Between July 1st 1964 and June 30th 1965 an experiment was conducted on six roads in different parts of the country to determine the effect on speed and accidents of increased police enforcement of the 30 mile/h speed limit. Additional enforcement was carried lout by the normal methods of motor patrolling and kerbside radar speedometer, with warning op prosecution folk offenders. Regular speed measurements were made on the six roads both before and during the experiment and the police supplied the laboratory with accident data for these roads for the period of the experiment and for the 12th month period preceding it. The following represent the main conclusions: I. Speeds were in general reduced on the experimental roads. II. Police action reduced injury accidents by 25 per cent on the experimental roads. In addition accidents in the surrounding areas fell by 7 1/2 per cent compared with the national trend for roads with a speed limit. III. Although all classes of road user had fewer casualties, drivers and passengers were most affected with more than a 50 per cent reduction. IV. The cost of large-scale enforcement of the limit on main roads would probably not be balanced by the reduced cost of accidents on these roads alone, but the benefit on all urban roads would probably balance the cost.
Samenvatting