This technical report describes the road safety effect of the lowering of the general speed limit in built up areas from 60 km/h to 50 km/h. It reveals that the injury accidents dropped 9% while the number of fatalities was reduced 24% after the introduction of the 50 km/h speed limit in built up areas. In general, it indicates that speed limits in the period from 1974 to 1987 have reduced the fatality rate 38%. Another finding is that the accident rate in rural areas shows a decreasing trend from 1979 to 1987.