loads, the XM759 was able to complete 50 passes on soils whose strength was as low as 2 RCI. Although the XM759 did not become im mobilized on the soil conditions tested, test notes and observations show that there was a difference in performance in terms of speed and ease with which the vehicle negotiated each pass. For those tests conducted on soils with an RCI of 7 or less with 100% pay load (tests 6, 9, and 19) and 200% pay load (tests 11 and 13), vehicle speed was reduced to less than 1 mph after about 20 passes, and track slippage was high. In tests on soils with an RCI greater than 7 with 100% pay load (test 17) and 200% pay load (test 15), the vehicle completed 50 passes with little or no track slip, and a speed of about 2 mph was maintained during each pass. Results of these tests indicate that the minimum soil strength that will permit easy 50-pass "go" performance of the XM759 for the pay loads tested should be about 7. Apparently, one pass can be made with relative ease over soils of any strength.

31 42. IYfi16. Six tests were conducted with the IYfi16 without a pay load in establishing an RCI versus number-of-passes-completed relation. In five of the tests (2, 10, 12, 14, and 23) the IYfi16 became immobilized before 50 passes were completed. In one test (8) the vehicle completed 50 passes, but with difficulty. A plot of 3- to 9-in. layer RCI and number of passes completed for these tests and a curve of best visual fit separating "goll from llno goll tests are shown in plate 8c. This plot shows that the experimental VCI50 is 12 and VCIl is 6 for the Ml16 without pay load. 43. Seven tests were conducted with the Ml16 at 100% rated pay load. In addition, data for six tests of this vehicle with a 100% rated pay load, conducted in 1964 near Vicksburg, Miss., on a CH soil were in cluded in the analysis. A plot of 3- to 9-in. layer RCI and number of passes completed and a curve of best visual fit separating llgoll from llno go" tests are shown in plate 8d. Of the seven tests conducted for this program the vehicle became immobilized in four (1, 5, 7, and 16) and completed 50 passes without difficulty in three (3, 4, and 18). All tests conducted in 1964 resulted in immobilizations before 50 passes could be completed. Plate 8d shows that the experimental VCI50 is 14 and VCIl is 7 for the Ml16 with a 100% pay load.

Experimental VCI deter mination for organic soils 44. Only three tests (20, 21, and 22) were performed on soils with sufficient peaty material to be classified as organic soils. All three tests were conducted in areas of unconsolidated organic soil. The range of strengths tested was not sufficient to establish minimum soil strength requirements for organic soils. The results of these tests are discussed in the following paragraphs and a summary of soil data and test results is shown in table 3. 45. XM759. Tests 21 and 20 were conducted with zero and 100% pay loads, respectively. Test 21 was run on a before-traffic CI of 9. The test was terminated after 30 passes because the soil was reduced to a fluid condition, and it was apparent that the XM759 could complete

32 50 passes. Test 20 was run on a befo~e-traffic CI of 8, and after 15 passes, the CI was reduced to zero; the vehicle completed 15 passes with ease. After traffic was completed, the vehicle had difficulty in exiting the test lane because of the step heights formed at both ends of the lane. In test 21, the vehicle was able to exit the lane after several attempts, but in test 20, the vehicle required assistance before it could leave the lane. 46. Ml16. Test 22 was conducted at 100% pay load on a before traffic CI of 5. The Ml16 broke through the floating organic layer and was immobilized on the first pass.

Comparison of computed and experimentally determined VCI's 47. The VCI was determined using equations developed by WES for 50 fine-grained and organic soils for both the XM759 and the Ml16 for the gross weights tested. The equations used and the computations made to solve these equations are given in Appendix A. 48. The computed and experimentally determined VCII and VCI for 50 fine-grained soils are as follows: VCI VCII Pay Load 50 Vehicle % Computed Experimental Computed Experimental XM759 100 18 7 7 >2 200 21 7 8 >2 Ml16 Empty 25 12 10 6 100 29 14 12 7

It can be seen that the computed VCI 's are very conservative. The 50 VCI for the XM759 is more conservative than that for the Ml16 because 50 certain assumptions were required in the VCI determination. The com puted VCI for all tracked vehicles weighing less than about 10,000 Ib 50 and with ground contact pressures less than about 1.5 psi is very con servative. The reason for this is that in the vehicle tests conducted for the development of the VCI computation technique,* only one

* u. S. Army Engineer Waterways Experiment Station, CE, "Trafficability of Soils; Vehicle Classification," Technical Memorandum No. 3-240, Ninth Supplement, May 1951, Vicksburg, Miss.

33 low-ground-contact-pressure vehicle (M29C weasel) was used, and its tracks jammed because of mud buildup when operating in soft, fine-grained soils. In certain low-plasticity soils, the M29C completed 50 passes on an RCI of 13, but considerable mud buildup occurred, leading to immobilization in highly plastic soils at this RCI. Thus, as a conservative measure, 25 waS assigned as the vehicle's VCI . If this vehicle's configuration were 50 not conducive to immobilization by track jamming, a VCI of about one 50 half the computed VCI could have been used. SO 49. The pneumatic tires and sponson of the XM759 provide immediate buoyancy when immersed in soft, viscous soils, thus reducing the effective weight (gross vehicle weight minus buoyancy) of the vehicle by an amount equal to volume displaced times the unit weight of the viscous soil. Since the buoyancy of soft soils affects the weight of the vehicle, which in turn directly affects VCI determinations, a closer agreement was sought between computed and experimentally determined VCI by considering the 50 effects of soft soil buoyancy. The results of this consideration are given in Appendix B. Curves were drawn representing lines of equal buoy ancy for different combinations of wet density and vehicle sinkage (see ulate B2). For example, at 24-in. sinkage and 85 pcf wet density, the. XM759 vehicle weight is decreased by about 6545 lb, and at 30-in. sinkage in the same soil,the vehicle weight is reduced by about 9600 lb. In several tests, deep sinkages were encountered after 20 to 50 passes (tests 9, 13, and 19). As shown in paragraph 8, Appendix B, the effective weight was 3510 lb for test 9, 1240 lb for test 19, and 2630 lb for test 13. By taking into account the lowering of effective weight through buoyancy, com puted VCI's can be obtained that more nearly agree with experimental VCI's. Reduction of effective weight may explain why the XM759 completed 50 passes (with difficulty) on an RCI of 2 (paragraph ~l), since a com putation would show that when effective weight (Appendix B) is less than 5700 lb, VCI becomes zero. Drawbar pull tests 50. Forty drawbar pull-slip tests were conducted at sites 7 and 8 in organic clay (CR-OR) and lean and heavy clay (CL and CR) soils. Tests were run in two areas at site 7 and seven areas at site 8. Soil strength and terrain data for each area are summarized in table 4, and drawbar pull-slip data for each test are summarized in table 5. The number of tests conducted with each vehicle and the pay loads for each set of tests are as follows:

Vehicle Pay Load, Ib Test Weight, Ib No. of Tests XM759 0 10,000 7 3000 13,000 9 6000 16,000 9 Ml16 0 7,600 7 3000 10,600 8 Total 40

51. Drawbar pull-slip relations. These relations for the XM759 at test weights of 10,000, 13,000, and 16,000 Ib are presented graphically in plates 9, 10, and 11, respectively, and for the Ml16 at 7600 and 10,600 Ib in plates 12 and 13, respectively. In each plate, drawbar pull slip curves are shown for each test area and also as a family of curves for all areas. Test results are discussed in the following subparagraphs. a. XM759. On an RCI of 75 in area 7, the XM759 did not have sufficient power to develop 100% slip; therefore, the draw bar pull-slip values measured just prior to a halt in for ward progress are plotted as closed symbols in plates 9-11. As mentioned in paragraph 31, when the XM759 operates as a rolling-wheel track, slip ranges between -100 and 0% slip, depending on the soil conditions and drawbar pulls; when it operates as a stationary-wheel track, slip ranges between o and +100%. Plates 9-11 show that the XM759 was able to develop drawbar pull while in the rolling-wheel track mode in areas 7 and 8 only (RCI's of 45 and 75, respectively). In all other test areas, drawbar pulls were developed only when operating in the stationary-wheel track mode. In general, for those tests where the XM759 could operate only in the stationary-wheel track mode, maximum drawbar pulls increased with increase in vehicle weight. The percentage of slip at which maximum pulls were developed varied from test area to test area and with vehicle weight, but gen erally maximum pulls had been attained by the time the ve hicle slip had reached 50%. For a few tests, pulls in creased at a small rate compared to high rates of increase in slip after 50%. b. Ml16. Drawbar pull of the Ml16 increased rapidly at low slip, and for most conditions tested, maximum drawbar pull

35 was attained at slip of less than 25%. Except for tests at 7600 lb in areas 3, 4, and 8, maximum drawbar pull was maintained at high slip.

52. Maximum drawbar pull versus soil strength. The maximum draw bar pull was obtained from the drawbar pull-slip curves developed for the individual tests. Maximillll drawbar pull values were read from the curves at 50% slip unless maximum pull occurred at less slip, in which case the lesser slip value was used. Maximum drawbar pull was converted to trac.". tive coefficient (maximum drawbar pull, lb, divided by test weight, lb) and plotted against the RCI for the 3- to 9-in. layer. The relations ob tained are shown in plate 14. The maximum drawbar pull and tractive co efficient (TC) for each test used in the analysis are tabulated below, and test results are discussed in the following subparagraphs.

Draw- bar Maximum Drawbar Pull at 50% or Less Slip RCI Pull XM759 Mll6 3 to Area 10,000 lb* 13,000 lb* 16,000 lb* 7600 lb* 10,600 lb* 9 in. No. --lb --TC lb TC lb TC --lb --TC lb TC Site 7 9 1 4200 0.32 4500 0.28 4300 0.40 6 2 3300 0.25 2800 0.18 no go Site 8 23 3 2400 0.24 2500 0.19 2300 0.14 6400 0.84 7200 0.68 13 4 2300 0.23 3300 0.25 2900 0.18 6800 0.89 8000 0.75 4 5 3000 0.30 2800 0.22 2700 0.17 800 0.10 1100 0.10 12 6 3000 0.30 4200 0.32 5400 0.34 4200 0.55 4500 0.42 75 7 6400 0.64 6400 0.49 7000 0.44 6300 0.83 7800 0.74 45 8 4000 0.40 5500 0.42 5400 0.34 6700 0.88 7800 0.74 12 9 2200 0.22 2800 0.22 3400 0.21 5200 0.69 7100 0.67

* Test weights.

a. XM759. Plate 14 shows maximum TC plotted against RCI for each weight tested. The curves have the same general shape and show an increase in TC from 5 RCI up to about 10 RCI, then a decline in TC between 10 and about 25 RCI, and then an increase in TC between 25 and 75 RCI. At an RCI of 75, the vehicle approached its power limitation (insufficient power to develop sufficient force to shear the soil) resulting in maximum drawbar pulls of 6400 lb

36 for 10,000- and 13,000-lb test weights and 7000 Ib for the 16,000-lb test weight. Usually, the maximum drawbar pull of conventional tracks with aggressive grousers operating on fine-grained soils increases as RCI increases up to a given soil strength, beyond which only slight increase in drawbar pull occurs with a large increase in soil strength. The dip in the XM759 curves in plate 14 is a result of tests run in drawbar pull areas 3, 4, and 9 where the moisture content (surface- to l-in. depth) was greater than 100% and the vegetation consisted of 100% coverage of coastal Bermuda grass and marsh grass 10 to 16 in. high. The RCI was high enough to support the ve hicle with little sinkage (note the low motion resistance in these areas in table 5), and as the XM759 moved over these areas, the vegetation was compressed into a wet mat, limiting the amount of traction which the vehicle could develop (for example, see fig. 25). Consequently, the de crease in pull between about 10 and 25 RCI was due to a combination of soft surface soil and wet vegetation which resulted in low traction.

Fig. 25. Drawbar test with XM759 (100% rated pay load), area 9. (Note wet vegetation compressed into soil surface)

b. Ml16. Figs. d and e of plate 14 show maximum TC versus RCI for two test weights. For the 10,600-lb test weight, data from the 1964 tests were included (see paragraph 43). The curves show that TC increases rapidly from the minimum

37 soil strength to about 15 RCI points above the minimum, beyond which little or no change occurs in TC with an increase in soil strength. At test weights of 7600 and 10,600 lb, the maximum TC's were 0.89 (6800 lb) and 0.75 (8000 lb), respectively. The Ml16 with 100% pay load approached its power limitations at an RCI of about 75. Vegetation in areas 3, 4, and 9 did not affect drawbar pull with this vehicle as it did with the XM759.

Towed tests 53. The motion resistance of each vehicle was measured following each drawbar pull test. The test vehicle with the engine stopped and transmission disengaged was pulled backward at approximately 2 mph in a lane adjacent to the drawbar pull-slip test lane. Motion resistance in pounds and resistance coefficient (motion resistance, lb, divided by vehicle weight, lb) for each vehicle and each test weight used in the analysis are tabulated below: Drawbar Motion Resistance Pull XM759 Ml16 Area 10,000 lb 13,000 lb 16,000 lb 7600 lb 10,600 lb No. lb RC lb RC lb RC lb RC lb RC ------Site 7

1 1600 0.12 2900 0.18 2300 0.22 2 1700 0.16

Site 8 3 700 0.07 1000 0.08 1100 0.07 1300 0.17 4 800 0.08 1200 0.09 1100 0.07 1300 0.17 1600 0.15 5 2200 0.22 2500 0.19 3800 0.24 2400 0.32 3100 0.34 6 1500 0.15 2000 0.15 2400 0.15 1800 0.24 2200 0.21 7 700 0.07 900 0.07 1000 0.06 1100 0.14 8 800 0.08 900 0.07 1200 0.08 1100 0.14 1450 0.14 9 1000 0.10 1200 0.09 1400 0.09 1200 0.16 1500 0.14 The motion resistance coefficient (RC) is plotted against the 3- to 9-in. RCI in plate 15. Since the RC's for the XM759 and Ml16 are similar for all test weights, the vehicle data plots include all test weights. 54. XM759. The motion resistance data, in terms of RC, are plotted against corresponding RCI data for the 3- to 9-in. layer in plate 15a. A curve of best visual fit is drawn through the data points. The force required to tow the XM759 varied from 24% of the vehicle weight on an RCI of 2 to about 8% of the vehicle weight on an RCI of 20. Beyond an RCI of 20 little or no change occurred in towed force required. 55. Ml16. A similar motion resistance-soil strength relation was established for the Ml16, and it is shown in plate 15b. The towed force was affected by soil strength in the 4- to 30-RCI range. At 4 RCI the force required to tow the vehicle was 34% of the vehicle weight, and at 30 RCI the towing force was 14% of the vehicle weight. Maneuver tests 56. Maneuver tests were conducted in courses adjoining 10 mobility test courses and having a range of soil strengths and a variety of vegetal cover. Eleven maneuver tests were run on the Virginia test sites and eight were run on the Louisiana test sites with the XM759 and Ml16 at 100% rated pay load. The test sites used and the number of tests con ducted at these sites are given in the following tabulation. The data collected for these tests are summarized in table 6.

Site No. of Tests No. Ml16 Total Virginia Test Sites 1 1 o 1 2 2 1 3 3 2 o 2 4 2 1 3 5 1 1 2 Total 8 3 II Louisiana Test Sites 6 1 1 2 7 1 1 2 8 1 1 2 10 1 o 1 11 1 o 1 Total 5 3 8

57. The analysis of the maneuver test data consisted of relating the turning radius expressed as the radius of the circular path of the test vehicle's outside track and vehicle speed in executing 90-deg turns to the ReI of the 3- to 9-in. layer. The data plots of soil strength and speed showed only a general trend of speed increasing with the increase in

39 soil strength. Therefore, a plot of these data is not shown. Plots of turning radius versus soil strength for the XM759 and Ml16 are shown in plate 16. The turning radius on pavement for the XM759 was available and is included in the data plot. In some of the tests the vehicle skidded sideways while executing a turn. 8kidding usually was caused by centrifu gal force on wet surfaces that provided low traction. The data show that the correlation between turning radius and soil strength is poor. For ex ample, on an ReI of 4, the turning radius for the XM759 ranged from about 20 to 148 ft. (The XM759El program now underway wherein an infinitely vari able ratio transmission-steer unit will be installed should improve turning capabilities in soft soils.) The scatter in data, however, is much less at the higher soil strengths. The curves on the data plots are drawn to indi cate the maximum turning radius that could be expected for a particular soil strength. The poor correlation obtained can be partly attributed to the test procedures wherein speed was an inherent uncontrolled variable, since the vehicle driver was instructed to negotiate each turn as tightly as pos sible while in low transmission range but not necessarily in low gear. As a result, speed varied within and between tests. Relations for this type of test could be improved by maintaining a constant speed throughout each test. Water-exit tests 58. The water-exit tests were run on a range of step heights to determine the maximum step height that the test vehicles could negotiate. An attempt was made to establish limiting conditions for bank slope and soil strength that would produce immobilization. However, the desired range of combinations of bank slope and soil strength were not found in the wet marsh terrains tested. In most instances, soft soil was asso ciated with shallow banks. The XM759 was able to negotiate these banks, but the Ml16 usually became immobilized. The soft soil-slope immobiliza tions are discussed sUbsequently under mobility tests (paragraph 67). The analysis is restricted to the effects of step height only. 59. Ten water-exit tests, five with the XM759 and five with the Ml16, at 100% rated payload were conducted at Bayou du Large, La. (fig. 26). A summary of soil data taken on the bank and underwater is given in table 7. Ground and water profiles for each test are shown in plate 17, and

40 Test 3 Test 4

Test 7 Test 8

Fig. 26. Water-exit tests, Bayou du Large, La., site 8 photographs of the vehicles exiting water bodies are shown in fig. 26. On each profile (plate 17) the vehicle is positioned in relation to the prog ress it made in negotiating the bank. Where the vehicle is shown to the left of the bank, the indication is that the vehicle negotiated the bank. In all tests the soil on the banks was generally a firm clay that did not deform significantly under traffic. 60. The test results are summarized below:

XM759 (13,000 Ib) Ml16 (10,600 Ib) Test No. 1 4 5 2 3 7 8 2 6 3 Step height, ft 3.4 2.6 2.9 2.5 2.2 4.0 2.8 2.5 2.6 2.2

X X X X X No go x x X X x

In all tests the XM759 was able to project its front end over the lip of the top bank; however, due to the loss of traction between tire and soil, the vehicle could not negotiate steps higher than about 2.2 ft (test 3). Traction losses were the result of the wet-smooth tires and wet-firm soil banks that were wetted by wave and splash action generated by the vehicle as it approached the bank. The Ml16 was able to climb a 2.8-ft step height (test 8) because the track grousers were effective in overcoming the slippery bank conditions caused by wave and splash action generated by the vehicle.

Mobility Tests

61. Mobility tests were conducted at all test sites on 15 test courses. Detailed soil and terrain data for each test course are shown in tables 8 and 9, respectively. Profiles of the test courses, including ground surface, vegetation height, surface water level, and ground photo graphs are shown in plates 1-7. Analysis of data was made on the basis of vehicle speed over terrain types and test courses. Speed was deter mined as the average run speed for the first and second runs when each vehicle was loaded to 100% pay load (13,000 Ib for the XM759 and 10,600 Ib for the Ml16). The same driver was used for nearly all first and second runs (exceptions were runs at test site 1 and run 2 at test site 2).

42 Speeds on various types of terrain 62. In the mobility tests, 47 terrain types were tested. The speeds recorded for the XM759 and Ml16 on the individual terrain types tested at each mobility test course are given in table 10, and the average speed for each vehicle on each terrain type tested is given in table 11. The average speed that each vehicle could achieve in the ter rain types tested on the first run according to an arbitrary speed class is given below. No. of Terrain Types in Which Vehicle Achieved Speed Class on First Run Speed Class XM759 Ml16 o (immobilization) 1 9 0.1-1.0 o 0 1.1-2.0 o 0 2.1-3.0 6 1 3.1-4.0 7 5 4.1-5.0 7 2 5.1-6.0 7 5 6.1-7.0 5 5 7.1-8.0 5 2 8.1-9.0 2 4 9.1-10.0 6 0 10.1-11.0 1 1 11.1-12.0 o 1 47 35* * Mll6 was not able to reach 12 of the terrain types tested with the XM759.

63. XM759. From the tabulation above it can be seen that the XM759 had a zero speed in one terrain type and a speed between 10.1 and 11.0 mph in one terrain type. The number of terrain types that the XM759 could negotiate in speed classes between 2.1 and 10.0 mph ranged from 2 to 7. 64. An examination of table 11 shows that in the first run the XM759 attained a maximum speed of 10.23 mph in terrain type 30 and zero speed (immobilization) in terrain type 46. The minimum speed other than zero was 2.08 mph in terrain type 4. The only innnobilization occurred in terrain type 46 at site 1 at station 2+45 while the vehicle was exiting a tidal flat and attempting to negotiate the edge of a terrace formed at the high water boundary. The 3- to 9-in. ReI was 2 in the tidal flat and 8 in the terrace. When the XM759 approached the edge of the terrace, the dis tance between the bottom of the track, with about 3 ft of sinkage, and the top of the terrace was 44 in. Although the vehicle was unable to surmount the step height encountered, it had no difficulty backing out into the tidal mud fJ,.at. 65. A comparison of the vehicle speeds (table 11) for the first and second runs shows that there is no consistent pattern. It was anticipated that the second-run speed would be greater since the driver would be famil iar with the test course, but the data do not bear this out. In 18 of the 47 terrain types tested, the second-run speeds were lower than the first run speeds. The small differences in speeds run in terrain types in which obscuration by vegetation was not significant can probably be attributed to driver inconsistencies and slight changes in test course conditions between the first and second runs resulting in higher track slip. For those terrain types in which the second-run speed was greater than the first-run speed by approximately 2 mph, vegetation affected driver visi bility significantly on the first run. 66. Mll6. As shown in paragraph 62, the Ml16 was tested in only 35 terrain types because it could not reach 12 of the terrain types in which the XM759 was tested. For the terrain types tested, the Ml16 had a zero speed in nine terrain types and a speed between 10.1 and 12.0 mph in two terrain types. Between 2.1 and 9.0 mph, the number of terrain types within each speed class ranged from 1 to 5. 67. Table 11 shows that for the 26 terrain types traversed the maximum first-run speed of the Ml16 was 11.25 mph in terrain type 7 and the minimum first-run speed was 2.22 mph in terrain type 20. The Ml16 was unable to negotiate terrain types 1, 2, 23, 28, 34, 36, 37, 39, and 40. Except for terrain type 40, the immobilizations were caused by the soil strength being less than the required VeIl. In terrain type 40, at site 7, stations 10+13 to 10+45, the Ml16 immobilized when it nosed into the bank of the drainageway at station 10+45. The vehicle was able to back up without assistance. 68. XM759 and Ml16 second runs. The XM759 was immobilized on the

44 first run on one terrain type but not immobilized on any second runs attempted; the Ml16 was immobilized on the first run on nine terrain types and on one terrain type on the second run attempted. Special considera tions for determining speeds were made in certain instances, as follows. When a vehicle was immobilized during the first run on a mobility test course, the test was usually terminated. At site 4 all the second-run tests were made at speeds that produced extremely rough rides; therefore, the data were not used in averaging terrain type speeds (terrain types 5, 9, 12, 13, and 25). For terrain type 27, the second-run speed is shown as zero because the vehicle immobilized as a result of limiting soil condition (ReI of 6); the high speed on the first run was a result of momentum developed on the preceding terrain type. The reason for dif ferences in first- and second-run speeds are the same as those discussed in paragraph 65. Speeds on mobility test courses 69. The average speeds of the test vehicles on 15 mobility test courses for the first and second runs are tabulated below. Figs. 27 and 28 show the vehicles in operation on one test course.

Fig. 27. XM759 operating on site 3, course 2, between sta 3+04 and 3+29 Fig. 28. Ml16 immobilized on site 3, course 2, between sta 0+00 and 1+20

Mobility Test Course Speed, mph. XM759 Ml16 (1000/0 Rated (100% Rated Site Course Pay Load) Pay Load) No. No. --Run 1 Run 2 Run 1 --Run 2 1 1 0 0 2 1 3.86 4.68 3 1 2.95 3.05 0 2 2.61 2.46 0 4 1 3.35 3.85 0 5 1 11.18 10.62 12 .18 10.66 6 1 7.63 8.62 0 0 6A 2 2.69 6.26 2.86 7.58 7 1 9.54 11.69 0 2 6.94 8.52 0 8 1 7.31 6.24 0 9 1 6.96 5.74 0 10 1 6.64 6.39 0 lOA 2 2.56 11 1 5.47 4.02 0

46 70. XM759. The XM759 completed all test courses, except the course at site 1 where it immobilized (paragraph 64). The maximum first-run speed was 11.18 mph at site 5, course 1, and tbe minimum was 2.56 mph at site lOA, course 2. The maximum second-run speed was 11.69 mph at site 7, course 1, and the minimum was 2.46 mph at site 3, course 2. The reason for the differences in first- and second-run speeds is discussed in paragraph 65. 71. Ml16. Because of the presence at some place in the test course of soil of a strength below the minimum required for one pass, the Ml16 was able to traverse only two of the mobility test courses- course 1 at site 5 and course 2 at site 6A. The speed at which the Ml16 negotiated these test courses was greater than the speed at which the XM759 could negotiate them.

Notes and Observations

72. Pertinent information not presented in the data analysis is discussed in the following paragraphs.

Vegetation and soil build up in track system of XM759 73. At site 2, vegetation and soil buildup had to be cleared from the XM759 track system a number of times to prevent track fouling. This buildup was especially noticed where ReI was less than about 6. On one occasion after the vehicle had moved approximately 5000 ft, sufficient vegetation and soil had accumulated between the tires and cargo bed and along the top of the sponson to force the drive chain away from the sprockets causing the sprocket axles to twist out of alignment (see fig. 29). 74. Later, the left sponson was modified and the vehicle was again tested at site 2 to compare the buildup between the modified left sponson and the unmodified right sponson. For this test the continuous level platform at the top of the left sponson, the platform supports, and the top wheel guide were removed; this left the wheels elevated above a surface that sloped downward and to the outside of the vehicle. After Fig. 29. Vegetation and soil accumulation on sponson of XM759 (upper outside triangular panel removed) approximately 5 miles, the accumulation on the modified left sponson was slightly less than that on the right. It also was obvious that vegetation and soil accumulation was slower than it had been in the previous test. During this test an abnormally high tide placed 2 ft of water over the site; this amount of water had not been present during the preceding test. The added water was instrumental in creating a washing action that de creased the rate of buildup in the vehicle's track system. On the basis of observation, it is obvious that for detrimental vegetation buildup, heavy damp vegetation must be associated with very soft soil which permits the XM759 to sink to a depth where the chain at the bottom of the track will be at or below the surface. In this condition, the vegetation stems or roots become entangled in the chain, which in turn carries and deposits the vegetation clumps on top of the sponson. The maximum vegetation buildup occurred in the organic marshes tested in Virginia. Similar marsh conditions are not known to occur in Southeast Asia; however, Southeast Asian wet-season marshes and floating rice near harvest season may produce adverse vegetation buildup.

48 other XM759 immobilization 75. The XM759 immobilized once while operating at site 8, Bayou du Large. This immobilization occurred when the vehicle was operating with a 200% pay load and returning to the staging area at the edge of Bayou du Large. The vehicle was attempting to cross a 30-ft-wide pothole in which the RCI was about 3 and the sides of the banks were about 14 in. high. When the vehicle entered the pothole, it sank to the float level and could not negotiate the banks in either forward or reverse. The soil surrounding the pothole had a CI of 23 in the 0- to 6-in. layer. PART V: EVALUATION OF PERFORMANCE OF VEHICLES

76. The performance evaluation of the :xM759 and Ml16 is made on the basis of the trafficability and mobility test results discussed in Part IV. For the trafficability tests, similar relations developed for each vehicle are compared and discussed according to the applicability of the relation in evaluating vehicle performance in meaningful terms. The evaluation of mobility tests includes a comparison of the speed performance on indi vidual terrain types and mobility test courses.

