A comprehensive test program has been carried out to study the indicated effectiveness of personnel restraining devices in reducing injuries and fatalities in post office vehicle accidents. The program consisted of a series of simulated vehicle crashes utilizing a dynamic impact sled and three actual crash tests of postal vehicles.The seating configurations and restraint systems of the three basic types of postal vehicles were tested on the impact sled with an anthropomorphic dummy simulating the vehicle driver. Crash tests were simulated at various speeds, g levels, and angles of impact, with accelerometers and high-speed motion picture cameras used to monitor the significant variables observed during each impact test. At the conclusion of the simulated testing, a full-scale barrier impact test was conducted on each of the three types of vehicles under study.Certain changes in restraint system installations have already been initiated as a result of the information gained from these tests. Additional safety improvements will be incorporated in future vehicles as a direct result of this test program.