This report presents findings from an investigation into changes in traffic safety, especially of bicyclists, in the city of Delft. These changes have been related to the implementation of a bicycle enhancement plan during the period 1980-1987. Police accident records form the empirical basis for the measurement of traffic safety. Developments in traffic safety have been related to changes in kilometres travelled by car users and bicyclists (exposure). Apart from a comparison of Delft with developments in safety in other medium-sized Dutch cities and with the national average, the impact of the bicycle plan upon traffic safety in Delft has been studied using a before-and-after study employing test and control areas. Compared to similar cities, Delft appears to exhibit already a fairly high level of traffic safety, both for car users and bicyclists. The yearly average of traffic accidents in Delft is about 1500, a figure that did not change after implementing the plan. Despite a noticeable increase in bicycle kilometrage after the plan (+12%), a clear drop in accident numbers (-10%) as well as in accident risks for bicycles (-20%) could be observed in the same period. In particular bicycle accidents with cars and occurring at crossings decreased. To a small extent, the improved safety is due to the measures taken. The number of car accidents as well as the level of car exposure did not change during the analysis period. Also at the national level, bicycle safety shows an improving trend, though less strong than in Delft. (Author/publisher)
Abstract