Comparison of Trafficability Te&t Results

VCI 77. The results of tests to determine the minimum soil strength that would permit the :xM759 to complete one (VCI ) and 50 (VCI ) passes 1 50 on level soil in a straight-line path have shown that soil strength had no effect on the "go-no go" performance of the :xM759 at 100% and 200% pay loads; therefore, zero was assigned for VCIl and VCI~O' The VCIl as signed to the Ml16 was 6 for the empty vehicle and 7 for the 100% rated pay load, and the VCI assigned was 12 for the empty vehicle and 14 for 50 the 100% pay load. 78. The effects of VCIl and VCI on the ability of the XM759 and 50 Ml16 to traverse level, soft soil areas were determined on the basis of three sources of information that permitted a determination of the per cent~e of areas of soil trafficable. The three sources of information were (a) frequency distribution of RCI for humid-temperate and humid tropical climates, (b) areal distribution of soil strength in Thailand under wettest conditions, and (c) areal distribution of soil strength in six areas in the Mekong Delta. 79. Freguency distribution of RCI. Curves showing the cumulative frequency of RCI for fine-grained soils in temperate and tropical climates are presented in plate 18. Soil strength data for the 6- to 12-in. layer are shown; however, for this comparison it was assumed that the soil strength for the 3- to 9-in. layer (critical layer for the vehicles being

50 compared) was similar. Data used in the development of the temperate climate RCI frequency curve were obtained from hundreds of WES soil tests in the United States, generally east of the Mississippi River. Hundreds of RCI data from WES tests in Puerto Rico, Panama, Hawaii, Costa Rica, and Thailand were used in the development of the RCI frequency curves for tropical climates. For each climate, wet-season condition and high moisture condition are considered and separate curves are presented. The wet-season condition represents the average condition prevailing in soils during the wet season. The high-moisture condition considers the highest moisture level attained by soils during the wet season. The curves in plate 18 can only be used for soil strengths of 10 RCI and greater. Since VCI for the Ml16 at 100% rated pay load is greater than 10 (VCI 14), 50 50 an estimate of the percentages of areas trafficable at 100% rated pay load is made on that basis. The following tabulation presents the results of the comparison in a temperate or tropical climate 1lllder wet-season or high moisture conditions.

Percent of Areas Trafficable Temperate Climate Tropical Climate VCI Vehicle 50 Wet Season High Moisture Wet Season High Moisture XM759 o 100 100 100 100 Ml16 14 100 98 97 96

The tabulation shows that 100% of the areas in temperate and tropical cli mates are trafficable to the XM759 on a "go-no go" 50-pass basis. In temperate climates the Ml16 can traverse 100% of the areas in the wet sea son and 9E!P/o of the areas during high-moisture conditions. In tropical climates the Ml16 can traverse 97% of the areas in the wet season and 96% of the areas during high-moisture conditions. 80. Although the difference in areas trafficable is small on a soil strength frequency distribution basis, the area occupied in a given terrain and its occurrence in relation to other soil strength is equally important. Soft soil with an RCI of 10 or less usually occurs in narrow bands as tidal mud flats along coasts of y01lllg deltas and along the banks of delta streams and rivers. Inland, soft soils occur in poorly drained depres sions in Vlhich marshes and swamps are f01llld. Undoubtedly a study

51 restricted to deltas such as the Mekong and Mississippi Deltas would re veal a high percentage of areas with low soil strengths. It is also obvious that to increase the probability of mission success, the vehicle selected should be capable of traversing the worst soil condition along its traverse. 81. Areal distribution of soil strength in Thailand. A map (scale 1:2,500,000) showing the distribution of soil strength in Thailand under the wettest conditions is presented in plate 19. To permit a direct com parison of vehicle performance in terms of VCIl and VCI with the soil 50 strength categories mapped, it was assumed that 70% of the category less than 10 RCI contained soils with an RCI of 7 or less. For the category 10-25 RCI, it was assumed that an RCI of 10-14 represented 27% of that category. Hundreds of RCI measurements were used in preparing the soil strength map. These data, among others, were obtained during recent studies conducted by WES. other data sources on Thailand soils were also used. 82. A tabulation of the area occupied by each strength category shown in plate 19 gave the following results:

Strength Category Areal Symbol RCI Distribution, % 1 <1.0 1 2 10-25 16 3 26-60 7 4 61-160 17 5 161-400 30 6 >400 29

Total 100

83. A comparison of the percentage of area trafficable for each soil strength category with categories 1 and 2 adjusted as described in paragraph 81 is given in the following tabulation. The results show that the XM759 can traverse 100% of the Thailand soils making one or up to 50 passes without immobilizing. The Ml16 can complete one pass on 99.3% of

52 the Thailand soils and it can complete up to 50 passes on 95% of the Thailand soils.

Percent of Area Trafficable Strength Category VCI Vehicle VCIl 50 Pass 1 2 .3. 4 ..L. 6 Total XM759 1 1 16 7 17 30 29 100 ° ° 50 1 16 7 17 30 29 100 Ml16 7 14 1 0.3 16 7 17 30 29 99~3 50 ° 12 7 17 30 29 95 84. Areal distribution of soil strength in selected areas of the Mekong Delta. A map showing six areas in the Mekong Delta selected for a terrain type study is given in fig. Cl of Appendix C. This map was pre pared without the benefit of any ground data. The six areas were selected since it was thought that the range of terrain variation occurring within the Mekong Delta would occur within the selected areas. Available data for analogous terrain types in Thailand and the Louisiana coastal marshes were used in assigning soil strength categories. In this study, soil strength for the 6- to 12-in. layer was mapped using the following cate gories. The areal distribution of these categories is shown in the tab ulation below and in plate 20.

Areal Distribution Soil Category CI RCI Sq miles Percent 1 0-15 0-7 1650 11 2 16-25 8-14 4350 29 3 26-60 15-40 5400 36 4 61-100 41-70 2550 17 5 >100 >70 1050 7 In order to use the available information several adjustments were made to reduce the information to common terms so that appropriate comparisons could be made. The soil strength in the 3- to 9-in. layer was assumed to be the same as that for the 6- to 12-in. layer. To translate the CI data into RCI, available data in similar strength categories were used to assign a remol.ding index. For the first soil category, a remolding index of 0.50 was assigned, for the second category a remolding index of 0.60

53 was assigned, and for the remaining soil categories a remolding index of 0.70 was assigned. This process resulted in the RCI values given in the tabulation above. 85. An examination of plate 20 shows that the area occupied by soil strength categories 1 and 2 in the six areas mapped (about 15,000 sq miles) ranged from about 1 to 27% and 1 to 53%, respectively. Of the total area mapped, categories 1 and 2 represent about 10 and 27%, respectively. 86. A comparison of the percentage of area trafficable for each soil strength category adjusted as discussed in paragraph 83 is given in the following tabulation.

Percent of Area Trafficable strength Category VCIl VCI Vehicle 50 Pass 1 -2 .l -4 .2- Total XM759 0 0 1 II 28 36 18 7 100 50 11 28 36 18 7 100 Ml16 7 14 1 0 28 36 18 7 89 50 0 0 36 18 7 61

From the above it can be seen that on the basis of soil strength require ments, the XM759 can complete 1 or 50 passes in 100% of the areas, whereas the Ml16 can complete 1 pass on 8CJ1o of the areas and up to 50 passes on 61% of the areas. Drawbar pull performance 87. A comparison of first-pass drawbar pull performance at 100% rated pay load was made in terms of draWbar pull-slip and drawbar pull-soil strength relations. The results of these comparisons are discussed in the following paragraphs. 88. Drawbar pull-slip relations. A summary of drawbar pull-slip curves is shown in plate 10 for the XM759 and in plate 12 for the Ml16. These curves show that while traveling in the track mode the XM759 reaches its maximum drawbar pull at a higher slip (approximately 40%) than the Ml16 (approximately 18%) indicating that the Ml16 is more efficient in devel oping maximum drawbar pull. For both vehicles and for most of the tests, the drawbar pull decreased at the higher slip ranges. 89. Drawbar pull-soil strength relations. Tractive coefficient versus soil strength curves for the XM759 and Ml16 for the empty and 100% rated pay-load tests are shown in plate 21a and b, respectively. These curves reveal that the maximum traction performance for the Ml16 is superior to that of the XM759 for the empty and 100% rated pay load with the difference being greater for the empty tests. From the minimum soil strength, the Ml16 rapidly increased its traction capability to about an RCI of 25 beyond which little or no change occurred with an increase in soil strength. Up to a soil strength of about 10 RCI, the XM759 traction in creased because the tires were immersed in the soil and were effective grousers. Between 10 and 25 RCI, traction decreased because the tires did not act as aggressive grousers and the surface soil and vegetation were usually wet, creating a somewhat slippery surface condition. Finally, as the soil strength became stronger and drier surfaces were encountered, traction increased. The highest traction attained by the XM759 was on a • reasonably firm soil on which the vehicle was operated in the wheel mode. Motion resistance 90. A comparison of the effects of soil strength on motion resist ance for the XM759 and Ml16 is shown in plate 22. The curves. show that the motion resistance coefficient for the XM759 was about 50% less than that for the Ml16 for soil strengths greater than about 20 RCI. Maneuverability 91. Curves that indicate the maxinrum turning radius that can be expected for a particular soil strength are shown in plate 23. The dif ference in turning radius performance was not considered significant on

RCI I S between 40 and 8. Below an RCI of about 8, the Ml16 could not nego tiate turns while the XM759 could negotiate turns even on an RCI of 2 but only with a great increase in turning radius. Water exiting ability 92. The comparison of the ability of the vehicles to exit from bodies of water was restricted to the effects of step height only. The maximum step height that the XM759 could negotiate was 2.2ft, and the maximum step height that the Ml16 could negotiate was 2.8 ft. Thus, the water exiting capability of the Ml16 was better than that of the XM759.

55 Comparison of Mobility Test Results

Speeds on various types of terrain 93. The vehicles were tested in terrain types common to wet marsh environments. The XM759 was tested on 47 terrain types and negotiated 46 of them; the Ml16 was tested on 35 terrain types and negotiated 26 of them. To compare the first-pass speeds of the vehicles over the terrain types, the percentage of terrain types negotiated was plotted against arbitrary speed classes. The results are shown in plate 24. It can be seen that the percentage of terrain types negotiated by the XM759 for the various speed classes was greater than the percentage of terrain types negotiated by the Ml16 for the various speed classes except in speed classes 10-11 and 11-12 mph. Speeds on mobility test courses 94. Mobility tests were conducted on 15 test courses. At 100% • rated pay load the XM759 was able to negotiate 14 of them, but the Ml16 could negotiate only two of them. The average speeds for the XM759 ranged from 2.56 to 11.18 mph, and the average speeds for the Ml16 ranged from o 86 to 12.18 mph. The average speed of the Ml16 on the two courses nego tiated was greater than the average speed of the XM759 on these two courses. On the basis of negotiating soft, wet marsh terrains, the prob ability of the XM759 completing a given traverse is nmch greater than the Ml16. PART VI: SUMMARY OF TEST RESULTS AND RECOMMENDATIONS

Summary of Test Results

95. A summary of results of the test program reported herein, is given in the following paragraphs,

Mekong Delta terrain types and analogous terrain types tested 96. Of the 44 mobility-test-course terrain types used in development of analog criterion, 16 were highly analogous to one or more terrain types identified in the Mekong Delta, 14 were analogous, 12 were moderately anal ogous, and 2 were slightly analogous (see Appendix C). 97. For the six soft-soil areas selected in the Mekong Delta, it is estimated that the XM759 with 100% pay load can traverse 100% of the areas for 50 passes, whereas the Ml16 with 100% pay load can traverse only 89% of the areas on the first pass and only 61% of the areas for 50 passes (paragraph 86), VCI determination 98. The XM759 with 100% and 200% pay loads completed one and 50 passes on a soil strength as low as 2 RCI. The Ml16 at 100% pay load com pleted one and 50 passes on soil strengths of 7 and 14, respectively. The experimental VCII at 100% pay load for the XM759 was considered to be zero. 99. The high-volume tires and sponson of the XM759 provide buoyancy when immersed in soft, viscous soils, thus reducing effective weight of the vehicle. Closer agreement between experimental and computed VCI's can be achieved by considering the effects of soft-soil buoyancy (paragraph 49 and Appendix B). Drawbar pull performance 100. The maximum drawbar pull of both vehicles at 100% pay load was limited because of insufficient power to develop sufficient force to shear the soil (paragraph 51). 101. On an RCI of about 75, the XM759 developed a maximum TC of 0.64 when empty and 0.49 with 100% pay load. On the same RCI, the Ml16

57 developed a maximum TC of 0.89 when empty and 0.75 with 100% pay load (paragraph 52). 102. On an RCI of about 7, the XM759 developed a maximum TC of 0.27 with 100% pay load. The empty Ml16 was barely able to propel itself on the same RCI (plate 14). Motion resistance 103. For all test weights, the motion resistance coefficient for the XM759 was 0.18 and 0.07 at RCI's of 4 and 75, respectively. For the same RCI's, the Ml16 developed a motion resistance coefficient of 0.34 and 0.14, respectively (plate 15). Maneuverability 104. Maneuver test results were not as definite as results of other performance tests; however, general trends indicate that the XM759 at 100% rated pay load was capable of negotiating turns of slightly less radii than the Ml16 on RCI's between 40 and 8. On RCI's less than 8, the Ml16 cannot negotiate turns; the XM759 can negotiate turns on RCI's between 8 and 2 with a great increase in turning radius for a small decrease in soil strength. Data indicate that the XM759 can negotiate tighter turns on soil strengths hptween an RCI of 12 and 40 than it can on pavement (paragraph 91). Water-exit performance 105. The XM759 at 100% rated pay load negotiated a maximum step height of 2.2 ft. The Ml16 at 100% pay load negotiated a maximum step height of 2.8 ft (paragraph 60). Mobility 106. Mobility tests were conducted with the XM759 on 47 terrain types and with the Ml16 on 35 terrain types. The XM759 negotiated 46 terrain types and the Ml16 negotiated 26 terrain types (paragraph 62). 107. For those terrain types negotiated, the first-pass speeds ranged from 10.23 mph to 2.08 mph for the XM759 and from 11.25 to 2.22 mph for the Ml16 (paragraphs 64 and 67). 108. On the 15 mobility test courses, the XM759 was able to nego tiate 14 courses and the Ml16 was able to negotiate two courses. For the mobility test courses negotiated, the first-pass speeds ranged from 11.18

58 to 2.56 mph for the XM759 and from 12.18 to 2.86 mph for the Ml16 (paragraph 69). Evaluation of comparative performance 109. An evaluation of the comparative performances of the XM759 and Ml16 in terms of the terrain-vehicle relations (trafficability tests) and average speed for the terrain types tested (mobility tests) shows that the performance of the XM759 exceeded that of the Ml16 for most of the terrain conditions tested.

Recommendations

110. Based on the results of tests conducted in this program it is recommended that: a. Further investigation be made on the effects of soil buoy ancy on· the performance of vehicles that are able to nego tiate extremely soft soil. b. studies be made of means of improving traction capability of the XM759 when operating in dense, wet grasses and on bare, wet soil slopes. c. Field data be collected in Southeast Asia on areas where the XM759 may be expected to operate. d. Consideration be given to providing higher torque output to the track system. e. In order to evaluate vehicles objectively in future pro grams, vehicle performance and terrain data be collected similar to that reported herein.

59 Table 1

XM759 Characteristics

ARMY TANK·AUTOMOTIVE COMMAND VEHICLE: CARRIER, CARGO: 1'I.z TON SOFT TIRE TRACKED XM759 TYPE: LOGISTICAL CARRIER, AMPHIBIOUS

GENERAL Weight (Combat loaded) 12,400 lbs. Crew 2 TRANSMISSION Weight (less Cargo, Crew, Stowage and Fuel) 8,700 lbs. Make Detroit Tran. Div. Model 305 MC C. 01 G. 47 in. Abv. Grnd. 89 in. From Front Sprocket Type Hydra-Matic Unit Ground Pressure 1.5lbs.(sq. in. Hydraulic Converter None Ground clearance 33 in. Gear Ratio low 4.09,1 High U 4.54: 1 Reverse Oil Capacity 16 Qts. FEDERAL STOCK NO. 2320·937·1172 Cooling System Oil to Water

RUNNING GEAR STEER SYSTEM Suspension, Type Pneumatic Track Type Geared Steer {Clutch Brake Model GS 100-3 No. 01 Wheels 34 Hub Size 6 in. Oia. x 21 in. W. Turning Radius 22 Ft. (Geared Steer) Pivot (Clutch Brake) Tires, Type Pneumatic Size 24 O. x 21 W. x 6 Steering Control Mechanical (External) Hydraulic (Internal) Gear Ratio 5.33:1 (Geared Steer) land ELECTRICAL SYSTEM NOMINAL VOlTAGE 24 V D.C. MU (Clutch Brake) Water Alternator, Amperes 60 Ord. No. 10929868 Oil Capacity 10 Qts. less Filter and lines Battery, Type Ordance 6 TN auantity 2 Cooling System Oil to Water Ignition System Battery-Igniter Oistributor No. (Modified Ord) FSN 2920-722-3681 BRAKES (INTEGRAL WITH GS 106-3) Coil (Integral w/lgniter) FSN 2920-257-1346 Type Wet, Multiple Disc Operation Mechanical Turn Signals Inland Waterway Navigation lights FINAL REOUCTION COMMUNICATIONS Type Planetary Gear Ratio 3.501:1 FT{REV.8.18 Sprocket Pitch Oiam. 3.12 in. No. 01 Teeth 14 Radio Set AN /VRC-46 Overall Useable RatIo low 106,1 High 18.6:1 Rev. 1\7.7:1 location Co-Oriver's Station FIRE EXTINGUISHER PERFORMANCE Portable 5 lb. .,.... CO, Gross Horsepower to Weight Ratio 26 hpfton Max. Tractive Effort 8200 Ibs. TW{W 70% ENGINE Max. Speed 35 MPH Max. Grade 60% Make Chevrolet Model 283-V8 Type, liquid Cooled Max. Trench 72 in. Oisplacement 283 Cu. In. Bore 3.875 In Stroke 3,000 In. Max. Vertical Wall 36 in. Governed Speed 4,600 RPM Cruising Range 180 Miles Compression Ratio 8.0:1 Free Board 36 in. Fuel Gasoline Rating 80 Octane Capacity 50 Gal. Max. Gross Horsepower 160 @ 4,600 RPM OTHER CHARACTERISTICS Max. Net Horsepower 120 @ 4,000 RPM Max. Gross Torque 255 lb. It. @ 2,400 RPM Length 245·1/8 in. Max. Net Torque 210 lb. It. @ 2,200 RPM Width 110 in. Main Cooling System liouid Height 102.1/8 in. Eng. Oil Cap. 7 ats. wfFilter Ground clearance 33 in. Oil Cooling System None Table 2

Ml16 Characteristics

CARRIER, CARGO, AMPHIBIOUS: TRACKED, M116 (T116El) -s~- TO 181·11.

82·11' REt>UCllll.E ,- TOBO 79·118 J-----; REDUCIBLE TO 63-11.

MOTI: AlL DIMENSIONS SHOWN ARE IN INCHES.

Modd Li... '"'" No. Fod..,.al.t",,/c No. Capacities: M1l6 (T1l6EI) ~6172_02 212_1l-20~7 Fuel 65 pI C.. oan. (total) 10 pI GeBeral Cooling syatem 2'7 qt CARRIER. CARGO. AMPHIBIOUS: tracked. M1l6 (TI16EI) i. Crankeue. refUi 6 Qt a Uahtweiaht. Iow~dlbouette vehicle desiped to tranBport cargo Transmission. refill 16 'It and/or penonnel.. The vehicle bJ eapable of operation with fuJl Geared steeri,ng unit 10 qt rated IoBd over animproved ...... trails. hUIy eoontry. loose sand. Engine: eno•• lee. anfrosen tundra.. 1l'luake8'. 80ft marsh. roek strewn areas, Manufacturer Chnrolet and inlalld .ate-rwaY'B onder all aeuonal eonditionB In aretit!. tem Model Military version of 281 OIl In. V-8 perate. and t.ropieal zones. Movement of the truk. propels and Type overhead valve. liquId oooIed. _line steers the vehicle aD both land and .ater. T~ low net weight Displacement 283 cu in. of the vehicle enables it to be tralUlported by e&l'IrO aireralts and Bore 1% In. parubute dropped to 08in8' foreee.. Stroke I I•. Dill'ere...... Compression ratio ... 8: 1 Maximum IrOverned .peed (full load) 4600 rpm Data plata ....u. Brake horsepower. IP'OU (max w/!ltd aeees- eorieo) KO @ 4.lIOO rpm CI...II..t1o., StaDdarcl A (OTCM 37820(C)). Torque. e ..... (..,.,. wIeld ..._rlea) 210 Ib-ft @24oo rpm TransmilJ8ion: Manufaeturer Detrolt. Transmluion Div. Model 105 MC Type hydramatle CHARACTERISTICS Brakes __ . W6. multiple dl... Number ot rana" 3 forward and reverse Crew (driver) 1 Final drive gear ratio 4.1'7:1 Pusengen 11 to IS Armament: Weight: RIFI.E. 7.62 MII.UMETER: M14 1 Curb Onehldin.. fuel. oD-equipment material. and Communitation BYstem radlo and inlerpbone driver) 7.880 Ib Payload (oarao) 3.000 Ib Cr... 10.880 Ib AMMUNITION Lena-th 188'1il in. Reduoible to 181'1il in. 7.62 MM ~------180 roo..... Widtb .. 82'1il in.

Redueible to __... ~ 80 in. Heieht 79'Iil in. PERFORMANCE Reduoible to 63'4 in. MAximum grade ability 60 percent Ground deanmee 15'iJ in. Turning radius , Pivot to Infinity Fordina: depth Ampbibioua Ground pres.ure: At eurb weight 1.9 psi MAximum vert-ide obst&ele: w/3.000 Ib payload .. 2.6 psi Vehicle can climb approx 18 In. Tread. center to eenter of truk 681f.J in. Maximum width of ditc:h: Pintle hei..ht 21 in. Vehicle ean crou apprmr 58 in. Angle of approach _ Fuel consumption: Anale of departure _ On land. 4 mpa Electrical Bystem '- 24 volt On water appros: % mpa Number of batteries (12 volt) 4 Allowable speed (recommended): On lond .... .37 mph Type of batteries ~ 2HN Fuel ()('tane r"tina <.min) 80 On water ...... 4 mph Table 3 Summary of Data and VCI Test Results

Immobili Sheargraph Av-g zation Data Average Cone Index of Remolding Index of Rating Cone Index of Moisture Content of Layers Dry Density of Layers Metal Smooth Hut Test Yes Pass Pass Cone Index La~ers Layers Layers ~ Dry Wt pcf USCS Grouser Rubber Depth Site Location and No. No. or No No. No. o _3_ 6 _9_ ~ --!L.. 18 24 0-6 3-9 6-12 12-18 ~ ~ 6-12 12-18 0-6 6-12 12-18 Class. _C_ ~ _C_ 4° in.

XM759 Amphibious Cargo Carrier, 10,000 lb (Empty)

Bayou du Large, La. 21 No o 1 10 6 6 6 6 6 6 8 9 8 9 6 6 772.9 790.9 486.0 449.4 6.6 10.8 12.6 PT Site 8 (1) (20) (8) (6) (6) (6) (6) (6) (9) (10) 10 21.2 20 35.6 30 36.8

XM759 Amphibious Cargo Carrier, 13,000 lb (100% Rated Pay Load)

Beauregard Island, La. 6 No o 14 17 18 23 25 26 20 20 19 20 16 19 22 24 0.42* 0.29* 0.37* 7 7 6 9 70.3* 100.3* 75.6* 115.6* 51.5* 46.0* CH-OH 1.8* 24* 0.2* 20* Site 7 1 10 13 22 28 14 14 18 17 14 12 15 21 21 15 1.3 10 5.2 20 6.3 30 7.0 40 7.4 50 10 23 28 16 16 20 23 28 26 22 20 22 20 20 8.1 9 No o 4 8 10 11 12 12 12 12 14 16 7 10 11 12 0.42* 0.36* 0.37* 3 4 4 4 96.5* 109.9* 129.7* 129.7* 35.1* 37.0* CH-OH 1 8 12 12 10 10 12 14 16 16 17 11 11 11 12 5.4 10 6.0 20 9.0 30 13.0 40 17.0 50 No 17.0 Bayou du Large, La. 17 o 6 18 22 20 23 30 34 42 44 57 15 20 22 29 7 10 13 10 84.3* 71.9* 56.9* 61.0* 73.2* 64.2* 64.4* CH 1.1 12 0.8 12 Site 8 1 10 14 16 22 28 40 44 47 57 66 13 17 22 37 1.5 10 5.4 20 6.1 30 9.2 40 11.2 50 8 10 16 28 36 40 52 60 67 76 11 27 43 12.3 No 17 19 o 2 5 6 5 6 6 10 14 26 34 4 5 6 7 0.47 0.54 0.53 2 2 3 4 252.0* 238.3* 330.2* 230.0* 21.3* 36.2* CH-OH 1 13.6 10 21.6 20 22.6 30 23.6 40 23.6 50 23.6 20 No o 2 8 5 6 7 8 8 9 8 8 6 6 801.0 703.0 390.2 332.9 7.9 13.5 17.0 PT (4) (20) (6) (6) (8) (9) (10) (10) 15

XM759 Amphibious Cargo Carrier, 16,000 lb (200% Rated Pay Load)

Beauregard Island, La. 11 No o 9 9 9 10 10 n 12 13 15 15 9 9 10 11 0.81* 0.46* 0.45* 7 6 5 5 81.5* 95.8* 123.1* 67.9* 46.4* 36.5* 58.8* CH-OH Site 7 1 5.34 20 31.08 50 41.82 Bayou du Large, La. 13 No o 2* 5* 5* 7* 8* 7* 0.47* 0.54* 0.53* 2* 2* 3* 252.0* 238.3* 330.2* 230.0* 21.3* 36.2* CH-OH Site 8 1 12.40 20 23.40 50 24.40 15 No o 6 12 14 15 20 26 32 42 51 56 11 14 16 26 0.62 0.57 0.56 7 8 9 15 106.5 90.8 73.8 48.0 55.4 68.4 CH 1.1 12 0.8 12 1 1.95 20 9.60 50 15.40

(Continued)

Note: 0, 3, 6, etc., in column headings indicate depths (in inches) at which cone indexes were measured. 0-6, 3-9, etc., indicate depths of soil layer. Cone indexes shown in parentheses were taken in tussocks. * Data from adjacent test lane. )epth of Vegetation :>urface Root Tussock Water Height Depth Diam Height Spacing in. in. %Cover in. in. in. in. Type Remarks

30 7 8 3 20 Marsh Vehicle began to break through the vegetal mat on about the 4th pass, grass and was floating by the 20th pass. Test discontinued after 30 passes because it was apparent that the vehicle could complete 50 passes. Vehicle had difficulty exiting the test lane because of step heights formed at each end of the lane as a result of traffic. However, after several attempts, vehicle was able to climb out of the lane

