EVALUATION of the COMFORT and CONVENIENCE of SAFETY BELT SYSTEMS in 1980 and 1981 MODEL VEHICLES
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DOT HS-805 860 EVALUATION OF THE COMFORT AND CONVENIENCE OF SAFETY BELT SYSTEMS IN 1980 and 1981 MODEL VEHICLES J. C. Tom D. D. Petersen C. M. Robbins R. Peters Verve Research Corporation Seventeenth Floor - 51 Monroe Street Rockville, Maryland 20850 Contract No. DTNH-22-80-C-07011 and Contract No. DTNH-22-80-C-07611 Contract Amt. $209,907.91 MARCH 1981 FINAL REPORT This document is available to the U.S. public through the National Technical Information Service, Springfield, Virginia 22161 Prepared for U.S. DEPARTMENT OF TRANSPORTATION National Highway Traffic Safety Administration Washington, D.C. 20590 This document is disseminated under the sponsorship of the Department of Transportation in the interest of information exchange. The United States Govern- ment assumes no liability for its contents or use thereof. * * Technical R.port Documentation Page 1. Report No. '2 G .,mnent Ac, ea•.n,n No. :1. Recipient'. Catalog No. DOT-HS-805-960 4. Title and Subtitle 5. Report Dote March 1981 Evaluation of the Comfort and Convenience 6. Performing Organization Code of Safety Belt Systems in 1980 and 1981 Model Vehicles B. Performing Organization Report No. 7. Authorr s) J.C. Tom,D.D. Petersen,C.M. Robbins, R. Peters VS-77/83 9. Performing Organization Name and Address 10. Work Unit No. (TRAIS) Verve Research Corporation Seventeenth Floor-51 Monroe Street 11. Contract or Grant No. Rockville, Maryland 20850 13. Type of Report and Period Covered 12. Sponsoring Agency Name and Address FINAL REPORT Department of Transportation November 1979- May 1980 National Highway Traffic Safety Administration _june - Febr uary 1981 Office of Driver and Pedestrian Research 14. Sponsoring Agency Code Washington, D.C. 20590 NHTSA/NRD-40 15. Supplementary Notes *This report represents the results of work done under two contracts numbered DTNH-22-80-C-07011 and DTNH-22-80-C-07611. 16. Abstract An analysis was conducted of both user and vehicle characteristics that influence the user perceptions of safety belt system comfort and convenience. A research design was developed involving various passenger cars, vans, and pickups, and a set of drivers of different sex, weight, and height combinations. A statistical analysis of the test results using crosstabulation and analysis of variance identi fied height, vehicle size, type of belt system, and other factors as having a significant impact on perceptions of safety belt comfort and convenience. An additional phase of these studies examined the compatibility of child restraint devices with existing safety belt systems. Several devices currently available on the open market were evaluated in each of the test vehicles. Problems identified include the need for special locking devices in some vehicles, the incompatibility of automatic belt systems, and bulky retractor devices. 17. Key Words 18. Distribution Statement Safety Belts Document is available to the U.S. Automatic Safety Belts Public through the National Comfort and Convenience Technical Information Service, Child Seats Springfield, Virginia 22161 Child Restraint Devices 19. Security Clossif. (of this report) 20. Security Clossif. (of this page) 21. No. of Pages 22. Price 291 Unclassified Unclassified Form DOT F 1700.7 (8-72) Reproduction of completed page authorized i * METRIC CONVERSION FACTORS Approxim.ts Coovoislons to Metric Measures Approximels Conversion trout Metric Mossuies Symbol Whom You KNOW Multiply by To Fie/ Symbol symbol When, Yeti Knew Multiply by To fiat Symbol * LENGTH LENGTH Iran m1116metars 0.04 lches In 8 cm centimeters 0.4 inches in an m.1118 3.1 lost It in inches - Z.6 centimeters cm m nytsrs 1.1 vw4s yd It her 30 csnunrters cm .r. km kllonslars 0.6 miles ml yd yards 0.9 maters in all miles 1.6 kilmwams km a AREA AREA cm2 square contumelters 0.16 2.4.+are caches Inl let 3d2 square inches 6.6 square conumetms cm2 m2 square melsrs 1.2 saw'* reeds squat. meters 2 Ill square feet 0 .09 ml km square kilometers 0.4 sq..s.e miles m12 yd2 squall Voids 0.9 square meters m2 • be, hectares (10.000 m2l 2.6 sus. m/2 agues miles 2.6 square kilonwtms km2 acres 0.4 h.cta.as he * MASS (wsiiIj MASS (wed g gram 0.036 muicas or or ounces 26 grams g kg kilograms 2.2 pwn.a Ib Ib pounds 0.46 kilograms kg tonnes (1000 kgl 1.1 51.911 lints steal 1-* 0.9 tmelas t * 12000 Ibl w 0 VOLUME VOLUME a. fluid ounces lap teaspoons 6 milliliters ml ml mllliluara 0.03 1161 pints Thep tablespoons 16 milliliters ml lit.'s 2.1 94 4".18 ill It or fluid ounces 30 milliliters all liters 1.06 c cups 0.24 liters Ill.'s 0.26 gallons gal pt pints 0.47 liters ml cubic ntetars 36 cu1lc feet I12 ill quart. 0.96 liters m2 cutlc a.erera 1.3 cubs yards yd3 le gal gallon. 