Engineering Specification for Construction of Truck Only and Vehicle Only Travelways in Missouri Phase 1
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Organizational Results Research Report September 2009 OR10.008 Engineering Specification for Construction of Truck Only and Vehicle Only Travelways in Missouri Phase 1 Prepared by Wilbur Smith Associates and Missouri Department of Transportation FINAL REPORT RI08-030 Engineering Specifications for Construction of Truck Only and Passenger Vehicle Only Travelways in Missouri Phase 1 Prepared for the Missouri Department of Transportation Organizational Results Division By: September 2009 The opinions, findings and conclusions expressed in this report are those of the principal investigator and the Missouri Department of Transportation. They are not necessarily those of the U.S. Department of Transportation or the Federal Highway Administration. This report does not constitute a standard, specification or regulation. TECHNICAL REPORT DOCUMENTATION PAGE 1. Report No. 2. Government Accession 3. Recipient's Catalog No. OR10-008 No. 4. Title and Subtitle 5. Report Date Engineering Specifications for Construction of Truck Only and Passenger Vehicle Only Travelways in Missouri – Phase I 6. Performing Organization Code 7. Author(s) 8. Performing Organization Report No. Wilbur Smith Associates RI08-030 9. Performing Organization Name and Address 10. Work Unit No. Wilbur Smith Associates 10401 Holmes Road, Suite 210 11. Contract or Grant No. Kansas City, MO 64131 12. Sponsoring Agency Name and Address 13. Type of Report and Period Covered Missouri Department of Transportation Final Report Organizational Results 14. Sponsoring Agency Code P. O. Box 270-Jefferson City, MO 65102 MoDOT 15. Supplementary Notes 16. Abstract The objective of this study is to provide information detailing the safety consideration specifications for the truck only and passenger only facilities for I-70 and I-44. The categories discussed in this report include: Traffic Operation and Truck Only Lane (TOL) Configuration, Public Policy Questions, Literature Review, and Public Outreach Tools. 17. Key Words 18. Distribution Statement Truck Only Lanes No restrictions. Slip Ramps 19. Security Classification (of this 20. Security Classification (of this 21. No. of Pages 22. Price report) page) Unclassified Unclassified 482 Form DOT F 1700.7 (06/98) Engineering Specification for Construction of Truck Only and Passenger Only Travelways in Missouri – Phase 1. RI 08 – 030. Table of Contents: Executive Summary. Truck Only Lanes Talking Points. Slip Ramp Spacing Technical Memorandum. Slip Ramp Safety Features Technical Memorandum. EMS Access to Truck-Only Lanes Technical Memorandum. Public Policy Technical Memorandum. Literature Review on Effectiveness of Guard Cables with Trucks and Truck-Only Lanes. Literature Review on Safety Considerations for Truck and Truck- Only Lanes. Public Outreach Promotional Strategy. Truck-Only Lane Promotional Tools. Truck-Only Lane Survey of EMS Providers. I-70 Truck Only EIS Freight White Paper Literature Review. Appendix - EMS Survey Package. Engineering Specifications for Construction of Truck Only and Passenger Vehicle Only Travel ways in Missouri ‐ Phase I: RI08‐030 Executive Summary Executive Summary To improve safety and the efficiency of freight movement on I‐70 and I‐44 across Missouri the Missouri Department of Transportation (MoDOT) is investigating the possible separation of truck traffic from general purpose vehicles. The I‐70 Supplemental Environmental Impact Statement (SEIS) completed in the summer of 2009 recommended truck‐only lanes be separated from general purpose lanes by 30 to 40 foot grass medians. As part of this continuing effort, MoDOT contracted Wilbur Smith Associates and the Missouri University of Science & Technology to study a variety of issues entitled Engineering Specifications for Construction of Truck Only and Passenger Vehicle Only Travel ways in Missouri. Figure 1 Proposed Truck‐Only Lane Slip Ramp Configuration...1 This report consists of the following nine technical memoranda covering Slip Ramp Spacing, Slip Ramp Safety Features, EMS Access to Truck-Only Lanes, Public Policy on enforcement, Effectiveness of Guard Cables with Trucks, Safety Considerations for Truck‐Only Lanes, Public Outreach Promotional Strategy, Truck‐Only Lane Promotional Tools, and a Truck‐Only Lane Survey of EMS Providers. 1 http://www.improvei70.org/pdf/08-04-01Handout.pdf (Spring '08 handout) 1 Engineering Specifications for Truck Only Lanes ‐ Executive Summary Slip Ramp Spacing The investigation into slip ramp spacing used a VISSIM micro traffic simulation model to investigate the proper spacing or location of slip ramps. The slip ramp spacing study made the following recommendations based on safe and efficient operations of the general purpose lanes: 1. Slip ramp design speed should be the same as the general purpose lanes. 