5.0 10 10 5 Marsh Vehicle completed 50 passes without difficulty grass

16.0 - .. ------Bare Some track slip occurred on 14th pass. High track slip began about the 23d pass. Vehicle completed 50 passes

o 10 5 Sea oxeye Vehicle completed 50 passes without difficulty. Some soil accumulated on track system, but this did not hinder vehicle performance

14.4 - ...... ------Bare Vehicle appeared to be floating on 20th pass, and high track slip was experienced on subsequent passes. Vehicle completed 50 passes

0 30 7 8 3 20 Marsh On the 1st pass vehicle broke through vegetal mat and sank to float grass level. As vehicle moved forward vegetation was sheared off and built up in front of vehicle in sufficient quantity to stop forward progress at end of test lane. On the 2d pass vehicle was unable to climb on to the mat at the end of test lane; XM759 could operate forward and backward but was confined to the lane. Test was discontinued after 15 passes since it was apparent the vehicle could complete 50 passes

5.5 .. Bare .. Vehicle experienced some track slip on the 13th pass and was tilting to the left throughout the test. High track slip began on about the 20th pass. Vehicle completed 50 passes

15.6 .. Bare .. Vehiole experienced some track slip starting on the 26th pass. Vehicle completed 50 passes

10 45 5 Sea oxeye The vehicle completed 50 passes without difficulty. Some soil accumulated on the track system, but this did not hinder performance Table 3 (Concluded)

Immobili Shear graph Avg zation Data Average Cone Index of Remolding Index of Rating Cone Index of Moisture Content of Layers Dry Density of Layers Metal Smooth Rut Test Yes Pass Pass Cone Index ~ pcf USCS Grouser Rubber Depth La~ers Layers Layers ~ ~ Dry Wt Site Location and No. No. or No No. No. o _3_ 6 _9_ ~ -.l:.L 18 24 0-6 3-9 6-12 12-18 6-12 12-18 Class. _C _ 4. 0 _C_ A.".- in. Ml16 Amphibious Cargo Carrier, 7,600 lb (Empty)

Camp Wallace, Va. 2 Yes 5 o 6 13 12 8 9 10 12 16 18 20 10 n 9 10 0.42 0.19 0.32 4 3 2 3 548.6 658.2 563.0 399.1 8.5 9.7 13.6 OH-PT Site 2 1 2 4 5 7 8 8 10 14 18 20 4 5 7 9

Beauregard Island, La. 8 No o 12 15 20 30 18 18 20 20 20 21 16 22 23 19 0.46 0.32 0.44 7 9 7 8 70.2 97.7 69.5 97.4 57.3 43.8 CH-OH 1.8* 24* 0.2* 20* Site 7 1 1.2 20 8.3 50 11.9 10 Yes 16 o 8 8 9 10 10 12 12 13 14 14 8 9 10 11 0.81 0.46 0.45 6 6 5 5 81.5 95.8 123.1 67.9 46.4 58.8 CH-OH 1 3.7 15 12.7 Bayou du Large, La. Site 8 12 Yes 1 o 2 5 5 6 6 7 8 14 24 31 4 5 6 7 0.47 0.54 2 2 3 4 252.0 330.2 230.0 21.3 36.2 CH-OH 14 Yes 43 o 7 18 22 25 30 30 40 46 49 60 16 22 26 33 0.47 0.41 8 10 n 24 64.9 74.7 87.4 61.6 48.0 CH 1.2 16 0.9 16 1 0.8 20 6.1 42 13.2 23 Yes 1 o 9 9 6 8 7 8 8 10 10 10 8 8 7 8 0.34 0.64 0.56 3 4 4 4 397.8 256.9 300.7 210.8 20.6 18.2 24.8 OH

Ml16 Amphibious Cargo Carrier, 10,600 lb (100% Rated Pay Load) Camp Wallace, Va. 1 Yes 2 o 2 4 6 6 778 10 12 12 8 10 10 10 0.59 5 6 5 6 307.3 317.0 323.9 16.0 15.9 18.9 OH-Pr Site 2 (n) (15) (11) (16) (15) (13) (14) (18) (22) (23)

Mulberry Island, Va. 3 No o 14 32 30 32 38 49 72 110 101 109 25 31 33 53 0.36 0.39 Firm 9 12 13 622.0 85.2 101.0 185.1 44.7 33.8 CL-OL Site 4 1 14 25 26 32 40 46 70 108 100 108 22 28 33 52 0.9 10 1.3 20 1.7 30 2.0 40 2.4 50 14 32 32 28 34 48 70 108 98 108 26 31 31 51 2.6 Bonnet Carr~Spillway, La. 4 No o 30 40 48 42 40 40 48 34 32 41 39 43 43 43 0.67 0.54 0.60 26 26 23 26 71. 5 47.5 64.3 91·7 70.8 45.9 47.4 CH-OH Site 6 10 20 2.93.5 30 4.1 40 4.9 50 5.9 Beauregard Island, La. 5 Yes 41 o 14 18 17 26 35 21 18 21 19 20 16 20 26 25 0.42 0.29 0.37 7 7 8 9 70.3 100.3 75.6 115.6 51.5 58.4 46.0 CH-OH 1.8 24 0.2 20 Site 7 1 10 11 16 26 21 16 17 17 18 20 12 18 21 18 1.0 10 7.9 20 10.0 30 11.9 40 16.4 41 6 10 11 16 22 22 21 22 24 23 9 12 16 22 16.7 7 Yes 2 o 8 9 14 13 12 14 16 17 16 18 10 12 13 14 0.42 0.36 0.37 4 5 5 5 96.5 109.9 129.7 129.7 41.6 35.1 37.0 CH-0H 1 6 7 10 10 10 12 14 15 16 16 8 9 10 12 3.7

Bayou du Large, La. 16 Yes 27 o 4 12 18 20 22 31 40 50 48 60 11 17 20 31 0.46 5 9 12 11 84.3 71.9 61.0 64.2 64.4 CH* 1.2* 16* 0.9* Site 8 1 9 15 21 24 28 34 38 38 50 53 15 20 24 33 1.0 10 5.3 20 7.2 27 8 15 23 30 40 46 63 84 88 90 15 23 31 50 16.6 18 No o 19 31 28 26 28 26 24 26 30 35 26 28 27 26 0.52 0.48 14 15 14 12 198.2 206.7 161.9 29.7 CH-OH 1.0 16 0.5 17 1 28 28 26 26 26 24 24 27 30 32 27 27 26 25 0.4 10 1.5 20 1.5 30 1.6 40 1.6 50 28 27 24 27 27 24 23 26 28 36 26 26 26 25 1.7 22 Yes 1 o 4 5 4 4 6 6 6 8 9 9 6 5 5 6 742.6 777.8 523.5 516.1 8.6 10.2 13.7 PT (6) (12) (5) (4) (6) (6) (7) (8) (9) (10) -----~ ------'------* Data from adjacent test lane. =pth of Vegetation ll'face Root Tussock vater ~Height ~Depth Diam ~~Height Spacing in. .%Cover in. Type Remarks

o 40 90 15 Reed cane Some track slip occurred on 1st pass. Undercarriage was dragging on with wire 4th pass. Vehicle immobilized on 5th pass. No after-traffic data grass taken because ruts filled in after the vehicle was retrieved 4.8 10 10 5 Marsh Some track slip was noted on 6th pass. Undercarriage appeared to be grass dragging on 26th pass. Vehicle completed 50 passes with difficulty

6.4 Bare Vehicle experienced some slip on 1st pass. Undercarriage dragging on 8th pass. Considerable difficulty and high track slip on 11th pass.~ Immobilized on 16th pass. Vehicle retrieved by XM759

_oe__------Bare Vehicle immobilized on 1st pass, retrieved by XM759 10 45 5 Sea oxeye Soil deposited on edge of test lane began sloughing off into ruts on 18th pass. Vehicle undercarriage dragging on 23d pass. On the 37th pass, vehicle was tilting to right side and driver had difficulty keeping vehicle in original ruts. Vehicle immobilized on 43d pass o 16 80 8 Marsh Vehicle immobilized near sta 0+60 of the mobility test course on 1st grass pass

o 40 15 14 6 15 Red cane Vehicle was maneuvering into position to traverse mobility test course with wire when immobilization occurred. No after-traffic data taken because grass ruts filled in after vehicle retrieved o 42 95 6 Needlegrass Vehicle completed 50 passes without difficulty

6.0 20 100 7 Alligator Vehicle completed 50 passes without difficulty grass

5.0 10 10 5 Marsh Vehicle undercarriage started dragging on 6th pass. Vehicle dragged grass entire test lane by the 12th pass. Immobilized on 41st pass. Vehicle retrieved by XM759

6.4 .. Bare .. The driver had difficulty maneuvering the vehicle into position to traverse test lane. The vehicle experienced high track slip on 1st pass and immobilized on 2d pass. Retrieved by XM759 0 10 45 5 Sea oxeye Vehicle undercarriage began dragging on 9th pass. Soil deposited on edge of test lane began sloughing off into ruts on 7th pass. Vehicle experienced extreme difficulty on 21st pass. Immobilized on 27th pass. Vehicle was able to back out of test lane under its own power, but with difficulty 0 10 100 6 Coastal Vehicle completed 50 passes without difficulty Bermuda

o 53 8 10 3 20 Marsh The Ml16 broke through the vegetal mat and immobilized on 1st pass grass Table 4 Summary of Terrain Data, Drawbar Pull-Slip Tests

------:;:::------Draw bar Average Cone Index of Remolding Index Rating Cone Index of Dry Dens; Area Cone Index Layers of Layers Layers Layers; Site Location and No. No. o 3 6 ~ 12 15 18 24 30 0-6 3-9 6-12 12-18 0-6 6-12 12-18 0-6 3-9 6-12 12-18 0-1 0-6 6-12 12-18 0-6 6-12 Beauregard Island, La., Site 7 1 6 18 17 26 28 20 20 20 20 22 14 20 24 23 0.60 0.35 0.46 8 9 8 11 81.1 91.0 93.2 289.8 44.6 45. L

2 8 8 9 10 10 12 12 13 14 14 8 9 10 11 0.81 0.46 0.45 6 6 5 5 81.5 95.8 123.1 67.9 46.4 36.:

Bayou du Large, La., Site 8 3 21 35 38 40 36 36 34 34 36 46 31 38 38 35 0.54 0.66 0.65 16 23 25 23 109.0 84.6 52.4 47.1 48.3 67.4

4 22 30 20 21 22 16 16 22 26 31 24 24 21 18 0.46 0.62 0.60 11 13 13 11 307.8 220.9 180.7 56.2 21.8 50.~

5 3 6 8 10 12 16 20 26 34 44 6 8 10 16 0.40 0.50 0.70 2 4 5 11 477.3 468.7 85.7 61.6 20.2 50.~

6 4 20 19 20 21 24 30 33 44 50 14 20 20 25 0.53 0.67 0.68 7 12 13 17 89.7 69.6 70.3 67.4 57.4 57.;

7 122 136 66 74 80 90 88 107 114 142 108 92 73 86 1.00 0.64 0.44 108 75 47 38 18.2 32.0 33.6 33.3 83.2 83.)

8 42 64 58 56 63 60 60 56 69 82 55 59 59 61 0.78 0.73 0.53 43 32 65.8 39.5 32.0 44.8 79.6 88.(

9 8 33 19 14 12 18 22 30 31 37 20 22 15 17 0.49 0.58 0.68 10 12 9 12 225.4 157.9 114.8 54.3 36.4 47.(

Note: 0, 3, 6, etc., in column headings indicate depths (in inches) at which cone indexes were measured. 0-6, 3-9, etc., indicate depths of soil layers. Table 5 (Concluded)

Vehicle Gross Empty DBP Rolling Site Location Weight or Area Resistance DBP Slip and No. Model lb Loaded No. lb 1b %

Bayou du Large, La., M1l6 10,600 10afa 8 2600 1.0 Site 8 (Continued) pay 3600 1.0 load 4900 1.5 7200 3.5 7700 11.0 7800 27.5 7200 64.0 5600 100.0 9 1500 100 0.0 1500 0.0 2500 3.0 3300 5.0 2000 1.0 5700 11. 5 6500 10.5 3600 8.5 4700 7.0 5400 7.0 7100 17.0 6100 69.0 6400 53.0

(12 of 12 sheets) Table 5 (Continued)

Vehicle Gross Empty DBP Rolling Site Location Weight or Area Resistance DBP Slip and No. Model lb Loaded No. lb lb %

Bayou du Large, La., M116 10,600 1000/0 4 1600 4800 7.0 Site 8 (Continued) pay 6300 9.0 load. 6600 9.0 7700 18.5 8100 13.0 3300 1.5 1300 1.0 3300 3.0 4800 4.5 5300 7.0 7900 8.0 8100 100.0 5 3100 1100 40.0 1200 100.0 200 27.0 900 77.5 6 2200 2100 8.5 1500 4.0 2700 7.0 3500 11.0 4000 9·0 4600 17.0 4100 79.0 4100 100.0 300 1.0 2600 5.0 2000 2.0 3000 13.0 3300 5.0 4400 42.0 4600 31.5 4200 32.0 4100 61.5 2200 9.0 2100 0.0 7 6600 2.0 7100 1.0 7700 3.5 7600 7.0

(Continued) (11 of 12 sheets) Table 5 (Continued)

Vehicle Gross Empty DBP Rolling Site Location Weight or Area Resistance DBP Slip and No. --Model lb Loaded No. lb lb % Bayou du Large, La., Ml16 7,600 Empty 9 1200 500 0.0 Site 8 (Continued) 2800 2.0 3400 3.0 3500 2.0 4550 8.5 4900 10.0 5100 22.0 5000 56.5 4300 100.0 Beauregard Island, Ml16 10,600 100% 1 2300 500 2.0 La., Site 7 pay 800 4.0 load 3500 18.0 3000 25.0 4000 34.0 4400 44.0 3600 100.0 2800 26.0 2000 8.0 4600 38.0 4000 80.0 3500 100.0 4400 59·0 Bayou du Large, La. , Ml16 10,600 100% 3 1700 1300 1.0 Site 8 pay 1200 3.0 load 2800 3.0 800 3.0 2900 8.0 3800 4.0 4800 7.0 6200 5.5 6700 8.5 7000 19·0 6700 53.5 5700 100.0 4400 3.0 2900 0.5 3500 3.0 4400 3.5 2600 3.0 400 0.0 7200 38.0 2900 3.0 2400 1.0 4200 3.5 (Continued) (10 of 12 sheets) Table 5 (Continued)

Vehicle Gross Empty DBP Rolling Site Location Weight or Area Resistance DBP Slip and No. Model lb Loaded No. lb lb % Bayou du Large, La., Ml16 7,600 Empty 6 1800 4200 13.0 Site 8 (Continued) 3500 5.5 2700 3.5 1300 0.0 2000 1.0 3200 2.0 4100 8.5 4100 16.5 3800 31.0 3700 45.5 3600 64.0 3200 100.0 7 1100 1400 0.0 6200 33.0 4600 3.0 5100 3.5 5300 5.5 6000 13.0 5900 58.0 6600 51.5 6000 74.0 5800 100.0 5400 5.5 8 1100 800 1.0 1500 2.0 2500 2.0 4000 3.0 6500 22.5 5500 53.5 5000 76.5 100 0.0 600 0.0 1700 2.0 2600 1.5 4600 3.5 6300 10.0 5500 7.0 5800 7.0 6700 8.0 6100 22.5 5100 38.0 4600 60.0 4600 100.0

(Continued) (9 of 12 Sheets) Table 5 (Continued)

Vehicle Gross Empty DBP Rolling Site Location Weight or Area Resistance DBP Slip and No. Model Ib Loaded No. Ib Ib %

Bayou du Large, La., XM759 16,000 200% 9 1400 500 +0.0 Site 8 (Continued) pay 1100 +4.0 load 1800 +4.0 1900 +4.0 2500 +12.0 2800 +16.5 2950 +23·0 3300 +40.0 3300 +52.0 3400 +68.0 3500 +100.0 Ml16 7,600 Empty 3 1300 1800 0.0 3200 l.5 2500 l.0 3200 2.0 5000 9·0 6400 2l.0 4300 100.0 3600 5.0 4300 2.0 3300 2.0 80(J 0.0 4400 7.0 5800 16.0 5100 38.0 4500 53.5 4600 59·0 4400 77.0 4 1300 2500 0.0 2000 0.0 3200 l.0 4700 2.0 6300 5.5 6800 9.0 6300 27.5 4800 56.5 4700 72.0 4400 86.5 5 2400 600 52.0 1100 57.0 1400 82.0 1600 100.0 1400 100.0 800 85.0 (Continued) (8 of 12 sheets) Table 5 (Continued)

Vehicle Gross Empty DBP Rolling Site Location Weight or Area Resistance DBP Slip and No. Model lb Loaded No. lb lb %

Bayou du Large, La., XM759 16,000 20CJl!a 5 3800 1000 +29.0 Site 8 (Continued) pay 1700 +36.0 load 2100 +42.0 2800 +52.0 3300 +65.0 2900 +74.0 2700 +77.0 1200 +23.0 200 +4.0 6 2400 1100 +0.5 1400 +0.5 2400 +6.5 3000 +9.5 3000 +7.0 3600 +19.5 4300 +20.0 4600 +23.0 5000 +35.0 5400 +52.0 5400 +72.5 5700 +82.5 6200 +100.0 7600 +100.0 7 1000 6400 -92.0 6600 -92.0 6850 -70.0 4300 -100.0 6400 -93.0 6700 -77.0 6700 -54.0 8 1200 2400 -100.0 1900 -100.0 1100 -92.0 3600 -90.0 3000 -85.0 3500 -54.0 3700 -15.0 5400 +47.5 5000 +85.0 5100 +86.0

(Continued) (7 of 12 sheets) Table 5 (Continued)

Vehicle Gross Empty DBP Rolling Site Location Weight or Area Resistance DBP Slip and No. --Model lb Loaded No. lb lb % Beauregard Island, XM759 16,000 20(Jf/o 1 2900 3600 +23.0 La., Site 7 (Con- pay 2800 +8.4 tinued) load 4100 +30.0 3850 +40.6 3600 +18.0 3850 +21.0 3950 +15.6 4300 +57.0 4000 +92.2 4400 +76.1 2 300 -4.0 2300 +30.5 3200 +61.0 2800 +85.7 2600 +86.8 2175 +57.0 Bayou du Large, La. , XM759 16,000 20(Jf/o 3 1100 500 -6.0 Site 8 pay 1200 +3.0 load 1350 +5.5 1600 +7.5 1600 +7.5 2100 +17.5 2200 +31.0 2300 +40.0 2100 +47.5 2100 +59.0 2400 +68.0 2400 +100.0 4 1100 500 -7.0 1300 +2.5 1900 +4.0 2700 +17.5 2600 +13.5 2800 +33.0 2800 +42.0 2900 +55.0 3300 +82.5 2900 +100.0

(Continued) (6 of 12 sheets) Table 5 (Continued)

Vehicle Gross Empty DBP Rolling Site Location Weight or Area Resistance DBP Slip and No. --Model lb Loaded No. lb lb % Bayou du Large, La., XM759 13,000 100% 7 900 2700 -92.0 Site 8 (Continued) pay 400 -92.0 load 2800 -92.0 5100 -73·0 6400 -34.0 6400 -48.0 6400 -60.0 8 900 1500 -93·0 3500 -81.0 3400 -86.0 4100 -62.0 5500 +26.0 1000 -100.0 4400 -83.0 5000 +8.0 5400 +4.0 6300 +28.0 3900 -93.0 3300 -92.0 4400 -40.0 9 1200 1000 +4.0 1400 +4.0 2000 +10.0 2800 +17.5 3200 +25.0 2900 +68.0 2700 +76.0 2400 +36.0 2500 +42.0 2400 +100.0 2300 +36.0 1600 +13.5 2400 +20.0

Beauregard Island, XM759 16,000 200% 1 2900 1800 +4.0 La., Site 7 pay 2000 +4.0 load 4000 +28.0 4000 +31.0 3900 +39·0 4000 +12.0 2900 +3.5 3300 +13.0 4800 +38.0 3400 +16.0

(Continued) (5 of 12 sheets) Table 5 (Continued)

Vehicle Gross Empty DBP Rolling Site Location Weight or Area Resistance DBP Slip and No. Model lb Loaded No. lb lb %

Bayou du Large, La., XM759 13,000 1000/0 4 1200 1000 -12.0 Site 8 (Continued) pay 2000 +4.0 load 2600 +4.0 2900 +34.0 3200 +54.0 3200 +38.0 3500 +54.5 3300 +100.0 3100 +42.0 3500 +64.5 3100 +100.0 2900 +30.0 1700 -10.0 800 -10.0 500 -16.0 5 2500 2500 +28.0 2200 +27.0 2500 +52.0 3000 +72.5 2600 +100.0 2800 +68.0 2500 +100.0 1600 +16.0 1100 +11.0 2600 +20.0 1900 +71.5 2100 +100.0 6 2000 600 -1.0 2000 +4.0 2100 +4.0 2700 +11.0 3500 +16.0 2700 +21.0 3200 +16.0 4100 +26.0 4400 +67.0 5000 +77.0 5300 +84.5 4200 +36.0 600 +4.0 1500 +4.0 1600 +4.0

(Continued) (4 of 12 sheets) Table 5 (Continued)

Vehicle Gross Empty DBP Rolling Site Location Weight or Area Resistance DBP Slip and No. --Model lb Loaded No. lb lb % Beauregard Island, XM759 13,000 100% 1 1600 300 +4.0 La., Site 7 pay 800 +4.0 load 3200 +16.0 3900 +29.0 3600 +50.0 4200 +38.0 3800 +50.0 3000 +89.0 3200 +56.0 2800 +24.0 1800 +8.0 2 300 +3.5 2400 +18.0 3000 +28.0 3500 +40.0 3200 +45.0 3600 +99·0 2800 +59·0

Bayou du Large, La. , XM759 13,000 l0o% 3 1000 800 +1.0 Site 8 pay 1500 +10.0 load 2300 +21.5 2400 +39·0 2000 +52.0 2200 +34.0 2400 +60.5 2000 +16.5 900 -2.0 2900 +47.5 2200 +100.0 1000 +2.0 2100 +17.0 2500 +27.0 2000 +100.0 2100 +8.0 2600 +38.5 2500 +64.0 2000 +lOO.O 2000 +48.5

(Continued) (3 of 12 sheets) I Table 5 (Continued) Vehicle Gross Empty DBP Rolling Site Location Weight or Area Resistance DBP Slip and No. Model lb Loaded No. lb lb %

Bayou du Large, La., XM759 10,000 Empty 6 1500 1000 +3.5 Site 8 (Continued) 1900 +4.0 2800 +7.0 3000 +52.0 2500 +100.0 2300 +6.5 3000 +20.5 2900 +36.0 2900 +68.0 3400 +100.0 7 700 400 -94.0 1400 -92.0 2900 -93.0 4300 -92.0 5400 -92.0 5800 -69.0 6400 -64.0 6300 -15.0 6500 0.0 8 800 2500 -82.0 3500 -60.0 3100 -44.0 3600 -20.0 4100 +56.0 4400 +68.0 4600 +76.0 4200 +100.0 950 -96.0 1600 -92.0 2400 -92.0 9 1000 400 +0.0 1000 +0.5 1700 +4.0 1950 +23.0 2200 +47.5 2200 +76.0 1900 +100.0 1800 +31.0 1700 +12.5 2200 +52.0

(Continued) (2 of 12 sheets) Table 5 Drawbar Pull-Slip Test Results

Vehicle Gross Empty DBP Rolling Site Location Weight or Area Resistance DBP Slip and No. Model lb Loaded No. lb lb %

Bayou du Large, La. , XM759 10,000 Empty 3 700 900 -9.0 Site 8 2000 +4.0 2500 +9.5 2400 +21.5 2200 +43.0 1500 +3.5 2200 +10.0 1200 +0.5 1300 +4.0 2300 +25.0 2200 +55.5 2000 +79.0 1800 +100.0 4 800 1700 +17.5 2100 +21.0 1600 +23.0 2000 +28.0 1500 +6.5 2000 +29.0 2300 +66.0 2300 +88.0 1800 +13.5 1400 +4.0 200 +0.0 1000 +0.5 2200 +25.0 2400 +61.5 1800 +100.0 5 2200 200 +3.5 1700 +12.0 3100 +45.0 2900 +61.5 2700 +72.5 2800 +100.0 1100 +4.0 1850 +10.0 2200 +13.5 2300 +23.0

(Continued)

Note: DBP designates drawbar pull. (1 of 12 sheets) Sheargraph Depth of Vegetation ty of USCS Metal Smooth Surface Root - ~£- Soil Grouser Rubber Water Height Depth ) 12-18 ---Class. C A:... C 4..0 in. in. %Cover in. Type

24.8 CH-OH 1.8 24 0.2 20 0 10 20 5 Marsh grass 58.8 CH-OH 6 ~ Bare •

72·9 CH-OH 2.1 21 0·9 17 0 10 100 6 Coastal Bermuda grass

66.4 CH-OH 1.2 18 0.3 8 0 16 100 8 Marsh and coastal Bermuda grasses 63·6 CH-OH 12 ~ Bare • 58.3 CH 1.1 21 1.3 13 0 10 45 5 Sea oxeye 87.8 CL-CH 1.6 41 0.5 43 0 • Bare ~ 76.9 CL-CH 2.4 18 1.4 16 0 10 75 5 Marsh grass

79.6 CH-OH 6.2 19 1.8 13 0 16 100 8 Marsh and coastal Bermuda grasses

, Table 6 Summary of Data and Results of Maneuver Tests

Gross Average Cone Index of Remolding Index of Rating Cone Index of Turns Turn Time Required to Time Required to Vehicle I S Speed Weight Layers Layers Layers Direc- Radius Execute Turns Test Course Traverse Course on Tes t Cours e Si te Location and No. Vehicle Ib station o _3_ 6 0-6 l:.L 6-12 12-18 0-6 l:.L 6-12 12-18 0-6 3-9 6-12 12-18 No. tion ft Rilll 1, sec Length, ft Run 1, sec mph Remarks

