Through the Australian Design Rule program, action has been taken to make seat belts more convenient, more comfortable to use and more effective in accidents. Inertia reel lap sash belts for front outboard positions and improved upper anchorage locations for all outboard-seating positions became compulsory for all passenger cars and derivatives manufactured on or after 1 January 1975. These represent the most recent major efforts to improve restraint system in these vehicles. In March 1978 the Office of Road Safety conducted a roadside survey of seat belt fitting and wearing in four Australian cities. In one city, Melbourne, registration plate numbers were obtained to enable calculation of fitting and wearing rates by year of vehicle manufacture.