Making minor rural road networks safer: The effects of 60 km/h-zones.

For safety reasons a maximum speed limit of 60km/h has been applied to minor rural roads in the Netherlands since 1998. To support this structurally, a part of these roads have also received additional physical measures in a so-called "low cost design" that is expected to reduce the number of traffic casualties by 10-20%. This measure has been implemented as much as possible in an area oriented way. To measure the design's effectivity, road safety in 20 specific rural areas was studied for 5 years before changes were implemented and, on average, 3.5 years thereafter. The study examined 851km of roads, and a control study was done on 2105km of comparable roads with a speed limit of 80km/h. Both the study and the control roads are managed by water boards. Results show that the measures implemented on the roads in the 60km/h-zones had statistically significant effects (p<0.05) on casualty accidents (-24% overall), especially at intersections (-44%). This high reduction is probably caused by the concentration of technical interventions at intersections. Both outcomes are somewhat higher than previously expected and are comparable with the outcome of a meta-analysis of safety effects on area-wide urban traffic calming schemes. However, the cost-effectiveness ratio of the 60km/h zones measures (€33,000 per prevented KSI-casualty) is much more favourable than the ratio in urban 30km/h-zones (€86,000 per prevented KSI-casualty).