Appomattox HiveT, Va., Site 1 XMf59 13,000 3+75 to 2+45 2 2 3 4 4 8 10 4 7 0.69 0.70 0·72 0·75 1 2 2 4 1 Left 145 189.0 189.0 Vehicle was unable to stay on test course Camp Wallace, Va., Mll6 7,600 1+00 to 2+00 1 2 5 8 9 12 17 18 14* 15* 12* 12* 0.59 0.56 0.54 0.56 8 8 6 7 1 Right 18 6.0 242.0 44.0 3.75 Site 2 (13) (40) (18) (17) (12) (13) (20) (22) Mll6 7,600 1+00 to 2+00 1 5 5 7 II 12 14 18 13* 16* 14* 0.59 0.56 0.54 0.56 8 9 8 8 2 Left 15 4.0 (13) (27) (23) (25) (19) (17) (20) (20) 12 18 14* 0.59 0.56 0.54 0.56 8 1 XM759 13,000 1+00 to 2+00 4 5 7 10 9 18 13* 8 8 Left 16 5.0 421.0 96.0 2·99 (21) (30) (21) (16) (14) (17) (17) (20) XM759 13,000 1+00 to 2+00 2 4 7 12 II II 18 18 12* 15* 13* 0.59 0.56 0.54 0.56 7 8 7 Right II 5.0 (15) (25) (24) (17) (15) (16) (18) (21) XM759 13,000 1+00 to 2+00 3 4 5 6 7 8 13 14 15* 16* 15* 14* 0.59 0.56 0.54 0.56 9 9 8 Right 27 34.0 (20) (32) (26) (24) (21) (20) (16) (16) XM759 13,000 1+00 to 2+00 2 3 7 10 II 12 15 16 14* 17* 14* 0.59 0.56 0.54 0.56 8 10 8 4 Left 27 4.0 (14 ) (29) (28) (24) (19) (19) (18) (18) XMf59 13,000 8+00 to 9+00 2 3 3 3 4 5 12 12 8* 8* 8* 0.70 0.61 0.52 0.50 6 4 1 Left 29 H.O 380.0 90.0 2.88 (9) (15) (16) (12) (9) (9) (16) (17) 14 14 12* 14* 12* 0.70 0.61 0.52 0.50 8 6 2 XM759 13,000 8+00 to 9+00 2 4 5 8 7 9 13* 9 7 Left 35 (14) (22) (21) (19) (16) (14 ) (19) (19) 6 10 19 20 ll* 10* 10* Chickahominy Hiver, Va., XM759 13,000 2+72 to 3+39 5 6 6 7 Left 26 350.0 90.0 Site 3 (16) (18) (14) (14) (17) (19) (24) (25) 2.65 XM759 13,000 2+72 to 3+39 5 6 6 6 7 10 19 20 ll* 10* 10* 2 Right 34 10.0 (16) (18) (14) (14) (17) (19) (24) (25) XM759 13,000 8+70 to 9+80 3 7 9 10 10 10 17 6 9 10 II 1 Left 58 19·0 240.0 94.0 1.74 XM759 13,000 8+70 to 9+80 3 7 9 10 10 10 17 6 9 10 II 2 Right 17 10.0 Mulberry Island, Va., Mll6 10,600 0+00 to 1+00 16 28 30 56 62 84 97 ll4 25 38 49 60 0·30 0.32 8 12 17 1 Right 18 5.0 340.0 54.0 Site 4 Mll6 10,600 0+00 to 1+00 22 52 50 68 80 106 104 ll6 41 57 66 123 0·30 0.32 12 18 22 2 Left 15 5.4 Ml16 10,600 0+00 to 1+00 16 44 72 86 96 149 ll7 125 44 67 85 135 0.30 0.32 13 21 29 3 Left 14 5.0 Mll6 10,600 0+00 to 1+00 15 44 78 106 173 161 ll4 129 46 76 ll9 159 0.30 0.32 14 24 40 4 Right 22 3.0 XM759 13,000 0+00 to 1+00 16 28 30 56 62 84 97 ll4 25 38 49 60 0.30 0.32 8 12 17 1 Right 22 4.0 38.8 5.85 66 12 22 2 XM759 13,000 0+00 to 1+00 22 52 50 68 80 106 104 ll6 41 57 123 0.30 0.32 18 Left 12 2.0 333.0 0+00 to 1+00 16 44 72 86 96 149 ll7 125 44 67 85 135 13 21 29 3 Left XM759 13,000 0.30 0.32 12 2.8 XM759 13,000 0+00 to 1+00 15 44 78 106 173 161 ll4 129 46 76 ll9 159 0.30 0.32 14 24 40 4 Right 16 2.6 XM759 13,000 9+00 to 10+00 4 15 II 12 14 13 13 15 17* 20* 18* 16* 0.52 0.52 0.46 9 10 9 9 1 Right 29 17.0 420.0 129.0 2.22 (12) (31) (28) (25) (21) (20) (17) (17) XM759 13,000 9+00 to 10+00 8 28 27 19 17 18 14 17 18* 0.52 0.52 0.51 0.46 14 15 12 9 2 Left 18 4.0 (19) (36) (34) (21) (17) (19) (17) (18) 6 XM759 13,000 9+00 to 10+00 4 5 4 6 8 9 13 13 ll* ll* 10* 10* 0.52 0.52 0.51 0.46 6 Left ll.O (15) (23) (16) (ll) (ll) (ll) (17) (18) Messick, Va., Mll6 10,600 6+00 to 7+00 37 50 23 20 68 49 103 190 37 31 37 53 0.40 0.34 0.28 0.26 15 II 10 14 1 Left 10 2.9 356.0 36.6 6.64 42 0.40 0.34 0.28 0.26 20 2 Right Site 5 Ml16 10,600 6+00 to 7+00 62 71 62 46 38 35 62 84 65 60 49 26 14 II 27 4.2 Mll6 10,600 6+00 to 7+00 138 300+ 300+ 300+ .. ?45 300+ 0.40 0.34 0.28 0.26 3 Right 25 3.6 Mll6 10,600 6+00 to 7+00 63 68 13 7 10 10 99 146 48 29 10 47 0.40 0.34 0.28 0.26 19 10 3 12 4 Left 15 3.6 14 1 XM759 13,000 6+00 to 7+00 37 50 23 20 68 49 103 190 37 31 37 53 0.40 0.34 0.28 0.26 15 II 10 Left 13 3.3 326.0 39·0 5.70 26 2 Right XMf59 13,000 6+00 to 7+00 62 71 62 46 38 35 62 84 65 60 49 42 0.40 0.34 0.28 0.26 20 14 II 15 3. 6 13,000 6+00 to 7+00 138 300+ 300+ 300+ .. • 245 300+ 0.40 0.34 0.28 0.26 3 Right 10 3.4 XM759 12 XM759 13,000 6+00 to 7+00 63 68 13 7 10 70 99 146 48 29 10 47 0.40 0.34 0.28 0.26 19 10 3 4 Left 19 3.4 60 52 50 43 46 56 53 53 49 0.68 0.66 0.65 0.66 38 35 34 32 1 Right 19 333.0 4.77 Eormet Carr~,La., XM759 13,000 2+00 to 0+85 53 54 53 3.9 2+00 to 0+85 37 43 37 40 37 37 33 32 39 40 38 36 0.68 0.66 0.65 0.66 27 26 25 24 2 Left 29 4.6 Traction loss; vehicle side skid in turn Site 6 XM759 13,000 20 , XM759 13,000 2+00 to 0+85 45 61 53 44 42 38 31 33 53 53 46 37 0.68 0.66 0.65 0.66 36 35 30 24 3 Left 3.6 4 Right 18 ' XM759 13,000 2+00 to 0+85 43 54 59 57 54 44 46 55 52 57 57 47 0.68 0.66 0.65 0.66 35 38 37 31 6.0 Mll6 10,600 1+00 tD 1+80 43 54 59 57 54 44 46 55 52 57 57 47 0.68 0.66 0.65 0.66 35 38 37 31 1 Left 12 3.3 221.0 41.5 Mll6 10,600 1+00 to 1+80 45 61 53 44 42 38 31 33 53 53 46 37 0.68 0.66 0.65 0.66 36 35 30 24 2 Right 14 5.5 24 Mll6 10,600 1+00 to 1+80 37 43 37 40 37 37 33 32 39 40 38 36 0.68 0.66 0.65 0.66 27 26 25 3 Right 16 5.0 Ml16 10,600 1+00 to 1+80 60 53 54 53 52 50 43 46 56 53 53 49 0.68 0.66 0.65 0.66 38 35 34 32 4 Left 17 5.1 22 16 14 1 Beauregard Island, La., XM759 13,000 3+00 to 4+00 23 35 28 21 18 18 37 24 29 28 19 0.56 0.50 0.43 0.47 9 9 Left 20 2.0 410.0 36.6 7.64 33 0.50 0.43 0.47 28 16 2 Right Site 7 XM759 13,000 3+00 to 4+00 43 73 47 48 40 31 41 37 54 56 44 0.56 30 19 29 4.2 Traction loss; vehicle side skid in turn XM759 13,000 3+00 to 4+00 10 41 39 24 21 21 19 18 30 35 28 24 0.56 0.50 0.43 0.47 17 17 12 II 3 Right 27 2.5 Traction loss; vehicle side skid in turn 24 0.43 0.47 26 26 14 4 Left XM759 13,000 3+00 to 4+00 14 78 48 31 19 19 17 19 47 52 33 0.56 0.50 II 32 2.5 Turn radius was affected by vehicle ruts from n Mll6 10,600 3+00 to 4+00 23 35 28 21 18 18 37 24 29 28 22 19 0.56 0.50 0.43 0.47 16 14 9 9 1 Left 28 3.2 320.0 30.2 Ml16 10,600 3+00 to 4+00 43 73 47 48 40 31 41 37 54 56 44 33 0.56 0.50 0.43 0.47 30 28 19 16 2 Right 23 3.5 Mll6 10,600 3+00 to 4+00 10 41 39 24 21 21 19 18 30 35 28 24 0.56 0.50 0.43 0.47 17 17 12 II 3 Right 33 3.5 Traction loss; vehicle side skid in turn Ml16 10,600 3+00 to 4+00 14 78 48 31 19 19 17 19 47 52 33 24 0.56 0.50 0.43 0.47 26 26 14 4 Left 23 2.6 41 0.41 0.48 0.56 0.61 20 23 II25 1 Right Bayou du Large, La., XM759 13,000 8+51 to 9+51 30 40 42 40 42 40 49 53 37 41 41 15 18 2.5 492.0 8.47 21 2 Left Site 8 XM759 13,000 8+51 to 9+51 18 35 35 31 31 37 48 60 29 34 32 34 0.41 0.48 0.56 0.61 12 16 18 27 8.0 Traction loss; vehicle side skid in turn XM759 13,000 8+51 tD 9+51 13 36 21 26 27 26 24 28 23 28 25 25 0.41 0.48 0.56 0.61 9 13 14 15 4 Right 27 4.0 Traction loss; vehicle side skid in turn Mll6 10,600 8+51 to 9+51 30 40 42 40 42 40 49 53 37 41 41 41 0.41 0.48 0.56 0.61 15 20 23 25 1 Right 18 3.5 33.0 7.50 Mll6 10,600 8+51 to 9+51 18 35 35 31 31 37 48 60 29 34 32 34 0.41 0.48 0.56 0.61 12 16 18 21 2 Left 22 6.5 12 16 14 Mll6 10,600 8+51 to 9+51 26 31 23 24 22 25 23 27 27 26 29 23 0.41 0.48 0.56 0.61 II 3 Left 19 5· 5 Mll6 10,600 8+51 to 9+51 13 36 21 26 27 26 24 28 23 28 35 25 0.41 0.48 0.56 0.61 9 13 14 15 4 Right 27 4.5 6 8 0.65 0.64 0.64 0.47 3 4 4 1 Right ·72 Morgan's Island, La., XM759 13,000 3+50 to 4+50 3 4 4 6 7 8 12 13 4 5 3 86.5 180.0 ll5.0 1.07 Vehicle was 1ll1able to stay on test course 8 0.65 0.64 0.64 0.47 4 2 Left Site 10 XM759 13,000 3+50 to 4+50 3 3 5 5 6 7 10 12 4 4 5 3 3 3 59 28.5 Vehicle was 1ll1able to stay on test course 1 Right XM759 13,000 5+66 to 6+65 25 20 9 9 9 9 9 10 18 13 9 9 0.43 0.40 0.38 0.56 8 5 3 5 19 6.0 350.0 4.79 Chicken Island, La., 1 XM759 13,000 5+66 to 6+65 20 12 10 10 9 8 9 9 14 II 10 9 0.43 0. .0 0.38 0.56 6 4 4 5 2 Left 28 12.2 Site II 8 7 4 4 Left 26 XM759 13,000 5+66 to 6+65 13 II 8 8 7 7 10 II II 9 0.43 0.40 0.38 0.56 5 3 3 5.4 8 7 0.43 0.40 0.38 0.56 4 4 4 Right 25 XM759 13,000 5+66 to 6+65 II 14 9 8 7 7 10 10 II 10 5 3 5.2

Note: 0, 3, 6, etc., in column headings indicate depths (in inches) at which cone indexes were measured. 0-6, 3-9, etc., indicate depths of soil layers. Cone i nflex sho' ...n in parentheses were measured in tussocks. * Average of cone indexes measured in depressions and tussocks. ------

Table 7 Summary of Soil Data, Water Exit Test at Bayou du Large, La.

Sheargraph Average Cone Index of Moisture Content of Dry Density of USCS Metal Smooth Test Station La~ers Layers, ! Dry Wt Layers, pcf Soil Grouser Rubber ~ ~ No. Vehicle Location o £ 0-6 3-9 -12 12-18 0-6 1:..2...... :l:? 12-18 0-6 6-12 12-18 ~....£.... C ....£.... 1 XM759 Bank 136 188 76 58 56 80 86 82 83 106 133 107 63 25.9 28.1 40.8 49.5 93.4 78.8 70.8 CH 1.2 29 2.3 17 Underwater 8 15 22 24 31 36 42 61 79 86 15 20 26

2 XM759 Bank 94 115 91 88 89 76 74 72 85 105 100 98 89 80 36.1 34.7 51.4 83.3 CH 23 0.8 7 Underwater 13 39 51 56 59 81 100 119 139+ 166+ 34 49 55 80

3 XM759 Bank 124 116 74 63 51 53 68 87 102 110 105 84 63 57 CH 2.0 25 0.8 8 Underwater 8 23 34 59 59 91 101 115 141 159 21 39 51 84

4 XM759 Bank 175 207 79 58 70 86 133+ 164+ 174+ 180 154 115 69 96+ 32.5 32.0 72.2 51.8 85.1 54.0 68.7 CH 6.0 o 1.2 7 Underwater 10 30 31 36 36 46 64 86 101 114 24 32 34 47 32.5 32.0 72.2 51.8 85.1 54.0 68.7

XM759 Bank 21 25 36 47 60 62 71 89 100 108 27 36 48 64 32.5 32.0 72.2 51.8 85.1 54.0 68·7 CH 1.8 25 0.2 16 Underwater 11 30 41 56 64 73 82 88 105 121 27 42 54 73 32.5 32.0 72.2 51.8 85.1 54.0 68.7

2 M116 Bank 94 115 91 88 89 76 74 72 85 105 100 98 89 80 36.1 34.7 51.4 83.3 84.3 69.4 49.9 CH 23 0.8 7 Underwater 13 39 51 56 59 81 100 119 139 166 34 49 55 80

3 M1l6 Bank 124 116 74 63 51 53 69 87 102 110 105 84 63 57 CH 2.0 25 0.8 8 Underwater 8 23 34 59 59 91 101 115 141 159 21 39 51 84

6 M116 Bank 15 50 61 74 84 87 104 120 139 169 42 62 73 92 CH 2.8 18 1.7 14 Underwater 11 17 20 22 26 29 16 20 23

7 M1l6 Bank 102 230 167 210 148 147 158 197 200+ 173+ 166 202 175 151 CH 2.0 17 1.0 16 Underwater 13 15 21 27 37 58 16 21 28

8 Ml16 Bank 95 193 100 82 63 67 75 80 58 82 129 125 82 68 CH 14 1.0 18 Underwater 22 41 39 38 38 34 31 38 34 39 38 34

Note: 0, 3, 6, etc., in column headings indicate depths (in inches) at which cone indexes were measured. 0-6, 3-9, etc., indicate depth of soil layer. Table 8 Summary of Soil Data, Mobility Tests

Sheargraph Average Cone Index of Remolding Index Rating Cone Index of Moisture Content of Layers Dry Density of USCS Metal Smooth Cone Index Layers of Layers Layers %Dry Wt Layers, pcf Soil Grouser Rubber Site Location and No. Station o _3_ 6 _9_ 12 ~ 18 24 ~ 36 0-6 3-9 6-12 12-18 0-6 6-12 12-18 0-6 3-9 6-12 12-18 0-6 6-12 12-18 ~ ~ 4" ~ 4.0

Appomattox River, Va., 6+50 to 5+75 1 2 3 3 4 4 6 19 10 2 3 3 5 0.69 0.72 0.75 1 2 2 4 163.1 137.6 135.9 172.2 36.2 35.8 29.7 MH Site 1 5+75 to 2+45 2 2 3 4 4 8 10 10 10 2 3 4 7 0.69 0.72 0.75 1 2 3 5 163.1 137.6 135.9 172.2 36.2 35.8 29·7 MH 2+45 to 2+25 13 13 16 17 15 15 14 16 17 18 14 15 16 15 0.40 0.66 0.70 6 8 11 10 244.4 157.0 104.0 121.6 29.0 42.4 40.2 MH CampWallace, Va., o+ooio2+80------2-- 5---8 9 9 -8 11 12 14 15 14* 16* 16* 14* 0.59 0.54 0.56 8 9 9 8 307.3 317.0 323.9 272.9 16.0 15.9 18.9 OH-PI' Site 2 (15) (28) (27) (23) (21) (19) (18) (19) (20) (21) 2+80 to 3+00 4 5 6 6 13 13 13 12 17 12 5 6 8 13 0.62 0.46 0.38 3 3 4 5 454.9 269.7 136.8 183.9 19.8 18.4 27.3 OH-PI' (32) (81) (61) (51) (40) (25) (25) (20) (21) (22) 3+00 to 3+37 112 3 345 6 8 10 1 2 3 4 0.44 0.48 0.47 o 1 1· 2 303.3 279·3 297.4 280.0 19.5 18.3 18.4 OH-PI' 3+37 to 4+00 3 6 6 8 8 12 12 16 17 19 10* 13* 13* 14* 0.44 0.48 0.47 4 6 6 7 303.3 279.3 297.4 280.0 19.5 18.3 18.4 OH-PI' (8) (17) (21) (20) (15) (17) (15) (19) (22) (22) 4+00 to 5+42 2 5 7 6 7 7 10 15 13 13 12* 14* 12* 10* 0.70 0.52 0.50 8 9 6 5 548.3 571.3 332.7 346.5 8.9 15.9 14.8 OH-PI' (15) (26) (20) (19) (14) (11) (15) (16 ) (17) (19) 5+42 to 6+00 114 5 866 11 14 15 9* 10* 0.70 0.52 0.50 4 4 5 5 548.3 571.3 332.7 346.5 8.9 15.9 14.8 OH-PI' (8) (8) (10) (10) (16) (13) (10) (14 ) (13) (13) 6+00 to 7+24 1235555 10 12 13 5* 7* 0.70 0.52 0.50 4 4 3 4 548.3 571.3 332.7 346.5 8.9 15.9 14.8 OH-PI' (9) (7) (8) (9) (9) (8) (9) (13) (13) (16) 7+24 to 9+00 2 3 3 346 7 12 13 14 10* 10* 9* 0.70 0.52 0.50 7 6 4 4 762.0 662.7 367.8 477.7 7.7 13.7 11. 8 OH-PI' (12) (22) (17) (12) (11) (14) (12) (17) (19) (20) Chickahominy River, Va., 0+00 to 2+72 4911 11 12 ~ ~ 18 8 10 11 PI' Site 3, Course 1 2+72 to 4+02 5 6 6 6 7 10 14 17 19 20 11* 9* 10* PI' (16) (18) (14) (14) (17) (19) (22) (23) (24) (25) 4+02 to 8+24 5 J 8 10 10 11 12 14 16 16 7 8 9 11 PI' [ggJ l§2J .. Water ------<- .. 8+24 to 8+70 4 7 8 9 12 14 17 18 18 6 8 9 12 PI' 8+70 to 9+80 3 7 9 10 9 12 13 17 17 6 9 9 11 PI' Site 3, Course 2 0+00 to 1+20 4 4 9 10 14 12 13 6 8 11 13 PI' 1+20 to 3+04 4 5 10 10 10 10 10 6 8 10 10 PI' 3+04 to 3+29 4 7 8 9 12 14 17 18 18 6 8 9 12 PI' 3+29 to 4+11 4 6 10 10 12 12 16 17 7 9 10 12 PI' Mulberry Island, Va., 0+00 to 1+50 28 36 48 54 68 80 91 113 115 124 37 46 57 80 0.30 0.34 11 15 19 743.6 274.7 75.6 74.8 19.4 82.0 74.8 CL-OH Site 4 1+50 to 2+40 66 124 156 159 132 122 124 179 211 228 115 146 149 126 1.00 0.44 0.56 115 105 66 71 52.0 19.6 20.0 21.2 104.1 107.8 105.8 CL-OH 5.0 18 0.5 24 2+40 to 3+34 28 56 72 96 120 107 102 121 142 153 52 75 96 110 0.46 0.43 0.46 24 33 41 51 658.3 96.7 36.4 41.4 41.1 83.5 77.1 CL-OH 3+34 to 3+40 12 15 23 28 35 45 52 82 107 122 17 22 29 44 0.46 0.43 0.46 8 10 12 20 658.3 96.7 36.4 41.4 41.1 83.5 77.1 CL-OH 3+40 to 4+20 22 45 66 87 112 113 98 106 123 142 44 66 88 108 0.46 0.43 0.46 20 29 38 50 CL-OH 4+20 to 7+47 50 97 115 144 165 178 191 220 272 272 87 119 141 178 0.94 0.61 1.00 82 85 86 178 45.2 18.3 20.1 23.3 92.6 102.5 CL 0.2 37 33 7+47 to 7+58 27 55 66 90 114 89 98 220 274 176 49 70 90 100 0.94 0.61 1.00 46 55 55 100 45.2 18.3 20.1 23.3 92.6 102.5 CL 7+58 to 11+00 3 4 7 8 9 9 9 11 11 12 10* 10* 12* 12* 0.52 0.51 0.46 5 5 6 6 339.8 393.8 450.5 359.7 13.6 13.1 15.2 OH (12) (17) (16) (13) (17) (15) (16) (21) (19) (21) 11+00 to 11+35 3 3 346 7 7 8 10 10 3 3 4 7 0.52 0.51 0.46 2 2 2 3 339.8 393.8 450.5 359.7 13.6 13.1 15.2 OH 11+35 to 13+53 3 6 8 9 10 13 12 12 14 14 11* 13* 14* 15* 0.52 0.51 0.46 6 7 7 7 339.8 393.8 450.5 359.7 13.6 13·1 15.2 OH (11) (18) (20) (17) (18) (16) (19) (18) (20) (19) Messick, Va., Site 5 0+00 to 1+96 ~ ~ ~ ~ ~ ~ ~ 37 41 52 34 52 57 34 --- Sand--- SP 1+96 to 2+08 78 51 34 22 26 33 28 46 50 59 54 36 27 29 0.28 0.65 0.46 15 17 18 13 OL-PI' 2+08 to 3+09 36 55 34 25 21 33 51 70 75 79 42 38 27 35 0.28 0.65 0.46 12 17 18 16 280.2 326.5 183.4 18.4 16.8 26.9 OL-PI' 5.1 28 0.2 20 3+09 to 3+39 7 42 46 62 57 49 51 93 111 134 32 50 55 52 --- Sand--- SP 26 3+39 to 5+44 68 77 43 56 73 53 63 76 96 154 63 59 57 63 0.43 0.40 0.62 27 25 23 39 49.7 38.6 36.1 68.8 81.8 82.9 OL-PI' 8.0 23 o 5+44 to 5+56 4 5 8 10 12 19 27 44 300 300 6 8 10 19 0.24 0.34 0.34 1 3 3 6 OL-PI' 54 146 168 173 44 46 66 0.40 0.28 0.26 18 5+56 to 7+13 71 30 32 53 62 81 38 13 13 17 93.3 44.3 33.2 42.6 75.4 77.2 OL-PI' 4.0 32 0.6 16 7+13 to 7+68 14 21 50 88 160 141 181 171 206 255 28 53 99 161 ---- Sand- OL-PI' 7+68 to 10+00 82 45 47 63 75 69 61 76 154 204 58 52 62 68 0.40 0.28 0.26 23 18 17 18 44.3 93.3 33.2 42.6 75.4 77.2 OL-PI' 4.0 32 0.6 16 Bonnet Carre Spillway, La., 0+00 to 0+85 14 37 57 59 54 50 45 47 44 38 36 51 57 50 0.60 0.58 0.56 22 30 33 28 86.2 75.8 44.1 80.6 52.3 78.0 51.7 CH-OH 1.1 18 1.1 12 Site 6, Course 1 0+85 to 1+80 ~ 44 ~ ~ ~ % ~ 55 55 55 47 56 61 63 0.82 0.67 0.58 39 41 41 37 59.7 68.2 43.1 82.9 56.4 77.5 53.4 CH-OH 2.0 31 1.2 24 1+80 to 4+49 ~ ~ ~ 46 ~ ~ ~ 63 41 26 46 48 45 42 0.54 0.63 0.73 25 28 28 31 68.7 57.2 51.4 44.0 63.9 70.4 76.7 CH-OH 3.4 21 o 28 4+49 to 4+67 148 201 198 218 214 198 205 182 206 210 206 1.00+ 1.00+ 1.00+ 182 206 210 206 CH 4+67 to 4+96 4 8 9 11 12 12 15 18 23 7 9 11 13 0.53 0.59 0.64 4 5 6 8 CH 4+96 to 6+00 34 35 30 32 26 32 36 33 28 28 33 32 29 31 0.53 0.59 0.64 17 18 17 20 87.5 91.1 52.7 41.7 47.0 69.0 78.7 CH 3.1 26 2.0 20 6+00 to 6+34 83 101 80 88 71 68 57 67 58 48 88 90 80 65 0.57 0.54 50 50 43 37.9 35.0 46.2 65.2 72.4 59.1 CH-OH 3.0 32 1.3 18 6+34 to 7+12 34 41 39 42 52 45 61 41 40 38 38 41 44 53 0.52 0.52 0.51 20 21 23 27 95.2 165.1 59.2 42.0 CH-OH 3.7 25 1.7 15 7+12 to 7+67 62 52 60 50 54 50 50 40 58 35 58 54 55 51 0.44 0.62 0.57 26 29 34 29 103.8 214.0 74.0 57.1 20.3 52.7 62.2 CH-OH 2.2 32 1.4 22 7+67 to 9+00 ~ ~ ~ ~ ~ ~ ~ 36 45 31 39 38 40 41 0.50 0.50 0.59 20 19 20 24 97.5 81.3 45.5 48.3 CH-OH 0.4 33 2.0 19 Site 6A, Course 2 0+00 to 2+54 76 105 71 56 62 65 73 66 65 55 84 77 63 67 0.32 0.58 0.52 27 35 37 35 85.2 49.8 52.6 41.0 67.1 66.9 79.6 CH-OH 1.4 17 0.2 9

(Continued) Note: 0, 3, 6, etc., in column headings indicate depths (in inches) at which cone indexes were measured. 0-6, 3-9, etc., indicate depths of soil layers. Cone indexes shown in parentheses were measured in tussocks. . [] Readings taken in vegetation clumps. * Indicates average of cone indexes measured in depressions and tussocks. Table 8 (Concluded)

