THE EFFECTS ON TRAFFIC SAFETY OF THE SPEED LIMIT CHANGES IN 1976

This study deals with the effects on traffic accidents of the changes made in the road section speed limit system in 1976. The study was made as a statistical investigation by comparing the number of accidents during the year-long study period (1.7-30.6 or 1.10-30.9) after the speed limit change to the accidents of the previous study periods. The groups of changes with the largest observation material were the 120 kmph change to 100 kmph on 646 km, the 100 kmph reduction to 80 kmph on 473 km, and the 60 kmph change to 80 kmph base speed limit on 688 km. The effects of the speed limit changes on accidents were found to be very similar to the results obtained before during the speed limit experiment in 1973-76. When speed limit values are raised, the number of accidents increase and a speed limit reduction causes a decrease in the number and severity of accidents, unless there are at the same time significant changes in road, traffic or environmental conditions which affect traffic safety the opposite way. (TRRL)