2. The distance for trucks to weave in traffic is greater than the distance to accelerate or decelerate therefore the weaving distance controls the length of the acceleration/deceleration lanes, 3. Acceleration (merge) lanes should be 1,000 feet for moderate and 1,200 feet for heavy traffic. 4. Deceleration (diverge) lanes should be 800 feet for moderate and 1,000 feet for heavy traffic. 5. Weaving for trucks requires 1,500 feet for moderate and 2,000 feet for heavy traffic. 6. The total distance from slip ramp to off‐ramp should be 3,300 feet to 4,200 feet. 7. Operations degrade for traffics flow between 150 and 200 trucks per hour and between 1,600 and 2,000 general purpose vehicles per hour. Figure 2 Slip Ramp Spacing Configuration Slip Ramp Safety Features The investigation into safety features of slip ramps found or recommended the following: 1. Most literature covers HOV or managed lanes with limited specific research on the safety features of truck‐only lanes. 2 Engineering Specifications for Truck Only Lanes ‐ Executive Summary 2. The AASHTO High Occupancy Vehicle (HOV) Design Guide2 allows the use of slip ramps due to limited right‐of‐way and/or high costs. 3. Safety improves with driver’s familiarity therefore Missouri should consider a public education campaign on of truck‐only lanes and slip ramps. 4. Slip ramp design should be location specific based on grades, speed limits, weaving distances, lane widths, median widths, etc. 5. Most safety issues involve the truck merging maneuvers from the left slip ramps to the right side exits. A 1992 study by the Texas Transportation Institute suggested merging distances of at least 3,500 to 3,750 feet which is consistent with the 3,300 to 4,200 feet recommended in the slip ramp location technical memorandum in this report. 6. Clear signage will be instrumental for the safe operation of truck‐only lanes and creating designated truck merging zones may improve driver’s expectations. 7. Critical geometric design criteria for slip ramp operations should be completed when investigating longer combination vehicles (LCVs). 8. Technologies are emerging that may increase safety at slip ramp facilities including ITS, ramp metering, vehicle detection, and on‐board blind spot detection. EMS Access to Truck‐Only Lanes This technical memorandum looked into the configuration and spacing of special access to truck‐only lanes for emergency services. The memorandum recommended the following: 1. Current MoDOT standards for median crossovers are adequate for access across the medians to the truck‐only lanes. 2. Emergency access opening in the truck‐only lane median barriers should be lined up with the median crossovers (see figure 2.) 3. Mechanical gates or temporary access points may be required in locations with narrow shoulders adjacent to concrete traffic barriers. 2 Guide for the Design of High Occupancy Vehicle Facilities. American Association of State Highway and Transportation Officials, Washington, D.C., 1992. 3 Engineering Specifications for Truck Only Lanes ‐ Executive Summary Figure 2 Proposed Rural EMS Access Public Policy Technical Memorandum The Public Policy Technical Memorandum discusses how to define trucks and enforce truck restrictions in the general purpose lanes. The memorandum discusses and recommends adopting existing federal rules on the definition of trucks and existing truck limitations used across the country. To help define the restriction on truck use of the general purpose lanes to local trips study recommends three options: 1. Distance from a trucks origin or destination to define local trips. 2. Commercial vehicle configuration as they differ between long and short hauls. 3. Purpose of the trip, a truck may only use the general purpose lanes to gain access for their intended purpose. The enforcement recommendations borrow from the “virtual weigh station” concept currently in use across the country where information about the truck is encoded into an electronic manifest system available to law enforcement. Effectiveness of Guard Cables with Trucks and Truck‐Only Lanes The technical memorandum on the effectiveness of guard cables on trucks found little literature dealing with of truck‐only lanes and trucks except for those that measured failure of cable barriers in median crossover accidents. The studies that did measure crossover failures did not compare these to the number of successful applications involving trucks. However, these studies did indicate that guard cable greatly decreased injury and fatality accidents, prevented general purpose vehicles from 4 Engineering Specifications for Truck Only Lanes ‐ Executive Summary crossover accidents, and actually increased minor