Sheargraph Average Cone Index of Remolding Index' Rating Cone Index of Moisture Content of Layers Dry Density of USCS Metal Smooth Cone Index Layers of Layers Layers %Dry wt Layers, pcf Soil Grouser Rubber Site Location and No. Station 0 _3_ 6 _9_ 12 18 24 36 0-6 6-12 12-18 0-6 6-12 12-18 0-6 --.!2.- -l£... 3-9 3-9 6-12 12-18 0-1 0-6 6-12 12-18 0-6 6-12 12-18 Class. C A:... C ~ 12 Beauregard Island, La., 0+00 to 2+25 31 27 27 25 25 22 28 29 31 23 28 26 24 0.40 0.63 0.36 9 15 16 9 98.6 52.5 64.4 104.4 67.8 58.2 42.8 CH-OH 1.0 0.2 12 142 17 Site 7, Course 1 2+25 to 2+70 64 146 215 222 252 . 217 152 152 151 142 194 230 204 Sand 22.4 - 23.3 23.9 23.6 102.6 96.4 96.1 SF 1.8 30 1.3 19 2+70 to 4+44 35 43 36 26 21 40 34 28 32 26 38 35 28 32 0.56 0.43 0.47 21 18 12 15 32.6 37.1 138.7 71.0 83.2 33.2 57.0 CH-OH 1.8 20 0.2 24 4+44 to 4+78 8 10 12 22 18 22 20 18 20 25 10 15 17 20 0.58 0.28 0.40 6 6 5 8 56.5 152.2 49.2 55.4 31.1 72.3 68.9 0.8 26 0.5 21 4+78 to 4+84 28 24 22 20 22 25 29 32 26 29 25 22 21 25 0.72 0.43 0.32 18 13 9 8 56.6 86.1 75.0 112.4 45.9 51.5 40.5 OH-CH 5.0 26 2.1 24 4+84 to 6+34 36 25 22 22 16 26 17 18 22 19 28 23 20 20 0.62 0.47 0.35 17 12 9 7 51.4 234.4 98.9 71.8 20.7 43.2 56.4 CH-OH 1.4 24 0.5 20 6+34 to 9+83 7 17 20 19 18 18 17 16 :L6 15 15 19 19 18 0.50 0.44 0.53 8 9 8 10 168.9 157.9 120.0 176.4 29.9 34.6 28.6 CH-0H 2.0 16 0.7 23 9+83 to 10+13 24 39 34 16 15 16 15 15 16 18 32 30 22 15 Sand 0.58 0.68 Sand 17 13 10 25.9 26.9 33.9 25.6 53.6 86.8 96.5 CH-OH 1.3 27 0.2 21 10+13 to 10+45 13 21 42 47 50 35 18 15 15 15 25 37 46 34 0.33 0.49 0.38 8 15 23 13 60.0 78.5 45.9 51.5 74.7 SM 10+45 to 11+50 17 24 31 25 22 15 14 16 17 18 24 27 26 17 0.62 0.50 0.34 15 15 13 6 85.7 195.4 69.4 265.4 24.9 56.0 19.6 CH-SM 2.2 17 0.8 11 Site 7, Course 2 0+00 to 1+91 48 81 114 146 193 206 232 234 271 275 81 114 151 210 ___ Sand ---- 29.8 27.6 28.0 28.9 93.5 92.7 93.6 SF 1.8 28 0.5 23 1+91 to 2+98 31 67 74 102 92 109 100 94 70 75 57 81 89 100 0.45 0.38 0.14 26 34 34 14 31. 7 30.4 26.3 35·9 88.2 95.0 80.9 SF 3.6 26 1.3 23 2+98 to 3+18 8 22 23 23 30 25 22 24 27 29 18 23 25 26 0.40 0.36 0.48 7 9 9 12 76.3 51.2 62.2 97.9 66.2 59·0 45.2 CH-CL-ML 3+18 to 4+82 10 16 35 26 24 27 40 66 88 92 20 26 28 30 0.46 0.39 0.30 9 11 11 9 56.8 75.4 59.1 67.8 53.6 60.0 58.7 CH-CL-ML 1.6 22 0.4 26 4+82 to 4+93 78 166 153 124 82 42 47 37 39 36 132 144 120 57 0.95 0.79 0.44 126 125 95 25 9.8 19.2 44.5 66.0 56.5 67.4 55.4 CH-CL-OH 4.6 30 0.8 34 4+93 to 5+32 5 9 10 15 16 20 18 21 23 31 8 11 14 18 0.46 0.35 0.34 4 4 5 6 46.0 71.1 62.4 226.6 54.7 56.6 21.2 CH-OH 0.5 29 0.8 23 5+32 to 6+82 12 33 23 30 30 19 21 22 23 22 23 29 28 23 0.46 0.35 0.34 11 12 10 8 46.0 71.1 62.4 226.6 54.7 56.6 21.2 CH-OH 1.0 23 1.5 90 Bayou du Large, La., 0+00 to 2+00 14 26 13 13 10 10 12 12 14 15 18 17 12 11 0.32 0.64 0.56 6 8 8 6 397.8 256.9 300.7 210.8 20.6 18.2 24.8 OH 5.4 21 2.1 17 Site 8 2+00 to 3+13 10 29 19 16 16 23 32 35 38 41 19 21 17 24 0·53 0.70 0.59 10 13 12 14 168.4 204.4 101.9 64.1 22.8 44.6 60.0 CH 2.0 35 1.9 18 3+13 to 3+82 5 10 15 16 16 22 30 36 49 52 10 14 16 23 0.63 0.62 0.56 6 9 10 13 89.1 81.9 63.9 58.6 50.2 59.3 64.3 CH 1.4 8 0.5 7 3+82 to 7+86 8 14 14 24 26 40 44 53 62 63 12 17 21 30 0.50 0.58 0.38 6 9 12 11 104.0 89.8 55.8 42.0 47.3 66.9 75.8 CH 7+86 to 10+08 11 34 33 30 31 31 30 30 32 40 26 32 31 31 0.41 0.56 0.61 11 15 17 19 143.2 145.9 85.6 49.7 31.2 50.0 70.2 CH-OH 1.7 17 0.1 10 10+08 to 11+16 4 7 9 13 15 20 23 28 37 45 7 10 12 19 0.62 0.56 0.47 4 6 7 9 212.1 173.7 65.8 57.9 29.6 59·7 64.4 CH-OH 11+16 to 12+36 10 13 11 8 9 10 11 12 14 15 11 11 9 10 0.32 0.50 0.48 4 4 4 5 253.4 577.4 439.1 455.3 8.2 12.9 12.4 OH 3.6 21 0.5 16 Minor Canal, La., 0+00 to 1+71 18 10 10 11 13 16 18 18 16 20 13 10 11 16 0.52 0.49 0.32 7 5 5 5 225.5 331.4 909.3 896.5 20·9 6.0 5·7 OH-PT 0.8 20 1.3 32 Site 9 1+71 to 2+74 13 10 11 10 12 12 13 13 13 14 11 10 11 12 0.52 0.49 0.32 6 5 5 4 OH-PT 2+74 to 2+98 19 9 9 11 17 20 22 21 22 22 12 10 12 20 0.42 0.46 0.44 5 4 6 9 351.1 327.3 657.1 843.6 16.2 8.4 6.9 OH-PT 3.1 29 1.6 22 2+98 to 3+92 3 4 9 7 12 15 18 18 20 21 5 7 9 15 952.4 884.5 647.4 679.7 6.5 8.6 8.3 PT 3+92 to 5+00 14 4 4 8 12 15 18 20 21 23 7 5 8 15 1173.8 733.5 1078.6 760.6 6.8 4.9 7.5 PT Morgan's Island, La., 0+00 to 1+10 4 7 9 7 7 7 9 11 12 13 7 8 8 8 0.40 0.49 0.42 3 4 4 3 61.1 53.2 71.6 94.1 67.2 52.6 45.1 CH Site 10, Course 1 1+10 to 2+80 3 15 17 16 20 21 19 19 18 18 12 16 18 20 0.20 0.32 0.44 2 4 6 9 60.3 37.8 44.3 40.4 82.3 76.2 78.8 CH 2+80 to 5+17 2 3 4 4 5 6 6 7 8 8 3 4 4 6 0.65 0.64 0.47 2 3 3 3 140.0 121.6 115.5 233.5 38.3 40.3 21.8 CH 5+17 to 6+52 5 7 7 8 9 9 8 8 9 10 6 7 8 9 0.38 0.71 0.52 2 4 6 5 251.4 222.1 307.2 481.3 23.2 24.6 12.0 OH Site lOA, Course 2 0+00 to 1+20 5 7 8 8 9 9 10 12 16 100+ 7 8 8 9 0.50 0.40 0.50 4 4 3 4 67.6 55.0 47.5 52'.9 66.4 73.0 68.0 CL

0+00 0+80 Chicken Island, La., to 5 8 8 8 8 8 9 11 12 12 7 8 8 8 0.54 0.60 0.56 4 5 5 4 190.7 186.1 141.3 127.1 27.1 33.5 3B:0 OH 3.6 28 0.7 25 Site 11 0+80 to 1+50 10 12 13 11 11 10 10 11 12 12 12 12 12 10 0.60 0.50 0.56 7 7 6 6 160.8 159.1 131.8 161.6 29.6 36.2 30.8 OH 2.0 16 1.6 24 1+50 to 4+69 4 7 6 7 6 7 8 10 9 10 6 7 6 7 0.72 0.46 0.59 4 4 3 4 216.8 221.3 119.2 160.6 23.1 39.2 30.9 CH 4+69 to 7+55 9 13 10 8 7 7 7 8 8 9 11 10 8 7 0.43 0.38 0.56 5 4 3 4 105.0 192.6 202.9 151.6 26.9 25.0 32.9 OH 0.5 13 0.6 16 7+55 to 10+00 4 5 4 4 4 6 6 8 8 9 4 4 4 5 0.66 0.68 0.62 3 3 3 3 78.3 124.7 141.7 133.7 36.6 33.8 35.7 CH 10+00 to 10+95 6 15 15 12 10 9 10 11 13 13 12 14 12 10 0.48 0.42 0.39 6 6 5 4 140.0 142.9 164.0 175.7 33.4 30.0 28.6 CH-OH 2.2 18 1.1 28

, Table 9

Summary of Terrain Data, Mobility Tests

_____ Hydrologic-Vegetation Association (Vegetation l-in. >2.5-in. >5.5-in. >8.5-in. Height % Depth Height Base Height Spacing Angle Spacing Site Location and No. Station No. TyJJe* No. Terrain Description Diam Diam Diam Diam in. Cover in. in. Diam, in. in. in. deg ft Appomattox Mud Flat, Va. 6+50 to 5+75 ld,2d,3d,4d-3,3,3,1-[lJ 39 River >25 >25 >25 >25 Site 1, Course 1 5+75 to 2+45 ld,2d, 3d,4d-3, 3,3,1-1- [1] 46 Barren, mud flat >25 >25 >25 >25 1 <21 >163 >150 2+45 to 2+25 1,3a(1)-1,3,3,1-1~[2J5 Elevated mud flat 10 10 18-120 <10 >150 >150

Camp Wallace, Va. 0+00 to 2+80 1, 3a(2)-1, 3,3,1-1 [2J 6 Flat, tidal marsh 14 6 15 15 5 <12 >150 >150 Site 2, Course 1 2+80 to 3+00 1,3b(2)-1,3,3,1-1[1] 4 Flat, tidal marsh 19 11 60 18 10 150 >150 3+00 to 3+37 ld,2d,3d,4d,-3,2,3,1-1[1] 24 Linear depression >25 >25 >25 >25 22 148 >150 3+37 to 4+00 1,3a(2)-1,3,3,1-1[lJ 2 Flat, tidal marsh 27 10 30 13 1 <12 >150 >150 4+00 to 5+42 1,3b(2)-1,3,3,1-1[2] 8 Flat, tidal marsh 24 10 36 14 4 <12 >150 >150 5+42 to 7+24 1,3b(2)-1,3,3,1-1[U 4 Flat, tidal marsh 21 3 26 13 6 <12 >150 >150 7+24 to 9+00 1,3 a (2)-1,3,3,1-1[U 2 Flat, tidal marsh 21 5 24 10 6 <12 >150 >150 Chickahominy River, Va. 0+00 to 2+72 ld,2d,3d,4d-l,3,3- 1 -[1-P] 36 River >25 >25 >25 >25 Site 3, Course 1 2+72 to 4+02 1,3a(2)-1,3,3,1-1[1-P] 14 Impounded river marsh 24 30 20 20 150 >150 4+02 to 8+24 2,2-3,2,3-1-[1-pJ 45 Floating marsh 36 8+24 to 8+70 ld,2d,3 d ,4d-l,3,2-1-[1-pJ 35 Drainageway >25 >25 >25 >25 8+70 to 9+80 2,2-3,2,3-1-[1-P] 45 Floating marsh 36 Site 3, Course 2 0+00 to 1+20 ld,2d,3d,4d-l,3,3-1-[1-pJ 36 River >25 >25 >25 >25 1+20 to 3+04 2,2-3,2,3-1-[1-P] 45 Floating marsh 3+04 to 3+29 ld,2d,3d,4d-l,3,2-1-[1-P] 35 Drainageway >25 >25 >25 >25 3+29 to 4+11 2,2-3,2,3-1-[1-P] 45 Floating marsh

Mulberry Island, Va. 0+00 to 1+50 1,3a(1)-1,3,3,1-3[2J 5 Abandoned channel marsh o <12 >150 >150 <1·5 Site 4, Course 1 1+50 to 2+40 1,3b(1)-1,3,3,1-5[5J 13 Edge of sand ridge in abandoned channel marsh 2 <12 >150 >150 <1.5 2+40 to 3+34 1,3b(1)-1,3,3,1-4[4J 12 Abandoned channel marsh 2 <12 >150 >150 <1·5 3+34 to 3+40 ld,2d,3 d ,4d-l,3,3,1-3[2] 24 Linear depression >25 >25 >25 >25 6 170 >150 <1·5 3+40 to 4+20 1 ,3a(2) -1, 3,3,1-4[3] 9 Abandoned channel marsh 12 6 7 2 150 >150 <1.5 4+20 to 7+47 la,2b, 3c ,4c-3,3,3 ,1-5 [5J 21 Ancient beach ridge 6 6 15·5 15.5 72 >150 >150 <1·5 7+47 to 7+58 lc,2d,3d,4d-3,2,3,2-4[5] 22 Foreslope of beach ridge 20 >25 >25 >25 48 149 >150 <1·5 7+58 to 11+00 1,3 a (2)-1,3,3,1-1[1] 2 River, tidal marsh 20 9 18 14 6 150 >150 <1.5 11+00 to 11+35 ld,2d,3d,4d-2,3,3,1-1[lJ 27 Linear depression >25 >25 >25 >25 12 170 >150 <1.5 11+35 to 13+53 1,3 a (2)-1,3,3,1-1[2J 6 River, tidal marsh 17 10 19 9 8 <12 >150 >150 <1·5 Messick, Va. 0+00 to 1+96 ld,2d,3d,4d-l,1,3-3[1-S] 33 River >25 >25 >25 >25 Site 5, Course 1 1+96 to 2+08 ld,2d,3d,4d-l,3,3,1-3[3J 26 Beach >25 >25 >25 >25 >150 <1.5 2+08 to 3+09 1,3b(1)-1,3,3,1-3[3J 10 Flat, drained marsh >150 <1·5 3+09 to 3+39 ld,2d,3 d ,4d-2,3,3,1-3[1-S] 31 Linear depression >25 >25 >25 >25 >150 <1.5 3+39 to 5+44 1,3b (1 )-1,3,3,1-3[3] 10 Flat, drained marsh >150 <1·5 5+44 to 5+56 ld,2d,3 d ,4d-l,3,3,1-1[lJ 23 Linear depression >25 >25 >25 >25 >150 <1·5 5+56 to 7+13 1,3b (1 )-1,3,3,1-3 [2] 7 Flat, drained marsh >150 <1·5 7+13 to 7+68 ld,2d,3d,+d-2,2,1,3,1-4[1-S] 30 Linear depression >25 >25 >25 >25 >150 <1.5 7+68 to 10+00 1,3b (1 )-1, 3, 3, 1-4[3J 10 Flat, drained marsh >150 <1.5

* A terrain type is identified by an array of groups of class numbers or class number-letter combina tions. In the array each group or factor family is shown in the following order: (a) vegetation (stem diameter and stem spacing) or hydrologic-vegetation association (water depth and plant descriptions); (b) surface geometry (step height, approach angle, obstacle spacing, and slope) or hydrologic geometry (approach angle, water depth, and channel width); and (c) surface composition (soil mass strength). In the array, where the first group consists of two numbers or one number and one number-letter combination, a hydrologic-vegetation association is indicated. Where the second group consists of three numbers, a hydrologic geometry is indicated. (See Appendix C for individual c~assesused for each factor family.) For example, terrain type la,2a,3d,4d-l,3,3,1-4 represents the following factors and values: vegetation--la (>l-in.-diam stems spaced 0-8 ft apart), 2a (>2.5-in.-diam stems spaced 0-8 ft apart), 3d (>5.5-in.-diam stems spaced >25 ft or lacking), 4d (>8.5-in.-diam stems spaced >25 ft or lacking); surface geometry--l (step height is 150 deg), 3 (spacing value of >150 ft), and 1 (slope is

Fine-Grained Soil Organic Soil Clean Sand RCI 3- to 9-in. Depth CI 3- to 9-in. Depth CI 0- to 6-in. Depth Class RCI Range Class CI Range Class CI Range I [1] 0-6 [l-P) 0-35 [l-S) <50 [2J 7-15 [2-pJ 36-50 [2-SJ 51-100 [3J 16-30 [3-p] >50 [3-SJ 101-150 [4J 31-50 [5J >50 , ~SurfaceComposition Critical Hydrologic Geometry t- La.yer Approach CI RCI CI CI Angle Depth Width 6-12 3-9 3-9 0-6 deg ft ft Vegetation Type

3 2 176 >36 >60 None 3 2 None 16 8 Wire grass

16 9 Reed cane and wire grass 30 19 Wire grass 3 1 None 13 6 Elephant ears and reed cane 12 9 Wire and marsh grass 9 4 Reed cane with various marsh grasses 7 6 Reed cane

11 10 None 10 9 Wire grass 9 8 >165 3 >60 Various water plants, lilies, etc. 9 8 140 5 46 None 9 9 >165 3 >60 Various water plants, lilies, etc. 11 8 120 5 >60 River depth at sta 0+00, none 10 8 >165 3 >60 Various water plants, lilies, etc. 9 8 140 4.0 25 None 10 9 >165 3 >60 Various water plants, lilies, etc.

57 15 Needlegrass 149 105 Broomstraw grass 96 33 Needlegrass with broomstraw grass 29 10 None 88 29 None 141 85 Pine, 100 ft tall, 16.8-in. diam It 90 55 Scrubs, 6-10 ft tall, 1- to 2-in. diam 12 5 Needlegrass 4 2 None J 14 7 Wire grass

57 34 170 34 >60 River depth at sta 0+00, none 1 27 17 None 27 17 Various marsh grasses 55 32 None 57 25 Marsh grasses 10 3 None 46 13 Marsh grasses 99 28 None 62 18 Marsh grasses I

Table 9 (Concluded)

Hydrologic-Vegetation Association (Vegetation <1-in. Diam) Non-Tussock Tussock Surface Geometry Vegetation Spacing, ft Root Root Water Step Approach Obstacle Terrain >l-in. >2.5-in. >5·5-in. >8.5-in. Height % Depth Height Base Height Spacing Depth Depth Height Angle Spacing Slope Site Location and No. Station No. Type No. Terrain Description Diam Diam Diam Diam ina Cover in. in. Diam, in. in. in. in. in. in. deg ft deg

Bonnet Carre Spillway, La. 0+00 to 0+85 1,3b(1)-1,3,3,1-3[3] 10 Cleared swamp 18 100 6 24 <12 >150 >150 <1.5 Site 6, Course 1 0+85 to 1+80 1,3b(1)-1,3,3,1-4[4] 12 Cleared swamp 22 100 5 4 <12 >150 >150 <1.5 1+80 to 4+49 1,3b(1)-1,3,3,1-3[3] 10 Cleared swamp 20 100 7 8 <12 >150 >150 <1.5 4+49 to 4+67 1,3b(1)-2,3,3,1-5[5] 18 Road 4 50 4 0 18 174/ 165 >150 <1.5 4+67 to 4+96 2,3b(1)-2,2,2-1-[l] 37 Bar ditch 10 100 42 4+96 to 6+00 1, 3b(1)-1, 3,3, 1-3 [3] 10 Cleared swamp 30/72 80/20 6/- 3 <12 >150 >150 <1.5 6+00 to 6+32 1,3a(1)-2,3,3,1-4[4] 47 Cleared swamp 40 90 6 8 20 >150 >150 <1.5 6+32 to 7+12 1,3b(1)-1,3,3,1-3[3] 10 Cleared swamp 16 90 7 10 150 >150 <1.5 0 7+12 to 7+67 1,3b~1)-1,3,3,1-3[3]10 Cleared swamp 30 75 5 8 <12 >150 >15 <1·5 7+67 to 9+00 1,3b 1)-1,3,3,1-3[3] 10 Cleared swamp 26 50 7 2 150 >150 <1·5 Site 6A, Course 2 0+00 to 1+35 la,2a,3d,4d-l,3,3,1-4[4] 20 Cleared swamp 1·7 1.7 >25 >25 2 <12 >150 >150 <1·5 1+35 to 2+54 1,3 a(1)-1,3,3,1-4[4] II Cleared swamp 48-60 90 8-10 4 <12 >150 >150 <1·5

Beauregard Island, La. 0+00 to 2+25 Id,2d,3 d,4d-3,3,3-3[2] 42 Bay >25 >25 >25 >25 Site 7, Course 1 2+25 to 2+70 Id,2d,3d,4d-2,3,3,2-5[3-S] 32 Beach >25 >25 >25 >25 19 175 >150 2 2+70 to 4+44 1,3b(1)-1,3,3,1-3[3] 10 Marsh flat 10 90 6 1 <12 >150 >150 <1·5 4+44 to 4+78 Id,2d,3d,4d-2,3,3,1-2[1] 27 Linear depression >25 >25 >25 >25 18 176/169 >150 <1.5 4+78 to 4+84 1,3a(1)-2,2,3,1-2[2] 15 Dike 38 80 8 0 18/14 131/148 >150 <1.5 0 4+84 to 6+34 1,3b~1)-1,3,3,1-2[2]7 Marsh flat 30 100 7 1 <12 >150 >15 <1.5 6+34 to 9+83 1,3b 1)-1,3,3,1-2[2] 7 Mud flat 6 10 2 1 150 >150 <1.5 9+83 to 10+13 Id,2d,3d,4d-l,3,3,1-2[3] 25 Marsh flat >25 >25 >25 >25 25 80 3 <12 >150 >150 <1.5 10+13 to 10+45 Id, 2d, 3d,4d- 3,1,2,2- 3- [2J 40 Drainage channel >25 >25 >25 >25 10+45 to II +50 1,3b(1)-1,3,3,1-3[2] 7 Marsh flat 24 90 8 0 <12 >150 >150 <1.5 Site 7, Course 2 0+00 to 1+91 Id,2d,3d,4d-3,3,3-5-[2-S] 43 Bay >25 >25 >25 >25 1+91 to 2+98 1,3a(1)-2,1,3,3-4[4] 16 Beach ridge 120/36 40/50 12/8 0 20 95 >150 <1.5 2+98 to 3+18 Id,2d,3d,4d-l,3,3,1-2[2] 24 Linear depression >25 >25 >25 >25 -- 10 178 >150 <1.5 3+18 to 4+82 1,3b(1)-1,3,3,1-3[2] 7 Marsh flat 8 80 6 2 <12 >150 >150 <1.5 4+82 to 4+93 1,3 a(1)-3,3,3,1-5[5] 17 Dike 48 50 >12 0 30 164/158 >150 <1·5 4+93 to 5+32 Id,2d,3d,4d-l,3,3,1-1[1] 23 Linear depression >25 >25 >25 >25 <12 >150 >150 <1·5 5+32 to 6+82 1,3b(1)-1,3,3,1-3[2] 7 Marsh flat 20 60 5 2 <12 >150 >150 <1.5

Bayou du Large, La. 0+00 to 2+00 1, 3a(1)-1, 3, 3, 1-1 [2] 5 Bayou marsh 53 95 8 0 <12 >150 >150 <1.5 Site 8, Course 1 2+00 to 3+13 1,3b(1)-1,3,3,1-2[2] 7 Bayou marsh 16 80 8 2 <12 >150 >150 <1.5 3+13 to 3+82 1,3b(1)-1,3,3,1-2[2] 7 Bayou marsh 10 45 5 4 <12 >150 >150 <1.5 3+82 to 7+86 Id,2d,3d,4d-3,1,3,3-2-[2] 41 Bayou >25 >25 >25 >25 7+86 to 10+08 1,3b(1)-1,3,3,1-3[2] 7 Bayou marsh 10 100 6 1 <12 >150 >150 <1·5 10+08 to II +16 Id,2d,3d,4d-l,3,2,3,3,1-1[1] 28 Depression >25 >25 >25 >25 <12 140/167 >150 <1.5 1l+16 to 12+36 1,3b(1)-1,3,3,1-1[1] 3 Bayou marsh 26 95 6 3 <12 >150 >150 <1.5

Minors Canal, La. 0+00 to 1+71 1,3a(1)-1,3,3,1-1[l] 1 Marsh flat 96 60 5 0 <12 >150 >150 <1.5 Site 9, Course 1 1+71 to 2+74 Id,2d,3d,4d-l,3,3- 1-[1] 34 Minors canal >25 >25 >25 >25 2+74 to 2+98 1,3b (1)-1,3,3,1-1[1] 3 Natural levee with spoil with spongy matte 30 40 3 3 <12 >150 >150 <1·5 2+98 to 3+92 i,2-1,3,3,1-1-[1-P] 44 Flotage 8-20 45 17-28 <12 >150 >150 <1.5 3+92 to 5+00 1,2-1,3,3,1-1- [l-PJ 44 Flotage 26 80 17-28 <12 >150 >150 <1.5

Morgan's Island, La. 0+00 to 1+10 Id,2d,3d,4d-3,3,3- 1-[1] 39 River >25 >25 >25 >25 Site 10, Course 1 1+10 to 2+80 1,3 a (1)-1,3,3,1-2[1] 1 Natural levee 72 90 6 4 <12 >150 >150 <1·5 2+80 to 5+17 Id,2d,3d,4d-l,3,3,1-1[1] 23 Mud flat >25 >25 >25 >25 <12 >150 >150 <1·5 5+17 to 6+52 1,3 a (1)-1,3,3,1-1[1] 1 River marsh 60 10 4 6 <12 >150 >150 <1·5 Site lOA, Course 2 0+00 to 1+21 la,2a,3d,4d-l,3,3,1-1[1] 19 Willow swamp 1.25 1.25 >25 >25 15 <12 >150 >150 <1.5 Chicken Island, La. 0+00 to 0+80 1,3a(1)-1,3,3,1-1[1] 1 Bayou marsh 96;48 40/50 10/6 6 <12 >150 >150 <1·5 Site 11, Course 1 0+80 to 1+50 1,3a(1)-1,3,3,1-1[2] 5 Bayou marsh 10 80 12 4 <12 >150 >150 <1·5 1+50 to 4+69 Id,2d,3d,4d-l,3,3- 1-[1] 34 Bayou >25 >25 >25 >25 4+69 to 7+55 1,3a(1)-1,3,3,1-1[1] 1 Island marsh 48/30 40/60 7/5 5 <12 >150 >150 <1·5 7+55 to 10+00 Id,2d,3d,4d-3,1,3- 1-[l] 38 Bayou ------10+00 to 10+95 1,3a(1)-1,3,3,1-1[l] 1 Bayou marsh 48/36 65/30 6/4 0 <12 >150 >150 <1·5

I Surface Composition Critical Hydrologic Geometry Layer Approach Angle Depth Width deg ft ft Vegetation Type Alligator grass Alligator grass Alligator grass Small grasses 3·5 29 Floating alligator grass, 100% cover Alligator grass with wax myrtle Ragweed Alligator grass Alligator grass with 5% wax myrtle Alligator grass with 5% wax myrtle Wax myrtle 10 ft high, 1-3/4-in. diam; minor quantity of alligator grass Cattails and ragweed

177 >4.5 >60 None 142 None Sea oxeye None Ragweed, marsh grasses, and wax myrtle Marsh grass (oyster grass) Stilted mangrove knees, dead Mangrove bushes; 1/2-in. diam, average spacing 7 in. 170/ 130 48 32 None Marsh grass with mangrove bushes 20 in. high 81 177 >4.5 >60 None Reed cane and various grasses None Sea oxeye Wax myrtle with grasses None Marsh grass (oyster grass) 12 Marsh grass 17 Coastal Bermuda 16 Sea oxeye 21 176/112 11.9 404 None 31 Coastal Bermuda 12 None 9 Marsh grass dense matte 11 Reed cane, alligator grass 11 148/145 7.5 103 None 12 Alligator grass, bull tongue, marsh grass, and various water hyacinths 9 Various water plants forming a spongy surface matte underlain by water 8 Similar to that above, but voids are more frequent and vegetation is increasing in height 8 3.5 >60 At sta 0+00 18 Water lilies and small willows 4 None 8 Alligator grass and various marsh grasses 8 Willows, 20 ft tall, 2.5-in. diam (avg)

