SEAT BELT USE-INDUCING SYSTEM EFFECTIVENESS

Seat belt use inducing system effectiveness was measured in fleet automobiles of a private business and in rental automobiles at a large airport. There were three parts to the activity: 1. Seat belt use inducing systems and seat belt use counting systems were installed in 30 fleet vehicles of the Automoible Club of Southern California (ACSC). The vehicles were driven on work related and personal business by ACSC employees whose seat belt use habits were known. Hardware was retrofitted to the vehilces and consisted of a 1974 seat belt system, a seat belt use counting system and electronic vehicle modifications which provided the following use inducement methods: a. Ignition interlock system; b. Sequencing system; c. Speed limiting system. The test subjects were subjected to the use inducing systems in various sequences and for varying periods of time, during which bi-weekly counts of seat belt use were recorded. The seat belt count data was compiled are analyzed for significance using "t" tests: There was a significant increase in seat belt use for all three (3) methods of use inducement. There was no significant difference in seat belt use between the three methods of use inducement. There was no significant change of seat belt use for any of the three (3) inducement systems according to time of exposure. There was a significant difference between previous no system seat belt use and no system seat belt use, the latter being higher, after exposure to the use inducing system. The test subjects were periodically administered a questionnaire, the results of which indicated higher self reported than actual seat belt use and specific confusion, inconvenience discomfort factors. 2. An observation study was performed to determine the shoulder belt usage of ACSC employees as they drove their assigned 1974 fleet vehciles into an ACSC parking lot equipped with interlock systems 540 of 750 (72%) observations showed correct shoulder belt use. One non seat belt user was induced to wear seat belts by modifying the seat belt system. Additional data on make of vehicle and sex of drivers was obtained. 3. An observation study was performed to determine the shoulder belt usage of occupants of 1974 rental automobiles at Los Angeles International Airport equipped with interlock system. 1,823 drivers were observed of which 1,281 (70.3%) were wearing shoulder belts. 472 front passengers were observed of which 287 (60.8%) were wearing shoulder belts. Additional data on make of vehicle and sex of occupant was obtained. /HSRI/