3.6 liters * 112 cubic lent 0.03 cublc, maters 3 y ^ ^ N yd2 cubic yards 0.76 cubic meters m2 TEMPERATURE losscl 94 TEMPERATURE Iexect) Colslu. 9/6 (Half FJ..eMlt . 1, lrrpmotwe * laiyeraluu *0 321 . F Fahrenheit 6/9 letter Celsius .C Ismpe'slure aubuacting tempmatwo .r 321 212 N °r 34 66.6 too -40 0 140 e0 1 . 1x0 160 1 . ..^..^. ' I ,., • 2.!.i 1.:•.c.lil, I,e ..ewr un.w l :.....I .,-. .bl.,lm1 latll.:s..o. NOS M.al. P.iN. 2W. t It s0 s0 I Uud. ut 6.,9.1 and Me...6, Pr¢o $2.1S. SU karat,., No. C13.10:206. -40 -20 • 10 r 140 at; .C 97 * EVALUATION OF THE COMFORT AND CONVENIENCE OF SAFETY BELT SYSTEMS IN 1980 AND 1981 MODEL VEHICLES EXECUTIVE SUMMARY This report presents the results of two studies designed to identify the comfort and convenience problem areas in 1980 and 1981 model passenger cars, vans, and pick-up trucks, and to find vehicle and user characteristics that influence comfort and convenience. In addition, the compatibility of various child restraint devices with the passenger seat belt systems was also examined. The comfort and convenience evaluation procedure, which is patterned after one developed for an earlier study, was conducted in two parts. The December session concentrated on 1980 model vehicles including vans and pick-ups. The July session examined 1980 model passenger automobiles that would be unchanged during the 1981 model year. During both sessions, approximately 120 licensed drivers of both sexes and a range of heights and weights were selected to evaluate each test vehicle belt system. These test vehicles were selected to represent the various safety belt systems most commonly purchased in domestic and imported cars and trucks. Each evaluation consisted of a test participant using the safety belt system of one of the test vehicles. While putting on and taking off the belt system, the participant was asked to identify the extent of any problems with various comfort and convenience aspects of safety belts. Each individual participant tested the vehicles in a different randomly selected order, to eliminate the effects of always testing vehicles in the same order. For purposes of these studies, the operation of safety belt systems was divided into seven aspects: • Accessibility, relating to reaching for and grasping the safety belt latch plate; • Extending, pertaining to moving the latch plate over to the buckle; • Buckling, involving inserting the latch plate into the buckle; iii • Fit, describing how the shoulder belt fits the wearer; • Pressure, relating to the pressure of the belt on the wearer's chest and shoulder; • Releasing, involving releasing the latch plate from the buckle; and • Retracting, relating to how conveniently the system retracts out of the user's way upon exiting the vehicle. To analyze, these aspects of safety belt comfort and convenience, indices were developed based on participant responses for each of these aspects and for overall comfort and convenience. The indices were statistically analyzed using contingency tables and analysis of variance to determine which driver and belt system characteristics had significant impact on each aspect. The major results of this analysis are: • The problem most frequently identified by test participants was accessibility. In general, safety belt systems considered more comfortable and convenient by one weight group were ranked the same way by other weight groups. On the other hand, short-overweight individuals tended to rate safety belt systems as a whole lower than other participants. The participants in the July evaluation session indicated that all comfort and convenience aspects were equally important in an overall evaluation of a safety belt system. This finding substantiates the use of an index that weights each aspect equally. The user characteristics that have statistically significant impact on safety belt comfort and convenience are weight, height, and sex. Shorter and overweight subjects had more problems with safety belt systems as a whole than did others. Belt system and vehicle characteristics that have statistically significant impact on user comfort and convenience perceptions are vehicle size, type of belt system, type of seat, and number of vehicle doors. In general, larger vehicles, dual retractor systems, bench seats, and four-door vehicles had fewer problems. • Belt systems satisfying the compliance tests for belt fit and pressure were found by test participants to be more acceptable. • The main compatibility problems between safety belt systems and child restraint devices are that belts are sometimes too short and that special locking devices are sometimes required to secure a child restraint. Also, automatic systems are not compatible with child restraint devices without modifications or the addition of a special belt. iv CONTENTS PAGE EXECUTIVE SUMMARY iii 1 . INTRODUCTION 1 Background Purposes of the Studies 4 Organization of the Report 5 2.