8 Reed cane with wire gr~ss 12 Reed cane, dense 6 105/143 12·3 319 None 8 Elephant ears, alligator grass 4 170 29 245 None 12 Wire grass, elephant ears with Some reed cane. Small, woody stems are >25 ft apart Table 10

SWlIInary o-f Data and Speed lest Results

Appomattox River, Va., Site I, Course 1

Vehicle XM759 MI16 Ml16 Weight, Ib 13,000 10,600 7600 Driver Horton Scroll Scroll Run No. 1 1 2 Starting point , station 6+50 6+50 £+50 Ter- rain Station ~ Speed, mph

6+50 to 5+75 39 1* 1* 5+75 to 2+45 46 1** 2+45 to 2+25 5

Camp Wallace, Va. 2 Site 2, Course 1

t Vehicle XM'159 XN75 .1 XM759 XM759 XM759 XM7~9 XM'(59 XM'759 XM759 MI16 Ml16 Weight, Ib 13,000 l3,OClO 13,000 13,000 13,000 10,000 10,000 10,000 10,000 /600 7600 Driver Harley Rafferty Harley Horton Horton Eubar.Jcs Eub1:;!.nks Birnschein Birnschein Tryon Horton Run No. 1 2 3 4 5 6 '( 8 9 1 2 Starting point 2 station 0+00 9+00 0-1{)() 9+00 0+00 0+00 9+00 0+00 9+00 0+00 0+00 Ter- rain Station Type Speed, mph

0+00 to 2+80 6 4.44 6.58 4.34 3,32 5.97 7.64 7.61 5.78 4.11 8.02 5.02 2+80 to 3+00 4 1.24 1.95 2.27 1. 70 1.70 1. 70 1.95 3.41 2.73 8.02 3.41 3+00 to 3+37 24 3.15 2.29 3.15 5.61 5.05 1.80 3.51 1.94 2.52 1* 1* 3+3'( to 4+00 2 4.30 6.14 3.58 3.31 5.00 4.21 4.39 4+00 to 5+42 8 4.21 4.84 3.34 5.15 1•• 5° 4.32 6.5'1 4.44 3.87 5+42 to 6+00 4 2.83 6.59 3.29 4.39 3.96 3.88 4.88 2.86 4.04 6+00 to 7+24 4 3.02 4.45 1.96 3.53 2.56 3.58 5.95 5.52 3.58 7+24 to 9+00 2 5.46 3.53 2.35 3.33 2.19 4.03 3.87 5.89 3.66

Overall speed, mph 3.86 4.68 3.00 3.89 4.02 4.20 5.30 4.66 3.78

Chickahominy River, Va., Site 3, Course 1

VehicJ e XM759 XM759 XM759 XM759 XM759 XM759 XM759 XM759 M1l6 Weicht, Ib 13,000 13,000 13,000 13,000 10,000 10,000 10,000 10,000 7600 Dr iver Harley Harley Clark Clark Harley Harley Horton Horton Harley ., Ihm No. 1 3 4 5 6 7 8 1 Starting point, station 0+00 9+&J 0+00 9+80 0+00 9+1.30 0+00 9+80 0+00 Ter- rain Station Type Speed, mph

0+00 to 2+72 36 2.85 3.14 3.31 3.20 3.38 3.20 2.95 3.25 It 2+'(2 to 4+02 14 3.41 3.06 3.41 4.66 3.06 1.85 4.92 7.39 4+02 to 8+24 45 2.88 3.00 2.80 3.35 2.64 2.25 3.84 4.79 8+24 to 8+70 35 3.14 2.61 2.61 4.48 3.1 11 1.85 2.85 4.48 8+70 to <)+&J 45 2.89 3.26 3.12 3.75 3.00 2.35 4.41 5.00

Overall speed, mph 2.95 3.0'.; 3.02 3.52 2.93 2.36 3.64 ',.43

Chickahominy River, Va., Site 3, Course 2

Vehicle XM'(59 XM759 XM759 XM759 XM759 XM'/59 XM759 XM759 Weight, Ib 13,000 13,000 10,000 10,000 10,000 10,000 13,000 13,000 Driver Harley Harley Harley Harley Perea Perea Clark Clark Harley Run No. 1 2 3 4 5 6 7 8 1 Starting point, station 0-1{)() 4+11 0+00 4+11 0+00 4+11 0+00 4+11 0+00 Ter- rain Station Type Speed, mph

O-l{)() to 1+20 36 3.27 3.27 3.62 4.31 4.33 4.43 3.15 3.27 It 1 +20 to 3+04 45 2.61 2.73 4.94 4.88 4.05 4.41 3.49 2.99 3+04 to 3+29 35 3.41 1.14 3.41 3.34 3.70 3.79 3.41 2.43 3+29 to 4+11 45 1.93 1.93 4.66 3.21 2.87 3.49 2.30 3.11

Overall speed, mph 2.61 2.46 4.31 4.17 3.'19 4.1) 3.0'/ 3.05

( Continued)

Note: I indicates vehicle was immobilized. The causes of the immobilizations are noted on each page of table. ~- Immobilization occurred beeausc:: soil strength was below the VCII reqUirement. l'he XM'/59 encountered a soft cIa,',' terrace at station 2+45 creatine a 114_in. step height between the plane where the wheel track was operating and the top of the bank. The vehicle was able to back out of the immobilization. t Ml16 immobilization was caused by low soil strength and frontal motion resi:otancc caused by vegetation. (1 of 4 sheets) Table 10 (Continued)

Bclllnet Carre Spillway, L3.., Site 6A, Course 2

Vehicle XM759 XM759 XM759 XM759 XM759 XM759 XM759 XM759 Weight, 1b 13,000 13,000 13,000 13,000 10,000 10,000 10,000 10,000 Driver Harley Harley Perea Perea Perea Perea Harley Harley Run No. 1 2 3 4 5 6 7 8 Starting point, station OffiO 2+54 0-1{)0 2+54 0-1{)0 2+54 0-1{)0 2+54 Ter- rain Station Type Speed, mph

O;{)O to 1+35 20 2.56 6.14 5.'15 7.54 6.57 9. 20 9.20 9.59 1+35 to 2+54 11 2.82 6.37 5.12 6.70 5.60 7.84 8.71 6.88

Overall speed, mph 2·69 6.26 5.44 7.12 6.08 8.52 8.96 8.12

Vehicle Ml16 Ml16 Ml16 Mu6 Ml16 M116 Ml16 Ml16 Weight, Ib 10,600 10,600 10,600 10,600 7600 7600 7600 7600 Driver Harley Harley Tryon Tryon Perea Perea Eubanks Eubanks Run No. 1 I 2 3 4 5 6 7 Starting point, station 0-1{)0 2+54 0-1{)0 2+54 0-1{)0 2+54 0-1{)0 2+54 Ter- rain Station Type Speed, mph

0+00 to 1+35 20 2.22 2.49 '7.36 11.51 11.51 13.54 13.95 14.38 1 +35 to 2+54 11 4.61 3.27 7.84 9.80 11.20 13.07 15.68 13.0'7

Overall speed, mph 2.91 2.80 '1.58 10.66 11.36 13.30 14.70 13.75

Beauregard Island., ill., Site 7 t Course 1

Vehicle =159 XM759 XM759 XM759 XM'159 XM759 =159 XM759 Ml16 MU6 Ml16 Ml16 Weight, 1b 13,000 13,000 13,000 13,000 10,000 10,000 10,000 10,000 10,600 10,600 10,600 7600 Driver Harley Harley Barrow Barrow Birnschein Birnschein Perea Perea Harley Harley Harley Harley Run No. 1 2 3 4 5 6 7 8 1 2 2 3 Start i ng point I station OffiO 11+50 OffiO 11+5° 0-1{)0 11+5° 0+00 11+50 0-1{)0 9+83 O-I{)Q 0-1{)0 Ter- rain Station Type Speed, mph

O;{)O to 2+25 42 8.77 13.34 10.23 12.27 11.80 13.95 H.8o 13.95 6.53 7.31 9.03 2+25 to 2+70 32 9. 64 13.04 9.64 11.08 11.67 12·32 10.56 13.04 8.32 13.00 10.40 2+70 to 4+44 10 10.79 10.79 16.95 10.79 23.73 11.86 12.49 11.63 10.79 10.06 12.11 4+44 to 4+78 27 8.18 6.35 5.75 6.14 9.20 7.67 6.57 6.82 7.58 Itt Itt I< 4+78 to 4+84 15 5.54 5.91 3.41 5.91 6.82 8.86 4.43 5.54 5.36 6.25 4+84 to 6+34 7 8.18 11.36 9.30 11.36 9.74 12.78 10.23 13.64 9.30 10.77 6+34 to 9+83 7 11. 78 13.22 12.86 11.90 13.22 13.60 12.02 13.22 11.61 9.84 9+83 to 10+13 25 'J.74 6.82 13.11 7.58 11.36 11.36 11.36 8.97 7.84 10+13 to 10+45 40 5.45 5.45 5.07 6.82 7.88 11.08 7.88 8.86 Itt 10+45 to 11+50 7 7.16 7.95 6.39 8.95 9.55 11.93 8.42 11.01

Overall. speed, mph 9.54 11.69 10.21 10.65 11.63 12.63 10.95 12.03

Beauregard Island, MOl Site 7, Course 2

Vehicle XM'I59 XM759 XM759 XM759 XM'159 XM759 XM759 XM759 XM759 M116 Mu6 Ml16 Ml16 Ml16 Weight, 1b 13,000 13,000 13,000 13,000 10,000 10,000 10,000 10,000 10,000 10,600 7600 '1600 7GJo 7600 Driver Harley Harley Eubanks Eubanks Clark Clark Clark C)ark Clark Harley Harley Harley Harley Harley Run No. 1 2 3 4 5 6 7 8 9 1 2 3 4 5 Starting point t station 0-1{)0 6+82 O-I{)Q 6+82 0-1{)0 6+82 Q-I{)O 6+82 0-1{)0 OffiO 0-1{)0 6+82 0-1{)() 6+82 Ter- rain Station Spced mph != t O;{)O to 1+91 43 6.45 8.57 6.20 8.69 8.69 9.87 8.69 5.54 5.32 6.06 5.01 1 +91 to 2+98 16 6.29 8.59 5.61 7.45 § 9.12 8.59 8.29 6.35 7.30 9.12 9· 73 2+<:-18to 3+18 24 6.82 9.74 8.53 8.27 8.53 9.10 8.53 8.80 6.14 5.58 8.19 7.67 3+18 to 1++82 7 8.11 8.61 8.29 8·95 13.98 10.17 ".32 10.36 7.99 8.61 8.95 8·95 4+82 to 4+93 17 3.70 3.97 4.3'1 I§§ 4.37 4.20 4.20 4.37 4.37 3.82 4.24 1. 59 4.77 4+<=.:3to 5+32 23 5.65 5.49 4.82 9.47 4.65 7.19 4.40 6.59 4.12 1* 4.00 2.54 3.96 1# 5+3,-J to 6+82 7 9.47 8.67 9·30 9.47 9.30 6.82 10.23 9.74 9.30 7.87 7.06 10.23 7.31

Overall speed, mph 6.94 8.52 7.09 8.08 8.71 9.05 8.52 6.42 5.64 6.82

( Continued)

.)1 Immob:Uization occurred because "oil strength was below the VCII requirement. t: ::~~~~~~:~~~~'w=~i~a~~:~n~\:~ss~~~o:t~:~g~~n~:t~~I6Yr~;~;~~:~n~~stT~:h~~~;:s ~bleto make the first pass with difficulty. U The MllE. inunobilized when it nosed into the bank of a drainae;eway. The vehicle was able to back out of the immobilization. §§: Te,t was terminated because test vehicle personnel were physically shaken as vehicle jumped step hei~ht. § The XM7~/)was unable to negotiate dike slope. By the ninth pass, water splashed on the firm c1a.y surface of the dike during previous passes caused traction loss tJetween the tires and the wet soil. # Immobilization occurred because soil strength was below the VCl} requirement. Vehicle was able to make the first three pa"ses with difficulty. (3 of 4 sheets)

LEGENDFOR VEGETATIONSYMBOLS

Trees or scrub vegetation greater than 10 f't high

Wax myrtle or mangrove bushes

Reed, cane, or cattails

Ragweed

Tussocks

Water hyacinths or elephant ears

Tii Sea oxeye

xx Alligator grass

Grasses (wire, needle, broomstraw, marsh, or coastal bermuda) \\ \1\\1 0+00 1+00 2+00 3+00 10

0 Site 1. Side view of test course ~ from sta 1+00 to 2+75 Lo. RCI w u 8 <{ u.. 0: -5 :::> III 0: W ~ <{ ~ 0 ~ -10

0 w 0: APPOMATT 0: w COURS Lo. -0:W Z 5 Site 1. Side view of test course Site 2. Aerial view 0 ~ from 2+75 5+00 <{ sta to > W ...J W o

RCI RCI 9 3 -5

-10

Site 2. Looking from sta 0+00 Site 2. Looking from sta to 9+00 3+00 to 3+50 STATIONS 4+00 ~+oo 8+00 7+00 8+00 9+00 10+00 I I I I I I I

RCI 2

OX RIVER, VA. I, SITE I

RCI RCI RCI RCI Rei I 6 9 4 6

CAMP WALLACE, VA. MOBILITY TEST COURSE COURSE I, SITE 2 VIEWS AND PROFILES APPOMATTOX RIVER, VA., SITE I CAMP WALLACE, VA., SITE 2 PLATE I I 0+00 1+00 2+00 5,-1 I I

0- \ CHICKAHOMINY RIVER

-5 ~ Site 3, course 1. Looking from Site 3, course 1. Looking from l- LL. sta 1+00 to 9+80 sta 2+80 to 9+80 ... W CI U 10 ~ a:: -10 ::> -- II)

a:: w ~ ~ 0 I- 0 w a:: a:: w LL. w a:: z 5- Site 3, course 1. Side view of Site 3, course 1. Side view of 0 test course from sta 4+50 to test course from sta 9+10 to i= ~ 6+50 8+90 W -l W {~()(] 0 0 f"\ 0 (l DCCICC C( 0 00 - -/l]~ ~ CHICKAHOMINY RIVER T ~ -I-

-5-

CI CI 8 8 -IO~ COURSE 2 Site 3, course 2. Side view of Site 3. Aerial view test course from sta 1+50 to 2+90 STATIONS 3+00 4+00 ~+OO 6+00 7+00 8+00 9+00 10+00 I I I I I I I I

CI CI CI CI 9 8 8 9

COURSE I

CI Cl 8 9

MOBILITY TEST COURSE VIEWS AND PROFILES ( CHICKAHOMINY RIVER, VA. SITE 3, COURSES I AND 2 I PLATE 2 I 0+00 1+00, 2+00, 3+00, 20 r

I!>

10 Site 4. Looking from sta 0+00 Site 4. Looking from sta 4+00 t ~ to 4+00 to 7+50 .. lal o

~ ;~~!1~;~~1~~111;~1~1;1;1~;1;1;1;1~1~1~1~1;1t1;11j~1~11111;1;11;r1t~ilil1;tjjmmlttrtfmmrrrfJtrmtIlt~@f~lrrtmImmWif~IIIliJII~~rI%rm~trtf{rmmfII IX :> !> l II) IX lal !< RCI I RCI I RCI IRCII ~ I 5 105 33 10 J29 g o o III IX IX lal ~ lal IX oZ -!> t= ~ lal -' Site 4. Looking from sta 7+50 Site 4. Aerial view lal to 13+86 !>

o &4CKRIVER

CI RCI RCI CI 34 17 17 32 -!> 1

Site 5. Looking from sta 1+50 Site 5- Looking from sta 5+50 to 10+00 to 10+00 STATIONS 4+00 ~+OO 8+00 7+00 8+00 SHOO 10+00 11+00

RCI 85

RCI ReI RCI ~~ 5 2

MULBERRY ISLAND,VA. COURSE I! SITE 4

RCI RCI CI RCI 2~ 13 28 18

MESSICK, VA. COURSE I, SITE 5 J

12+00 13+00 14+00 I~+OO I I I I

Rei 7

MOBILITY TEST COURSE VIEWS AND PROFILES MULBERRY ISLAND, VA., SITE 4 MESSICK, VA., SITE 5

PLATE 3 0+00 1+00 2+00 10

o Site 6. Looking from sta 0+00 Site 6. Looking from sta 4+65 to 4+50 to 5+00 ... UJ IJ ~ a:: RCI RCI :> -5 In 30 41 a:: 1&.1

~ o ~ -10 o 1&.1 a:: a:: UJ I.L. 1&.1 a:: z 10 Q ~ Site 6. Looking from sta 5+00 to 9+00 ~ 1&.1 ...J 1&.1

'~IIrt{rtII~fff@tt~ItfItr:r:t::ttl:)))::::n:?:I?W\t{{{t~~/fff{{tft:tt:r

RCI RCI -5 35 35

BONNET CARRE SPILLWAY, LA. Site 6A. Looking from sta 0+00 Site 6A. Looking from sta 0+00 COURSE 2, SITE 6A STATIONS 3+00 4+00 ~+oo 8+00 7+00 8+00 I I , I I I

RCI RCI RCI RCI RCI RCI RCI 28 5 18 50 21 .29 19

RCI 206

BONNET CARRE SPILLWAY, LA. COURSE I, SITE 6

MOBILITY TEST COURSE VIEWS AND PROFILES BONNET CARRE SPILLWAY, LA. SITES 6 AND SA PLATE 4 I 0 +00 I + 00 2 +00 3i 5 -, I I

nr IImll 0 - \tmt~%\\tt

tWi%\m';;;~;;;;Wi#tgmIWillwmWM'm\i};.;)\)(f.

-5 - Site 7, course 1. Looking from Site 7, course 1. Looking from ~ RCI C I lL I5 I42 sta 3+50 to 0+00 sta 9+80 to 0+00 .. ILl U ~ ct :::> -10 If) - ct ILl ~ ~ 0 ~ I5 - 0 ILl ct ct ILl lL ILl ct

~ Z 10 It \ 0 - \ \ ~

Site 7, course 1. Side view of Site 7, course 2. Looking ~ ~" ILl test course from sta 10+00 to from sta 1+80 to 2+20 J , ,, , 11+50 ILl \11' II 5 I-

0 t- . iii!!!!!!!!!!!!!!!!!!!!! BAYOU FIFI

CI RC I -5 "- 8 I 34

Site 7, course 2. Looking from Site 7, course 2. Side view of sta 3+80 to 2+20 test course from sta 4+75 to 4+95 STATIONS 00 4+00 ~+oo 8+00 7+00 8+00 9+00 10+00 11+00 12+00 I I I I I I I I I

RCI RCI RCI RCI RCI RCI RCI \8 6 12 9 17 15 15

COURSE I

RCI RCI RCI RCI 9 II 4 12 MOBILITY TEST COURSE COURSE 2 VI EWS AND PROFILES BEAUREGARD ISLAND, LA. SITE 7, COURSES I AND 2

PLATE 5 0+00 1+00 3+00

RCI RCI 8 13

Site 8. Side view of test Site 8. Side view of test course from sta 0+00 to 7+00 course from sta 7+50 to 9+60 l Ll.. ... I&l o -10 ~ a: ::> In a: I&l ... ~-15 o "I- o I&l a: a: I&l Ll.. W a: Site 8. Looking from sta 9+60 Site 9. Looking from sta z to 12+36 1+65 to 0+00 o ~ ::> I&l ...J W

RCI 9. Looking from 2+30 5 Site sta Site 9. Looking from sta -15 to 0+00 2+75 to 5+00 MINORS CANAL SITE 9 I STATIONS 4+00 ~+OO 6+00 7+00 8+00 SHOO 10+00·

.< • RCI :-:=====-----======.:.BAYOU OU LARGE -=====:--:-====-- 9 -======-~~---===-===----- RCI 15

RCI 9

BAYOU DU LARGE, LA. SITE 8

CI CI 7 5

I 11+00 12+00 13+00 I I I

~~, ~ ... I il .

...... ·:~=:::::f::~tf~~~~;~;:·

RCI RCI 6 4

MOBILITY TEST ·COURSE VIEWS AND PROFILES BAYOU DU LARGE, LA., SITE 8 MINORS CANAL, SITE 9

PLATE 6 I

0+00 1+00 2+00I . 10 I I

~::;i:;'::iiimi!iiimmiiiiiiHrIiiiiiiiIiIi!f!fmii!'!II!f!f!iiiIiiiiiiim:;,m!f!ii!ImmimmmImi!f!iiiiiiiii!iiiiifii'iiiiiHmiiimiii!:IHI Site 10. Looking from sta 0+50 Site 10. Looking from sta l to 2+50 1+20 to 6+50 LL ... -5 UJu MORGAN'S ISL. ~ a: COURSEI.~ :::> I/) a: UJ 10 ~ ~ o t- o UJ a: 5 5 LL UJ a: z o Site lOA. Looking from sta 0+00 Site 11. Looking from sta 0+50 to 7+50 ~ UJ 0 ...J UJ __ -_-_--Blli WAX BAYOU _

Rei RCI -5 5 7

RCI 4 -10

Site 11. Looking from sta 4+80 Site 11. Looking from sta to 10+95 7+50 to 10+95 -15 I STATIONS 4+00 ~+oo 8+00 7+00 8+00 9+00 10+00

RCI436 RCI RCI

CHICKEN ISLAND, LA. COURSE I, SITE II ,

I--_-----=-I..;..,rl+00 2+00 I I

Rei 4

MORGAN'S ISLAND, LA. COURSE 2.SITE lOA

MOBILITY TEST COURSE VIEWS AND PROFILES MORGAN'S ISLAND, LA., SITES 10 AND LOA CHICKEN ISLAND, LA., SITE II

PLATE 7 13 1115 8 I 318 4

1'-.'£YP£RIM£NTALI 2;'XP£R/~£NTAL VCIsO=14 II VCISO=12 'i/ I 40 I, i, I c ILl I- I ILl ...J a. I ~ 0 u 30 I II) ILl f/l 1161 II) I .. « a. I L.. / 0 a: 20 I I ILl lEI ~ J I I Z ~I / I 10 I I ~ 2 I •I j I,-£YP£RIM£NTAL 12:y"(XP£RIM£NTAL ~j • VCI = 6 VCII = 7 o L-_---L_-----.J I I I o 10 20 o 10 20 0 10 20 30 o 10 20 30 40 3- TO 9-IN. RATING CONE INDEX Q. XM759 b. XM759 c. MII6 d. MII6 13,000 LB 16,000 LB 7,600 LB 10,600 LB

LEGEND NOTE: NUMBERS NEAR PLOTTED o VEHICLE DID NOT IMMOBILIZE POINTS ARE TEST NUMBERS. • VEHICLE IMMOBILIZED .. 1964 TESTS ON CH SOIL; VEHICLE IMMOBILIZED RATING CONE INDEX VS NUMBER OF PASSES COMPLETED 5000 ~---~---~---~--~ 0.5 10,000 r I 1.0 PULL =240 OLB (O.U) ~ RCI=23 NOTE: NUMBERS NEAR CURVES DESIGNATE TEST AREA g o bi~;-'Q)--o-+O---o.-A NUMBERS. f o l- "---1 l- l- __ ----' 0 o l- L- L- L- __ ----' 0 I 7500 ~ w d. SITE 8, AREA 3 e. SITE 8, AREA 8 7 J:

"--- lU...- ---'0 .~ 0 l- L- __ 5000 0.5 (5 NOTE: VALUES SHOWN IN FIGURES ARE c. SITE 8, AREA 5 MAXIMUM DRAWBAR PULLS. RCI'S SHOWN ARE THOSE OF THE ~ 3- TO 9-IN. SOIL LAYER . o o • LAST MEASUREMENT BEFORE -\00 -50 0 50 100 TORQUE LIMIT REACHED. SLIP, PERCENT 5000 ~---~---~---,------, 0.5 PULL =3000 LB (0.301 RCI=12 g. SITE 8, AREA 7

o l- "--- L- L- __ ----' 0 -~ -50 0 50 100 SLIP, PERCENT d. SITE 8, AREA 6 DRAWBAR PULL VS SLIP XM759, EMPTY GROSS WEIGHT, 10,000 LB 5000 0.4 10,000 ,------,------,---,------,0.8 NOTE: NUMBERS NEAR CURVES DESIGNATE TEST AREA NUMBERS.

0 0 5000 SITE 7, AREA I a. 7 5000 0.4 PULL =3300 L8 (0.251 8 0 6 I 0 0 b. SITE 7, AREA 2 5000 0.4 10,000 lD ...J ...J' ...J RCI=23 L- ---L -L- ----:'::-- -:-:O :J 0 0 ______ll. c. SITE 8, AREA 3 -50 0 50 100 ce: SLIP, PERCENT < 5000 0.4 lD ,j. FAMILY OF CURVES ~ PULL =3300 L8 (0.25) < a: 0 RCI=I3 0 0 d. SITE 8, AREA 4 5000 0.4

10,000 NOTE: VALUES SHOWN IN fiGURES ARE 0 MAXIMUM DRAWBAR PULLS. RCI=4 RCI'S SHOWN ARE THOSE Of THE 0 0 3- TO 9-IN. SOIL LAYER. e. SITE 8, AREA 5 • LAST MEASUREMENT BEfORE 5000 0.4 5000 TORQUE LIMIT REACHED.

0 RCI=12 ~--_---:' 0 L- __ ---"'.,.--- __ ---"- 0 0 0 -50 0 50 100 -100 -50 0 50 100 -100 SLIP, PERCENT SLIP, PERCENT r. SITE 8, AREA 9 i. SITE 8, AREA 8 DRAWBAR PULL VS SLIP lJ r XM759, 100% RATED PAY LOAD ~ GROSS WEIGHT, 13,000 LB 1"'1 0 10,000 0.6 10,000 r----,------r-----,----,0.6 G S PULLn=5400 L8 (0.34)------. . I NOTE: NUMBERS NEAR f 5000 " 0.3 7500 ---J-- CURVES DESIGNATE I 7 TEST AREA ~ NUMBERS. w ~ 5000~-----,---~------,--~0.3 ""--T------=l 0.3 ~ RCI=6 g. SITE 8, AREA 6 "...J 8 ...J ~ 4 a. [( 0.3 « PULL =2300 L8 (014) 10,000 1Il 1Il 0.6 ~ ...J "OOL: [( .1 ~ o RCI=23 "L,~ ...J i.•,,, ~ 0 0 o .---'------0 a. I~- - -100 -50 0 50 100 c. SITE 8, AREA 3 -~ 5000 0.3 SLIP, PERCENT «'" 5000 0.3 1Il CURVES PULL =2900 L8 (0.18) j. FAMILY or ~ [( 0 I RCI=75 RCI= 13 o o 0 0 h. SITE 8, AREA 7

5000 0.3

10,000 NOTE: VALUES SHOWN IN fiGURES ARE 0.6 MAXIMUM DRAWBAR PULLS. RCI'S SHOWN ARE THOSE Of THE 0 0 1 3- TO II-IN. SOIL LAYER. 5400 (0.34)---...., e. puJ= L8 • LAST MEASUREMENT BEfORE TORQUE LIMIT REACHED. 5000 0.3 5000 0.3 ~ " ~( RCI=12 0 RCI=45 'I 0 0 o o -100 0 50 100 -100 -50 0 50 100 SLIP, PERCENT SL IP, PERCENT T'. SITE 8, AREA 9 i. SITE 8, AREA 8 DRAWBAR PULL VS SLIP XM759, 200% RATED PAY LOAD GROSS WEIGHT, 16,000 LB 5000 5000 10,000 r------,------,------,------, 0.6 ,-,.()("). I I 0.6 II RCI=4 NOTE NUMBERS NEAR CURVES DESIGNATE TEST AREA 1.2 PULL =800 LB ro./o)~ R 11PULL ~4200 LB ~o. n 55)/ NUMBERS. :I n RCI= 12 f -p a I o i o o I o 7500 ---+ 4 ':2 c. SITE 8, AREA 5 e. SITE 8, AREA 6 I w 7 ~ rJ) RCI=23 1.2 RCI=45 rJ) o I17t.p...... I=":::O"il!::i:::::::~~$~~~06~ ...J a ...J o :::> Q. a: 2500 « II) II) ...J ~ 0 OO------'------'------"-----_...JO a: ...J' b . SITE 8. AREA 3 f SITE 8 AREA 8 Cl ...J [ 10,000 10,000 RCI= 13 25 50 75 I 2 I RCI= 12 1.2 a: « SLIP, PERCENT II) I ~ /PU~L = 5200 LB rO.69) « h. FAM ILY OF CURVES a: 5000 Cl 0.6 0.6 ~ I

0 0 o I o SITE 8, AREA 4 o 25 50 75 100 c. SLIP, PERCENT 10,000 CI 75 1.2 g. SITE 8, AREA 9 J r - ~PULL =6300 LB ro. 83) NOTE: VALUES SHOWN IN FIGURES ARE MAXIMUM DRAWBAR PULLS 0 5000 z-r RCI'S SHOWN ARE THOSE OF THE p 0.6 3- TO 9-IN. SOIL LAYER.

o o o 25 50 75 100 SLIP, PERCENT d. SITE 8. AREA 7 DRAWBAR PULL VS SLIP MU6, EMPTY GROSS WEIGHT, 7600 LB 10,000 10,000 ,------,------,------,------, 5000 1--1::::~C(j=f:::::::;o::==t=;:=:1 rPULL=7800 LB (0.74) 0.8 u 0.8 !: 8 f o"'---__ ---" ---L ---'- __ ----J 0 5000 I a. SITE 7, AREA I 0.4 J "j;j 9 ~ en en I I RC 1= 75 PULL =/100 LB rO./Oi" o o @ I ~ I ""'" f. SITE 8, AREA 7 1° -i":::::==--t---=.J=---..d 0.4 ~ ..J :> b. SITE 8, AREA 5 a. NOTE: NUMBERS NEAR CURVES D: r----;;-:::~=r~::::::c;::::::::t=~==;~==:::;J,oDESIGNATE TEST AREA < 5000 .4 [II NUMBERS. 10,000 ~ [II D: /PUL~ ..J = 7800 LB (0.74) 0.8 o IL- __ ---" ---L ---'- __ ----JO .J .J 'V'-- 25 50 75 :> c. SITE 8, AREA 6 ~ SLIP, PERCENT ~10,000 5000 I I 0.4 i. FAMILY OF CURVES <[II VPULL = 7'200 LB (0.68) 0.8

~ r-v -f-- RCI=45 ~ 5000 - o o 0.4 g. SITE 8, AREA 8 fo CI Ie r =23 NOTE: VALUES SHOWN IN FIGURES ARE o o MAXIMUM DRAWBAR PULLS. d SITE 8 AREA 3 RCI'S SHOWN ARE THOSE OF THE 3- TO 9-IN. SOIL LAYER. 10,000 10,000 I I • LAST MEASUREMENT BEFORE 0.8 l,.--PULL= 7100LB (0.67) 0.8 TORQUE LIMIT REACHED. ,,1- " I'--PULL =8000I LB (0.7'5iJ oJ{ IV 5000 f 5000 0.4 0.4 O ~ r:> RCI=13 V FC I=12 o o o o o 25 50 75 o 25 50 75 100 SLIP, PERCENT SLIP, PERCENT DRAWBAR PULL VS SLIP e. SITE 8. AREA 4 h. SITE 8, AREA 9 M116, 100% RATED PAY LOAD GROSS WEIGHT, 10,600 LB 1.0 0.8 _7 0.8 V 7 L ,!...~ - _7 0.4 6 V~ 0 6~4 J s~ ~ 0.2 / 9 4 / 3' SriJ.9~V /' Z :1 o o 25 50 75 100 3- TO 9-IN. RCI a. XM759, 10,000 LB b. XM759, 13,000 LB c. XM759, 16,000 LB w > t; 1.0 « a: 4 ~ I- 0.8 6/ 36 7 04 ~ 7 LEGEND ~ 9,pr0 3 6 El.lPTY 0.8 o lOOQ/a RATED PAY LOAD ( o 200% RATED PAY LOAD V TEST ON CH SOIL, 1964 I 0 6 0.4 r • VEHICLE OPERATINC IN ROLLlNC-WHEEL l.lODE 'l NOTE: NU~BERS NEAR PLOTTED 0.2 I POINTS INDICATE TEST AREA NUMBERS. Is 1>1 o o 25 50 75 100 o 25 50 75 100 3- TO 9-IN. RCI 3- TO 9-IN RCI d. M116, 7,600 LB e. M116, 10,600 LB

MAXIMUM TRACTIVE COEFFICIENT VS SOIL STRENGTH 0.4 ...------...... ------.------...... ------,

0.2 Wl.------I------I------+------\

I Z UJ U IL. .l..- ....L ---J.. ---J U. ol.- oUJ U a. XM759 UJ U z « l ll) lI) UJ a: 0.4 z o oI ::'E ~ 0.2

le. - .. f' --u-

o o 20 40 60 80 3- TO 9-IN. Rei

b. Ml16

LEGEND

/j. EMPTY o 100'70 RATED PAY LOAD D 200'70 RATED PAY LOAD

MOTION RESISTANCE COEFFICIENT VS SOIL STRENGTH

PLATE 15 160 ~------,------~------,

120 1l------1---~----t_------

80 ~------+------t_-----~

I l Z lL l1J ::E

o. XM759. 13,000 LB

80 .------,------,-----~

40 I------U'------.:---+------t------i

40 80 3- TO 9-IN. RCI

b. M116, 10,600 LB

LEGEND

• NOTICEABLE VEHICLE MAN EUVER TEST SIDE SKID TURNING RADIUS VS RATING CONE INDEX

PLATE 16 "'U r 12 12 12 ~ (T1 8 8 8 -Inri L ~~ ~ 4 4 4 ~~~ ~,,~

0 0 o -4 -4 -4 -8 -8 -8 TEST I TEST 2 TEST 3

12 12 12 l- I.. £iITiDl bJ' 8 8 8 u ~ 4 4 4 II: '<..J~:)c::)c::)c::)c::v 0 0 i1l O~~~~~ ~, II: ~ -4 -4 -4 -< :t -8'------L------'------'------' -8 -8 0 10 20 30 40 ~ TEST 4 TEST 5 o TEST 2 li! 12r------, 12 II: bJ l:i 8 8 II: OCDD III 4 J 4

"<..J:~::~~~:v' 0 ~i= 0r~~~~~~,~;;;;~ ~ ~ -4 -4 ~ bJ -8L-----'------'----'------' -8 TEST 3 TEST 6 12r------,

-4

-80~---,-!;------=':=----~-----,l40.-80~--+-----,J=----~----,J 10 20 30 10 20 30 40 DISTANCE, fT TEST 7 TEST 8 WATER-EXIT TEST PROFILES BAYOU DU LARGE, LA., SITE 8 100 o ~ t- _ ~ 1--,~ ~

...... '" '" l' r",....~~ 80 20 I- Z " , \ \ I W NOTE: TEMPERATE - UNITED STATES. U " , W 0:: f\ 1\ --l W TROPICAL - PUERTO RICO, PANAMA,- m Il. ", 1', HAWAII, THAILAND, COSTA RICA. « ~ ~ , '"" i LL w 60 ,\ I" 1\ 40 LL U « Z 0:: W "~ I- 0:: (J) 0:: ~ « ::J w U 0:: U "\ '\ « 0 ~ I LL LL 40 1\" 60 0 0 I- >- '" Z U ~ ~ W Z '-, U W 1\.' 0:: ::J , W 0 '\ Il. W 0:: "," ~...... LL " ' .... 20 80 ...... ~ ~ ~ ...... ~1''-.., I' ]'.. ~ 1'- - -- ...... -- t-- r----.,:1--~ _"'"-""::-- r--- t-- o 100 300 200 100 90 80 70 60 50 40 30 20 10 STRENGTH IN RATING CONE INDEX (USED WITH FREQUENCY OF OCCURRENCE IN PERCENT) OR VEHICLE CONE INDEX (USED WITH PERCENT OF AREAS TRAFFiCABLE) LEGEND CUMULATIVE FREQUENCY OF RATING CONE INDEXES TEMPERATE CLIMATE _ WET-SEASON CONDITION, 767 SITES IN HUMID-TEMPERATE AND TEMPERATE CLIMATE _ HIGH-MOISTURE CONDITION, 319 SITES HUMID-TROPICAL CLIMATES TROPICAL CLIMATE _ WET-SEASON CONDITION, 284 SITES TROPICAL CLIMATE _ HIGH-MOISTURE CONDITION, 133 SITES FINE-GRAINED SOIL, 6- TO 12-IN. LAYER . ~ : ; } ;> !! ~z.. ~\ 20 ,'2: o' --;r- - ) 0 L A 0 S BUR j'-' lid ..:i CIIl.I' 01'

r 0 I't K II't

I~ I~

BAY

'2'

01'

C Ill. I' 01' S I A II BEI'tCAl.

10' '0'

cl I -

c 8'-

...... ("(" .... MALAYA DISTRIBUTION OF SCALE IN MILES SOIL STRENGTH UNDER 50 0 50 100 -=-=- WETTEST CONDITIONS THAILAND · PLATE 19 COMPOSITE AREA 1 AREA 2 AREA 3 AREA 4 AREA 5 AREA 6 (AREAS 1-6)

80 I--t--+-+--+--J

60 f Z UJ U ll: [lUJ 40

SOIL STRENGTH MAPPING CLASSES

CLASS RANG E CI 1 0-15 AREAL DISTRIBUTION OF SOIL 2 16-25 \J r 3 26-60 SURFACE STRENGTH CLASS 4 61-100 ~ 5 > 100 RANGES IN MEKONG DELTA fTI 6- TO 12-IN. CONE INDEX oI\.l 1.0

,-M116

0.8 /

( vXM759~ 0.6 j v 0.4 7 :h~V 0.2 -

I- Z J l1J 0 U lJ.. o. VEHICLES, EMPTY lJ.. l1J 0 U l1J > I- U 1.0 c( lr I-

0.8 ,.-- M1l6

0.6 / 7 t--XM759 ~ 0.4 .£ / ~ 0.2 - /

o I o 25 50 75 100 3- TO 9-IN. Rei

b. VEHICLES, 100"10 RATED PAY LOAD

COMPARISON OF TRACTIVE COEFFICIENT-SOIL STRENGTH RELATIONS

PLATE 21 0.4

~ 0.3 \ z W U LL LL W 0 U W U t'... Z 0.2

o o 10 20 30 40 50 60 70 80 3- TO 9-IN. Rei

COMPARISON OF MOTION RESISTANCE COEFFICIENT VS SOIL STRENGTH 160

140

120

~XM759

100

l- LL en :J 0 « 80 lr Cl -Z Z lr :J I-

40 \

~K:16 ~--- 20 -- ..... ------I- Z W :::;: W «> o a. o 20 40 60 80 100 120 3- TO 9-IN. Rei

COM PARISON OF TURNING RADIUS VS SOIL STRENGTH 1000/0 RATED PAY LOAD

PLATE 23 97.9% 97.9%

85.J%

74.3% 74.3%

12 11 10 9 B 7 6 5 4 3 2

VEHICLE SPEED, MPH

LEGEND

XM759 (BASED ON 47 TERRAIN TYPES ATTEMPTED)

Ml16 (BASED ON 35 TERRAIN TYPES ATTEMPTED)

PERCENTAGE OF TERRAIN TYPES NEGOTIATED AT VARIOUS SPEEDS

PLATE 24 APPENDIX A: DETERMINATION OF VEHICLE CONE INDEXES FOR TRACKED VEHICLES

Fine-Grained Soils

1. The vehicle cone index (VCI) is the minimum soil strength, in terms of rating cone index, that will permit a vehicle to complete 50 passes. It is based on the mobility index (MI) of the vehicle. Computa tions of the MI's for the XM759 (as a tracked vehicle) and the Ml16 are described in the following paragraphs. Mobility index 2. The MI is a dimensionless number obtained by applying vehicle characteristics to the following formula:

MI = (contact pressure factor X weight factor + bogie factor track factor X grouser factor

- clearance factor) X engine factor X transmission factor where

contact gross weight, lb pressure :=: area of tracks in contact with ground, sq in. factor

<50,000 lb :=: 1.0 weight = 50,000 to 69,999 lb 1.2 factor 70,000 to 99,999 lb :=: 1.4 100,000 lb or greater :=: 1.8

track = track width, in. factor 100

grouser _ <1.5 in. high = 1.0 factor - 1.5 in. high or greater 1.1

bogie gross weight, lb + 10 factor total number of bogies in) (area of one. track) ( contact with ground X shoe, sq In.

clear ance :=: clearance, in. factor 10

Al engine _ ~ 10 hp per ton of vehicle wt = 1.0 factor - < 10 hp per ton of vehicle wt = 1.05

trans hydraulic = 1.00 mission = mechanical 1.05 factor =

3. XM759. In determining the MI for the XM759 it was assumed that its track length is the distance between centers of idler and drive sprock ets and that its track width is the nominal width of the tires. It was also assumed that the tires act as grousers and bogies, and that the area of one track shoe is the area of one tire determined from the tire length and width as given in the tire size. With these assumptions, MI' s for the XM759 at 10,000 lb (empty), 13,000 lb (1000/0 rated pay load), and 16,000 lb (2000/0 rated pay load) are computed as follows:

10,000, 13,000, or 16,000 1 0 10,000, 13,000, or 16,000 ) _ 187 x 21 x 2 x • 10 33 MI - 21 + ( 100 x 1.1 12 x 24 x 21 - 10

x 1.0 x 1.0 = 2.4 at 10,000 lb, 4.1 at 13,000 l~ and 5.8 at 16,000 lb

4. Ml16. For the Ml16 at 7600 lb (empty) and 10,600 lb (1000/0 rated pay load), MI's are computed as follows:

7600 or 10,600 X 1 0 7600 or 10,000 98 x 20 x 2 . 10 5 MI = 20 + - lio ) X l.0 X l.0 ( 100 x 1.1 10 x 20 x 4

= 9.1 at 7600 lb and 13.3 at 10,600 lb

Vehicle cone index 5. The VCI' s are obtained from table Al which converts MI to VCl. VCI's for the two vehicles and loads tested are as follows:

A2 Vehicle VCI* VCI Designation Test Weight, Ib 1 50 XM759 10,000 5 13 XM759 13,000 7 18 XM759 16,000 8 21 Ml16 7,600 10 25 Ml16 10,600 12 29

* 4~ of VCI . 50

Organic Soils

6. The vcr is the minimum soil strength, in terms of cone index (CI), that will permit a vehicle to complete 50 passes. The VCI for 50 organic soils containing a predominant amount of peaty material is obtained from the following equation

W 14 + 1.5 P where W= vehicle test weight, Ib P = perimeter of track area in contact with firm ground surface, in. The VCI determined in this manner is considered to be a dimensionless 50 number. 7. The VCI was computed f'or the XM759 and Ml16 using the equation 50 above. In determining the perimeter of the track ground contact area for the XM759, it was assumed that its track length is the distance between centers of idler and drive sprockets and that its track width is the normal width of the tires. This gave a track width of 21 in. and a track length of 187 in., and a total track perimeter of 832 in. For the Ml16 a track width of 20 in. and a track length of 98 in., and a total track perimeter of 472 in. was used in the computation. With these assumptions, VCI 50 computations for the XM759 and Ml16 for the various test weights are as follows.

A3 1~3~00 XM759 VCI = 14 + 1.5 (10,000 or or 16,000) 32 at 10,000 lb, 50

37 at 13,000 lb, and 43 at 16,000 lb

7600 or 10,000 ) Ml16 VCI = 14 + 1.5 472 38 at 7600 lb and 46 at 50 (

10,000 lb

A4 Table Al

Mobility Index Versus Vehicle Cone Index

MI VCI MI VCI MI VCI MI VCI MI VCI ------0 3.0 31 39.2 67 55.6 103 72.0 139 88.3 0.25 5.5 32 39·7 68 56.1 104 72.4 140 88.8 0.50 7.0 33 40.1 69 56.5 105 72·9 141 89.2 0.75 8.3 34 40.6 70 57.0 106 73.3 142 89.7 1.00 9·0 35 41.0 71 57.4 107 73.8 143 90.1 1.50 10.8 36 41.5 72 57·9 108 74.2 144 90.6 2.00 12.5 37 42.0 73 58.3 109 74.7 145 91.0 2.50 13.8 38 42.4 74 58.8 110 75.1 146 91.5 3 15.1 39 42.9 75 59·2 III 75.6 147 91.9 4 17.5 40* 43.4* 76 59·7 112 76.0 148 92.4 5 19·7 41 43.8 77 60.2 113 76.5 149 92.8 6 21.5 42 44.3 78 60.6 114 77.0 150 93.3 7 23.0 43 44.7 79 61.1 115 77.4 151 93.8 8 24.2 44 45.2 80 61.5 116 77·9 152 94.2 9 25.3 45 45.6 81 62.0 117 78.3 153 94.7 10 26.4 46 46.1 82 62.4 118 78.8 154 95.1 11 27.3 47 46.5 83 62.9 119 79·2 155 95. 6 12 28.1 48 47.0 84 63.3 120 79.7 156 96.0 13 28.9 49 47.4 85 63.8 121 80.1 157 96.5 14 29. 6 50 47.9 86 64.2 122 80.6 158 96.9 15 30.4 51 48.4 87 64.7 123 81.0 159 97.4 16 31.0 52 48.8 88 65.2 124 81.5 160 97.8 17 31.7 53 49.3 89 65.6 125 82.0 161 98.3 18 32.3 54 49.7 90 66.1 126 82.4 162 98.7 19 32.9 55 50.2 91 66.5 127 82.8 163 99·2 20 33.5 56 50.6 92 67.0 128 83.3 164 99.6 21 34.1 57 51.1 93 67.4 129 83.8 165 100.1 22 34.6 58 51.5 94 67.9 130 84.2 166 100.6 23 35.2 59 52.0 95 68.3 131 84.7 167 101.0 24 35.8 60 52.4 96 68.8 132 85.1 168 101.5 25 36.3 61 52.9 97 69.2 133 85.6 169 101·9 26 36.8 62 53.3 98 69.7 134 86.0 170 102.4 27 37.3 63 53.8 99 70.1 135 86.5 171 102.8 28 37.8 64 54.2 100 70.6 136 86.9 172 103.3 29 38.3 65 54.7 101 71.1 137 87.4 173 103.7 30 38.7 66 55.2 102 71.5 138 87.8 174 104.2

* For MI's above approximately 40, VCI obtained from equation VCI = 25.2 + 0.454 X MI. APPENDIX B: EFFECTS OF SOFT SOIL BUOYANCY ON VEHICLE CONE INDEX DETERMINATION

Introduction

L A comparison of the XM759 computed and experimentally determined VCI for fine-grained soils has shown that a large difference occurred 50 between them. The XM759 was able to complete 50 passes on all soil strengths tested including extremely soft, viscous soils, whereas the computed VCI indicated that the XM759 (with 100% pay load) should not 50 travel on an RCI of less than 18. Test observations revealed that the Terra tires and sponsons provided immediate buoyancy when immersed in soft, viscous soils, thereby reducing the vehicle weight by the weight of the soil displaced (see fig. Bl). To achieve a closer agreement between

Fig. Bl. Example of effect of buoyancy. XM759 operating at Appomattox, Va., site 1, near sta 4+00, of the mobility test course; RCI 2 experimental and computed VCI, the effects of soft soil buoyancy for soils of 7 RCI and less were examined.

Bl Volume and Weight Computations

Vehicle component volumes 2. The volume computations for the vehicle components that provide vehicle flotation are as follows:

Terra tires

~D2 2 " rc X 24 21 Volume per tire T Xw = 4 x

9500 1728 = 5. 5 cu ft

where

2 rcD 4 = the area of a cylinder (D is in inches)

w = width of tire, inches

Sponson

Volume width (26 in.) x length (166 in.) X height in inches (depending upon depth to which sponson is immersed)

4320 x h 1728 cu ft

Hull

Volume width (56 in.) x length (210 in.) x height in inches (depending upon depth to which hull is immersed)

= 1750 x h cu ft 1728

The equations above were used to compute displaced volumes for the vehicle's

B2 flotation components for assumed sinkages 12 in. and greater. The results are shown below. Sinkage is plotted against total volume displaced in plate Bl.

Volume Displacement, cu ft Sinkage Spon- in. --Tires son Hull Total 12 38 0 0 38 18 62 0 0 62 24 77 0 0 77 28 81 20 0 101 30 83 30 0 113 32 85 40 0 125 34 87 50 0 137 36 89 60 0 149 38 91 70 15 176 40 94 80 27 201 42 96 90 42 228 44 99 100 54 253

Effect of buoyancy on vehicle weight 3. The effect of buoyancy on vehicle weight when operating in water and soft soil is considered separately in the following paragraphs. 4. Water. In water the XM759 floats at 1000/0 and 2000/0 rated pay load when its sinkage is 40 and 44 in., respectively. The decreases in weight provided by the tires, sponsons, and hull when floating in water with 1000/0 and 2000/0 rated pay loads are as follows:

Tires

1000/0 pay load 5.5 cu ft/tire X 17 tires X 62.4 pcf 5800 lb

2000/0 pay load 5.5 cu ft/tire X 18 tires X 62.4 pcf 6200 lb

Sponson

M a pay load 4320 X 16 2 6 4 10VIC 1728 X sponsons X 2. pcf 5000 lb

M 20v~a pay load 43201728X 20 X 2 sponsons X 62. 4 pef = 6200 lb

B3 Hull

100% pay load 11'i~~8X 4 X 62.4 pcf = 1700 lb

200% pay load 11'i~~8X 8 X 62.4 pcf = 3400 lb

Total displacement

100% pay load = 12,500 (13,000)* lb 200% pay load = 15,800 (16,060)* lb

5. Soil. Computations 'were made to determine the buoyancy for a range of wet soil densities and vehicle sinkages. The buoyancy in water is also included for comparison. The results of these computations are shown below, and a curve of buoyancy versus sinkage for several wet soil densities is shown in plate B2.

Vehicle Weight Lost by Buoyancy, lb Water pcf Wet Soil Density, pcf Sinkage, in. 62.4 70 80 90 12 2,376 2,660 3,040 3,420 18· 3,869 4,340 4,960 5,580 24 4,805 5,390 6,160 6,930 28 6,302 7,070 8,080 9,090 30 7,051 7,910 9,040 10,170 32 7,800 8,750 10,000 11,250 34 8,549 9,590 10,960 12,330 36 9,298 10,430 11,920 13,410 38 10,982 12,320 14,080 15,840 40 12,542 14,070 16,080 42 14,102 15,820 44 15,787

* Vehicle test weight.

B4 Buoyancy Effects on VCI Determination

6. Several tests (Nos. 9, 19, and 13, see main text) were con ducted during this study on flooded soil of less than 7 RCI in which the buoyancy of both water and soft soil affected the performance of the vehicle by reducing its effective weight (gross vehicle weight minus buoyancy). The test weights and sinkages measured after 50 passes are as follows:

Vehicle Sinkage After 50 Wet Soil Test Test wt Passes, in. Density No. lb Water Soil --Total pcf* 9 13,000 16.0 17.0 33.0 85.2 19 13,000 14.4 23.6 38.0 73·3 13 16,000 15.6 24.4 40.0 73.3

* Average of all depths sampled.

7. From the information above, the volume of either water or soil displaced by the vehicle and the reductions in vehicle weight buoyancy were determined from plates Bl and B2. The results are as follows:

Volume Displaced Vehicle Weight lost by Test cu ft Buoyancy, lb No. Water Soil Water Soil Total 9 73 58 4550 4940 9,490 19 98 77 6110 5650 11,760 13 123 78 7660 5710 13,370

8. From the above -listed weight reductions, the effective weight of the vehicle becomes:

Test Total Vehicle 'Weight Effective No. Weight, lb Reduction, lb Weight, lb 9 13,000 9,490 3510 19 13,000 11,760 1240 13 16,000 13,370 2630

9. By taking into account the effect of buoyancy on vehicle weight, computed VCI's can be obtained that more nearly agree with experimental

B5 VCI's. Reduction of effective weight may explain why the XM759 completed 50 passes (with difficulty) on an RCI of 2 (paragraph 41, main text) since a computation following the instructions set forth in this appendix would show that when effective weight is less than 5700 Ib, VCI becomes zero.

B6 10 \ 15 ~TIRE5

25 i -\- w'" ~ « \ \TIRES AND SPONSONS li:: Z iii 30

35 \-, TIRES, SPONSONS, AND HULL I ~ 40 ~

45 o 50 100 150 200 250 VOLU~E DISPLACE~ENT, CU FT

SINKAGE VS VOLUME DISPLACEMENT

PLATE 81 10 ,----...... ,."''""----.-----,-----,------,------r------,------,

1.5 t------t--~~--i<~~--+----+------1f__-----+----+----_____1

20 t------t------t\---\-----'\---I\:----+------1f__-----+----+------I

. 2 ~ t------t-----+--~----"'

FLOATING DEPTH 3llN.;----....---''k---~---t-----''---+------1 35 f------t-----+--AT EMPTY =

FLOATING DEPTH AT I100% PAY LOAD =40 IN. 40 t------t-----+----+----+------If--.=----+-...,,""-:----~...,___---_____=1

4~ '-- --'- ---'- ...l- .L. --lL- ---'- .....L ----l

o 2 4 6 8 10 12 14 16 WEIGHT LOST BY BUOYANCY, 1000 LB

SINKAGE VS WEIGHT LOST BY BUOYANCY

PLATE 62 APPE:NDIX C: COMPARISON OF TERRAIN TYPES

Background

Purpose and scope 1. The purpose of this appendix is to present briefly the results of a terrain evaluation study conducted to identify terrain types in several sections of South Vietnam (fig. Cl) and locate similar areas in the Mississippi River Delta (fig. C2) for vehicle test purposes. Readily available information (maps and reports) was used in preparing this study. It was hypothesized that by testing vehicles in accessible areas similar to remote areas meaningful decisions could be made as to the expected performance of the vehicle in a remote environment. Definitions 2. Terms used in terrain factor mapping are defined below. Terrain type. An area throughout which a specific assemblage of factor values occur. Vegetation. Vegetation includes all attributes of plant structure either as individual plants or as complexes or associations of plants. Stem diameter and stem spacing were used for this study. Hydrologic-vegetation association. An association of vegetation with stems less than 1 in. in diameter usually found associated with surface water. Surface geometry. Surface geometry is the three-dimensional con figuration of a ground surface on which a ground contact vehicle operates. Surface composition. Surface composition is concerned with the engineering properties of the earth's surface (chiefly soils, in terms of soil mass strength). Terrain factor. A specific attribute of the terrain (which can be defined either quantitatively or in semiquantitative or qualitative fashion) that forms an exclusive category. Factor class. A specific category within a terrain factor defined as having a specific range of size, configuration, strength, -an~or other property.

Cl 0 12 0 ~ 12 -N- ~

0 10 0 MEKONG 10 , ~ GULF e.. ~ UJe.. o OF CA MAU

SIAM

LEGEND

""":r FRENCH COLONIAL BOUNDARIES INTERNATIONAL BOUNDARY APPROXIMATE GEOGRAPHIC LIMIT OF MEKONG DELTA IN SOUTH VIETNAM

25 o 25

25 0 8 0 8

1060 1080

Fig. Cl. Study areas in Mekong Delta, South Vietnam

C2 Fig. C2. Study areas in Louisiana Vertical obstacle. Irregularities on the ground surface that force the vehicle to move in a vertical plane (i.e. up and down). Step height. The vertical distance between the bottom and the top of the obstacle. Terrain approach angle. The angle formed by the contact plane of the vehicle and the slope of the obstacle. Obstacle spacing. The minimum distance between vertical obstacles.

Terrain Factors

3. Terrain factors that affect ground mobility have been placed into four groups or families: (a) vegetation, (b) surface geometry, (c) surface composition, and (d) hydrologic geometry. A hydrologic vegetation association was utilized in this study where vegetation stems were less than 1 in. in diameter. Factor classes mapped 4. The factors mapped in both delta regions and ranges of values (factor classes) used to quantitatively describe each factor are dis cussed in the following paragraphs. 5. Vegetation. Two aspects of vegetation where the stem diameters are greater than 1 in. that were considered are: (a) stem diameter and (b) stem spacing. Where stems were less than 1 in. in diameter, the hydrologic-vegetation association was described by the water depth and plant characteristics. a. Vegetation mapping classes are tabulated below:

Class Range Factor 1 2 _3_ 4 stem diameter, in. >1 >2.5 >5.5 >8.5

Class Range Factor a b c d ---- Stem spacing, ft 0-8 8.1-15 15.1-25 >25

b. Hydrologic-vegetation associations are as follows:

",------(1) Water depth classes are Class 1, less than 3 ft Class 2, 3 to 4.5 ft Class 3, greater than 4.5 ft (2) Plants are described by a number-letter-number system as follows: 1 Water lily (floating flat leaves rooted) 2 Water hyacinth (floating masses 1 to 2 ft above the water to 1 to 2 ft below the water) 3 Graminoids (grasses, sedges, rushes, cattails) a Tall (>3 ft in height) (1) . Non-tussock (2) Tussock b Short «3 ftr in height) (1) Non-tussock (2) Tussock

6. Surface geometry. The surface geometry parameters selected to describe the surface features are: (a) step height, (b) approach angle, (c) obstacle spacing, and (d) slope. The class ranges are shown below.

Class Range Factor 1 2 3 4 5

Step height, in. <12 12-20 >20 Approach angle, deg <135 135-150 >150 Obstacle spacing, ft <50 50-150 >150 Slope, deg <1.5 1.5-4. 5 4.6-10 10.1-17 >17

Note: Surface geometry types, i.e. 1331, indicate factors of step height, approach angle, spacing, and slope and are always designated in that order. The class ranges for each factor are listed under the map unit.

7. Surface composition. Soil conditions were evaluated in terms of soil mass strength in ranges of CI values for the 6- to 12-in. layer. These mapping classes are shown on the following page.

C5 Classes Range of CI 1 0-15 2 16-25 3 26-60 4 61-100 5 >100

8. Hydrologic geometry. In this report, hydrologic geometry is concerned only with bodies of water 3 ft deep or more. Bodies of water less than 3 ft deep are described by surface geometry mapping classes. Hydrologic geometry factors that were mapped include: (a) contact approach angle, (b) water depth, and (c) channel width. Class ranges for these factors are shown below.

Class Range Factor 1 2 3 Contact approach angle, deg* <150 150-165 >165 Water depth, ft q 3-4.5 >4.5 Channel width, ft ~o 20-60 ~O

* Contact approach is defined under two conditions: (a) where the water depth is between 3.0 and 4.5 ft, and (b) where the water depth is greater than 4.5 ft. The contact approach angle under condition (a) is the angle between the bed and bank of the water body; under condition (b) it is the angle formed by a line parallel to and 4.5 ft below the water sur face and the bank of the water body.

Terrain type map 9. To portray the total terrain conditions, all the factor maps (excluding hydrologic geometry) were synthesized into a single map, referred to as a terrain type map. The procedure is to overlay each factor map (excluding hydrologic geometry) whereby each different factor combination is outlined, identified, and tabulated. Each terrain type is identified by an array of numbers. The first group describes vege tation. If two numbers or a number and number-Ietter-number combination are used, vegetation is described as a hydrologic-vegetation association.

c6 If four numbers or number-letter combinations are used, the vegetation is described in terms of stem size and spacing. The next four numbers de scribe surface geometry and the factors include step height, approach angle, obstacle spacing, and slope. The last number describes surface composition in terms of cone index. For example, in table Cl the first terrain type in the first column is symbolized as 1,3b(2) 1,2,2,1 3. The first group describes the vegetation as a hydrologic-vegetation (HV) association (number and number-letter-number combination), the next four numbers describe surface geometry (SG), and the last number describes the surface composition (SC). The factors and classes designated by these numbers are as follows:

Factor Family Factor Class Description

Hydrologic-Vegetation Association

HV Water depth 1 Less than 3 ft Plant description 3b Graminoids (grasses, sedges, rushes, and cattails). Short «3 ft in height) Plant description Tussocks

Surface Geometry

SG Step height 1 Less than 12 in. Approach angle 2 135-150 deg Spacing 2 50-150 ft Slope 1 Less than 1.5 deg

Surface Composition

SC Cone index (6- to 3 26-60 12-in. layer)

10. For comparison purposes this system was used to identify 114 ter rain types in the Mekong Delta, 30 terrain types in the Mississippi Delta, and 44 terrain types along the mobility test courses. It is to be noted that the above system identified surface composition only in terms of CI in the 6- to 12-in. layer. In the evaluation of actual performance of the XM759 the system used to identify surface composition along the test courses incorporated soil type and rating cone index for the critical layer. For this reason the numbers of terrain types identified by each system differ somewhat. C7 Development of Analog Criterion

11. The determination of analogous terrain types in two noncontiguous areas was made by comparing the terrain type identified in one area with that of another area. The criterion used in determining the degree of analogy was based upon the number of factor classes used to describe a terrain type that were in agreement. The relation of factor classes to the degree of analogy used is given in the following tabulation.

Number of Factor Classes in Agreement (6 total) (7 total) (8 total) (9 total) Degree of Analogy 6 7 7-8 8-9 Analogous 5 5-6 5-6 6-7 Highly analogous 3-4 3-4 3-4 4-5 Moderately analogous 1-2 1-2 1-2 1-3 Slightly analogous 000 0 Not analogous

Comparison of Mekong Delta and Mississippi River Delta Terrain Types

12. Table Cl is a comparison of the Mekong Delta terrain types with the closest association identified in the Mississippi Delta and the de gree of analogy between them. Of the 30 terrain types identified in the Mississippi Delta, 19 are analogous to one or more terrain types iden tified in the Mekong Delta, 9 are highly analogous, and 2 are moderately analogous.

Comparison of Mekong Delta and Mobility Test Course Terrain Types

13. Table C2 is a comparison of the mobility test course and Mekong Delta terrain types and the degree of analogy assigned. Forty-four ter rain types were identified along the mobility test courses. Of these 44 types, 16 are highly analogous to one or more terrain types identified in the Mekong Delta, 14 are analogous, 12 are moderately analogous, and 2 are slightly analogous.

c8 Table Cl

Comparison of Mekong Delta and Mississippi Delta Terrain Types

Terrain Types Mekong Delta Mississippi Delta V* or IN SG SC Vor IN SG SC Degree of Analogy

1,3b(2) !,2,2,! Highly analogous i,3b(2) !';i,2,! Analogous i,3b(2) !,2,2,! 1,3b,2 1,3,3,1 2 Analogous i,3b(2) !.,2,2,! Analogous !:,3b (2) 3,2,2,! 11 Highly analogous 1,3b(2) !,2,2,! Highly analogous Analogous 1,3b(2) !,2,2,! 1,3b,2 1,3,3,1 4 1,3b(2) !,2,2,! Analogous ];,3b@ !,2,2,! il Analogous 1,3b(2) !,1,2,! Highly analogous 1,3b(2) Highly analogous !,2,2,! 1,3b,2 1,3,3,1 5 1,3b(2) !,2,2,! Analogous ];,3b(~) !,2,2,! il Analogous 1,3b(2) 3,1,!,! Highly analogous Highly analogous 1,3b(2) 3,1,!,! 1,3b,2 2,3,1,1 4 1,3b(2) 3,3,1,1 Highly analogous ];,3b@ 3,]:,2,]; H Highly analogous 1,3b(2) ~,2,2,l Highly analogous ~,2,1,! Analogous 1,3b(2) 1,3b,2 2,3,3,1 1 1,3b(2) ~,2,1,l Highly analogous ];,3b@ 3,1,1,l E Highly analogous 1,3b(2) ~,2,2,l 3 Highly analogous 1,3b(2) 2,2,2,1 4 Highly analogous 1,3b(2) ~,2,1,]; "3 Highly analogous 1,3b(2) ~,2,1,l 4 Highly analogous 1,3b(2) ~,1,1,! "3 Analogous 1,3b(2) ~,1,1,! 4 1,3b,2 2,3,3,1 4 Analogous 1,3b(2) 3,1,2,1 4 Highly analogous 1,3b(2) 3,1,1,]; 4 Highly analogous 1,3b(2) 3,1,1,3 4 Highly analogous 1,3b(2) 3,2,2,! "3 Moderately analogous 1,3b(2) 3,2,2,1 4 Highly analogous ];,3b@ 3,1,2,]; 4 Highly analogous 1,3b(2) ~,2,2,! Highly analogous 1,3b(2) ~,2,1,! Analogous 1,3b,2 2,3,3,1 1,3b(2) ~,1,1,! 5 Analogous ];,3b@ 3,1,2,3 II Highly analogous la,2a,3b,4d Analogous !,l,l,l la,2a,3b,4d 1,3,3,1 1 la,2a,3b,4d 3,2,2,! I} Highly analogous la,2a,3b,4d !,1,2,! Analogous la,2a,3b,4d !,1,2,! Analogous la,2a,3b,4d 3,2,2,1 la,2a,3b,4d 1,3,3,1 3 Moderately analogous la,2a,3b,4ci 3,1,1,I Highly analogous la,2a,3b,4d 3,1,2,! I] Highly analogous la,2a,3b,4d 1,1,2,1 Highly analogous la,2a,3b,4d 1,2,2,5 Highly analogous la,2a,3b,4d 1,1,2,! Highly analogous la,2a,3b,4d !,1,2,! la,2a,3b,4d 1,3,3,1 5 Analogous la,2a,3b,4d !,1,2,! Analogous la,2a,3b,4d 3'2,2,3 ;~ Highly analogous la,2b,3b,1ib !,1,1,! Highly analogous la,2a,3b,4d 1,2'2'! 4 la,2a,3b,4d 2,1,3,1 5 Highly analogous la,2a,3c,4d !,1,2,! 1 la,2a,3c,4d 1,3,3,1 1 Analogous la,2a,3c,4d Analogous !,1,1,! la,2a,3c,4d 1,3,3,1 2 la,2a,3c,4d 3,1,1,! n Highly analogous ( Continued)

Note: The underlined factor classes shown in the Mekong Delta terrain type column indicate that these factor classes also occurred as a part of the Mississippi Delta terrain type to which one comparison was being made. Under the columns headed V or IN a number and number-letter-number combination, i.e. 1,3a(1), indicate a hydrologic-vegetation association. A four number-letter combination, i.e. la,2a,3b,4d, indicates vegetation. *V = vegetation IN = hydrologic-vegetation association SG surface geometry SC = surface composition Table Cl (Concluded)

Terrain Ty}les Mekong Delta Mississi~D",lta V or HV SG SC V or HV SG SC Degree of Analogy la,2a,3c,4d .!:,},},.!: Analogous la,2a,3c,4ci 3,1,1,3 la,2a,3c,4d 1,3,3,1 3 Moderately analogous la,2a,3c,4ci 3,},2,.!: j} Highly analogous la,2a,3c,4d Analogous .!:,2,},.!: la,2a,3c,4d 1,3,3,1 4 la,2a,3c,4ci .!:,},},.!: ~1 Analogous la,2a,3c ,4d .!:,2,},.!: Analogous la,2a,3c,4ci 1,3,3,1 Analogous la,2a,3c,4d 1,3,3,1 5 la,2a,3c,4ci :L},},1i Analogous la,2a,3c,4ci .!:,},},5 Il Analogous la,2a,3c,4d ~,2,},.!: Analogous la,2a,3c,4d 2,1,3,1 la,2a,3c,4ci 3,.!:,2,.!: ~1 3 Highly analogous la,2a,3c,4d ~,2,2,.!: 4 la,2a,3c,4d 2,1,3,1 4 Highly analogous la,2a,3b,4d ~,2,2,.!: Highly analogous la,2a,3c ,4d 2,1,3,1 5 la,2a,3c,4ci ~,2,},2 ~1 Highly analogous la,2a,3b,4d ~,2,2,.!: 1 la,2a,3c,4d 2,3,3,1 1 Highly analogous la,2b,3b,4b 3,~,2,2 2: la,2a,3b ,4d 2,2,3,1 5 Moderately analogous la,2a,3d,4d 3,~,2,2 2: la,2a,3c,4d 2,2,3,1 5 Highly analogous la,2a,3c,4d 3,},2,3 2: la,2a,3c,4d 2,3,3,1 5 Highly analogous la,2b,3c,4d .!:,2,},.!: 5 Highly analogous la,2b,3c,4ci .!:,},l,.!: 5 Highly analogous la,2b,3c,4ci .!:,},2,.!: 1 Highly analogous la,2b,3c,4ci .!:,},2,.!: 3 Highly analogous la,2b,3c,4ci .!:,},},.!: 1 Analogous la,2b,3c,4ci .!:,},},.!: 3 Analogous la,2b,3c,4ci .!:,},},.!: 4 la,2b,3c,4d 1,3,3,1 4 Analogous la,2b,3c,4ci .!:,},},.!: "5 Analogous la,2b,3c,4ci .!:,},},5 5 Highly analogous la,2b,3c,4ci 2,2,},.!: 4 Highly analogous la,2b,3c,4ci 3,1,1,.!: 5 Moderately analogous la,2b,3c,4ci 3,2,},.!: 4 Highly analogous la,2b,3c,4ci 3,},2,3 "5 Moderately analogous la,2b,3c,4d 1,3,3,1 Highly analogous la,2b,3c,4ci 1,3,},1i Highly analogous la,2b,3c,4ci ~,2,2,.!: Highly analogous la,2b,3c,4ci ~,2,2,.!: la,2b,3c,4d 2,1,3,1 2 Highly analogous la,2b,3c,4ci ~,2,2,.!: Highly analogous la,2b,3c,4ci 3,.!:,},.!: Highly analogous la,2b,3c,4ci 3,2,2,.!: 11 Moderately analogous lb,2c,3d,4d ~,2,2,.!: Moderately analogous lb ,2c,3d,1id ~,2,},.!: la,2d,3d,4d 2,1,3,1 3 Highly analogous lb,2c,3d,4ci ~,3,},.!: jl Highly analogous lb,2c,3d,4d ~,2,2,.!: 4 la,2d,3d,4d 2,1,3,1 5 Moderately analogous lb,2c,3c,4d .!:,},},.!: Analogous Analogous lb,2c,3c,4ci .!:,},},.!: lb,2c,3c,4d 1,3,3,1 1 lb,2c,3c,1id .!:,},},.!: Analogous lb,2c,3d,4ci .!:,},},.!: tl Analogous lb,2b,3b,4b .!:,},},.!: 2: Highly analogous lb,2c,3d,4d .!:,2,2,.!: 5 Highly analogous lb ,2c,3d,"lid .!:,},2,.!: "3 Highly analogous lb ,2c, 3d,"lid .!:,},2,.!: 4 Highly analogous lb,2c,3d,4ci .!:,},2,.!: 5 Highly analogous lb,2c,3d,"lid .!:,},},.!: "3 lb,2c,3c,4d 1,3,3,1 5 Highly analogous lb,2c,3d,"lid .!:,},},.!: 4 Highly analogous lb ,2c,3d,1id .!:,},},.!: 5 Analogous lb,2c,3d,4ci .!:,},},5 "5 Highly analogous lc,2c,3c,1iC .!:,},},.!: ~ Highly analogous lc,2c,3c,4d .!:,},},.!: 2: Highly analogous Analogous ld,2d,3d,4d .!:,},},.!: ld,2d,3d,4d 1,3,3,1 ld,2d,3d,4ci !,},},! t] 5 Analogous Table C2

Comparison of Mobility Test Course and Mekong Delta Terrain TyPes

Terrain TyPes Mobility Test Course Mekong Delta Vor HV* SG or HG SC V or HV SG or HG SC Degree of Analogy 1,3a(1) !,1,1,! Highly analogous 1,3a (2) !,1,1,! Analogous 1,3b (1) !,1,1,! Analogous 1,3b(2) !,1,1,! 1,3b(2) 1,3,3,1 1 Analogous 2,3b(1) 2,2,2 Slightly analogous 1,2 !,1,1,! Highly analogous 2,2 3,2,3 iJ Slightly analogous Highly analogous 1,3a(1) !,1,1,! 1,3b(2) 1,3,3,1 2 !,3b (1) !,1,1,! ~j Analogous Highly analogous 1,3a(1) !,1.,1.,! 1,3b(2) 1,3,3,1 3 I,3b (!) !,1.,1.,! ~1 Analogous 1,3a(1) !,1,1.,! Highly analogous 1,3a(2) !,1,1,! 1,3b(2) 1,3,3,1 4 Analogous I,3b (1) !,1,1,! ~1 Analogous 1,3a(1) Moderately analogous 2,1,1,! 1,3b(2) 1,3,3,1 5 I,3b (1) !,1,1,! ~1 Analogous !,3a (1) ~,~,1,! 2 1,3b(2) 2,2,3,1 2 Highly analogous !,1E.(1) ~,1,1,! L 1,3b(2) 2,3,3,1 5 Analogous !,3a (1) ~,!,1,1 4 1,3b(2) 3,1,3,3 4 Highly analogous !,3a (1) 1,1,3,1 L 1,3b(2) 3,3,2,3 5 Moderately analogous ~,2a,3d,4d !,1,1,! 1 la,2a,3c,4d 1,3,3,1 1 Analogous la,~,3d,4d !,1.,1.,! 4 la,2a,3c,4d 1,3,3,1 4 Analogous la,2b,3c,4c 3,1.,1.,! 5 la,2b,3b,4b 1,3,3,1 5 Highly analogous lc,2d,3d,4d 3,2,1.,2 4 Moderately analogous Id,2d,3d,4d !,2,1.,! r Highly analogous Id,2d,3d,4d !,1.,},! 1 Analogous Id,2d,3d,4d !,1,1.,! 2 Analogous Id,2d,3d,4d !,1,1.,! 3 Analogous Id,2d,3d,4d 2,2,1.,! 4 Highly analogous Id,2d,3d,4d 2,1,1.,! r Highly analogous Id,2d,3d,4d 2,1.,1,! 2 Highly analogous Id,2d,3d,4d 2,1,1,! 3 Highly analogous Id,2d,3d,4d 1 Highly analogous 3,2,1.,! Id,2d,3d,4d 1,3,3,1 4 Id,2d,3d ,4d 3,1,1,! 1 Highly analogous Id,2d,3d,4d 1,1,3 3 Moderately analogous Id,2d,3d,4d 1,3,2 1 Moderately analogous Id,2d,3d,4d 1,3,3 1 Moderately analogous Id,2d,3d,4d 3,1,3 1 Moderately analogous Id,2d,3d,4d 3,2,2 3 Moderately analogous Id,2d,3d,4d 3,3,3 1 Moderately analogous Id,2d,3d,4d 3,3,3 2 Moderately analogous Id,2d,3d,4d 3,3,3 3 Moderately analogous Id,2d, 3d,4d 3,3,3 5 Moderately analogous ~,2d,3d,4d 2,1,},2 L ld,2d,3d,4d 1,3,3,1 5 Highly analogous

Note: The underlined factor classes shown under the mobility test course terrain types indicate that these factor classes also occurred in the Mekong Delta terrain type to which the comparison was being made. Under the columns beaded V or HV two numbers or a number and number-letter-number combination, i.e. 1,2 or 1,3a(1) indicate a hydrologic-vegetation association. A four number-letter combination, i.e. la,2a,3b,4d, indicates vegetation. In the columns headed SG or HG, three numbers, i.e. 1,1,3 indicate hydrologic geometry and four numbers, i.e. 1,3,3,1 indicates surface geometry. * V = vegetation HV hydrologic-vegetation association SG surface geometry HG hydrologic geometry SC surface composition DISTRIBUTION LIST A (For Distribution of TR's and MP's on Trafficability and Mobility Studies and Related Investigations) No. of Address Copies

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9 Unclassified Security Classification DOCUMENT CONTROL DATA· R&D (Security e/a.llllle.'ion 01 Utle, body 01 abetract lind IndeKln, IIIIno'.tlOII mus' be entered when 'h. over.1/ repor' ,. ct•••ltled) I. ORIGINATING ACTIOJITV (Corporat. author) z.. REPORT SECURITV CLASSIFICATION U. S. Army Engineer Waterways Experiment Station Unclassified Vicksburg, Miss. zb. GROUP

3. REPORT TI TLE

EVALUATION OF THE PERFDRMANCE OF THE XM759 LOGISTICAL CARRIER

4. DESCRIPTIVE NOTES (Type 01 report and Inclusive da'.s) Final report ". AU THORlS) (Flr.t name, m/delle Inltl.', ,••, name) Barton G. Schreiner Adam A. Rula

eo REPORT DATE 7., TOTAL NO. OF PAGES 171>. NO. OF 4EFS January 1968 151 ... CONTRACT OR GRANT NO. N. ORIGINATOR·. REPORT NUhf'BER(S)

b. PRO.JEC T NO. Technical Report No. 3-808

e. .b. OTHER REPORT NOIS) (Any other nUGllbere th., ...,. be •••, ..ed tide report)

10. DISTRIBUTION STATEMENT This document is sUbject to special export controls and each transmittal to foreign governments or foreign nationals may be made only with prior approval of U. S. Army Materiel Command. II. SUPPLEMENTARY NOTES 12. SPONSORING MILITARY ACTIVITY U. S. Army Materiel Command Washington, D. C.

'3. ABSTRACT The XM759 was tested at sites in Virginia and Louisiana on a wide range of terrain conditions analogous to those of the Mekong Delta, South Vietnam. The off-road performance of the XM759 was compared with that of an Ml16, 1-1/2-ton Cargo Carrier, Amphibi- ous, on the same test sites. Tests were conducted to (a) identify terrain conditions commonly found in the Mekong Delta and to locate analogous terrain in the United States that could be used for vehicle tests; (b) determine the off-road performance of the XM759 and the Mll6 on a wide range of terrain conditions occurring in wet, deltaic marshlands; (c) describe the terrain on which tests were conducted; and (d) evaluate tru: comparative performances of the vehicles on similar terrain. Trafficability tests were conducted on level terrain to determine (a) minimum soil strength, in terms of rating cone index (RCI), required for the vehicles to complete one pass (VCI1 ) and 50 passes (VCI50); (b) drawbar pull-slip relations for various soil strengths and vegetal covers; (c) drawbar pull-strength relations on a variety of surface vegetation; ( d) effect of soil strength and vegetal cover on vehicle turning radius and speed; and (e) maximum step height negotiable in exiting from bodies of water. Mobility tests were conducted to determine the average maximum safe speed while traversing straight-line courses that included more than one type of terrain in each traverse. Tests were conducted with empty vehicles and with vehicles loaded to 100% and 200% pay loads in 47 types of terrain. Of the 44 mobility test course terrain types used in the development of analog criterion, 16 were highly analogous to one or more terrain types identified in the Mekong Delta, 14 were analogous, 12 were moderately analogous, and 2 were slightly analogous. For the soft-soil areas selected in the Mekong Delta, it is estimated that

...~LACK. DD ... 0 '.71. , JAN ••• WHICH I. DD ,''=-..1473 O.80LKTK "'0" v U.K. Unclassified security Ct...lftcaUon Unclassified Security Classirication the XM759 with 100% pay load can traverse 100';0 of the areas for 50 passes, whereas the Ml16 with the same pay load can traverse only 89% of these areas for one pass and only 61% for 50 passes. The XM759 with 100% and 200';0 pay loads completed 50 passes on a soil strength as low as 2 RCI. The Ml16 with 100% pay load completed one pass on a soil strength of 7 RCI and 50 passes on 14 RCI. The experimental VCIl at 100% pay load for the XM759 was considered to be zero. The pneumatic tires and sponson of the XM759 provide buoyancy when they are immersed in soft, viscous soils, thereby reducing the effective weight of the vehicle. Closer agreement between experimental and com puted VCI' s can be achieved by considering the effect of buoyancy. The maximum draw bar pull of both vehicles at 100% pay load was limited because of insufficient power to develop sufficient force to shear the soil. On an RCI of about 75, the XM759 de veloped a maximum traction coefficient (TC) of 0.64 when empty and 0.49 with 100% pay load. On the same RCI, the Ml16 developed a maximum TC of 0.89 when empty and 0.75 with 100% pay load. On an RCI of about 7, the XM759 developed a maximum TC of 0.27 with 100% pay load. On the same RCI, the empty M1l6 was barely able to propel itself. For all vehicle weights tested, the motion resistance coefficient for the XM759 was 0.18 and 0.07 at RCI's of 4 and 75, respectively. For the same RCI's, the Ml16 developed a motion resistance coefficient of 0.34 and 0.14, respectively. Maneuver test results were not as definite as results of other performance tests; however, general trends indicate that the XM759 at 100';0 pay load can negotiate turns of slightly shorter radii than the Ml16 on RCI's between 40 and 8. On RCI's less than 8, the Ml16 could not negotiate turns; the XM759 negotiated turns on RCI's between 8 and 2 with a great increase in turning radius for a small decrease in soil strength. Data indicate that the XM759 can negotiate tighter turns on soil strengths between 12 and 40 RCI than it can on pavement. The XM759 and Ml16 at 100';0 pay loads negotiated maximum step heights of 2.2 and 2.8 ft, respectively. Mobility tests were conducted with the XM759 on 47 terrain types and the Ml16 on 35 terrain types. The XM759 negotiated 46 and the Ml16 26 terrain types. First-pass speeds ranged from 10.23 to 2.08 mph for the XM759, and from 11.25 to 2.22 mph for the Ml16. Of the 15 mobility test courses, the XM759 negotiated 14 and the Ml16 only two. First-pass speeds ranged from 11.18 to 2.56 mph for the XM759 and from 12.18 to 2.96 mph for the Ml16. An evaluation of the comparative performances of the XM759 and Ml16 in terms of terrain-vehicle relations (trafficability tests) and average speed for the terrain types tested (mobility tests) shows that the XM759 outperformed the M1l6 for most of the terrain conditions tested. Appendix A shows the computations necessary for deter mining VCI's of tracked vehicles. Appendix B presents a method for determining the effects of buoyancy on VCI's. Appendix C presents results of the terrain evaluation study to identify terrain types in several sections of South Vietnam and to locate similar areas in the Mississippi River Delta for vehicle test purposes.

14. LINK A LINK 8 LINK C KEY WORDS ROLE WT ROLE WT ROLE WT Ml16 cargo carrier Mekong Delta Mississippi River Delta Mobility Soils -- Strength Soils -- Trafficability Terrain analysis Vehicles, Military

Unclassified security CI•••lficalion