Ministry of Transport and Public Works

Evaluation of the Delft Bicycle Network Plan

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EFFECTS OF THE DELFT DICYCLE NETWORK PLAN - Effects of bicycle plan on level of car use

An objective of the bicycle network plan is to reduce car travel by encouraging bicycle use. In the evaluation study, only limited attention has been paid to car travel. The investigation by ITS has established car mobility per capita by residents of both the study and the control area in the before and in the after situation. Furthermore SHT compared car traffic counts throughout Delft at both points of time. The effect of the bicycle network scheme can therefore only be established by comparing car travel per capita of the two areas.

Table 6 indicates that the study area inhabitants had a constant per capita car trip frequency, whereas the total kilometrage driven by car rose. It can be seen that the stability of car trip frequency is the net result of an increase in external trips and a decrease in internal trips. This shift results in a growth in total distance travelled by car since, on average, external trips are longer than internal trips.
Car use did not increase in the study period, despite an increase in car ownership.

Table 6: Changes in per capita car travel (passenger trips included) between 1982 and 1985 in percentages.

mobility indicator	inhabitants study area	inhabitants control area
car trip frequency	0 %	+15 %
internal trips Delft	-6 %	+25 %
external trips	+9 %	-1 %
total distance travelled by car	+10 %	+ 13%

In the control area on the other hand, both car trip frequency and car kilometrage of the inhabitants rose. In particular, internal car trips in Delft increased. Even when statistical uncertainties are taken into account, largely different changes in car travel can be noticed between the study and control area.
Below it will be shown that mode transfers from car to bicycle mainly stem from car passengers, as a result of which the reduction of car traffic in terms of vehicle volumes, due to the increased bicycle use, will be limited.
Counts showed a constant level of car traffic as far as entire Delft is concerned.
The differences between study and control area, combined with Stagnating car traffic volumes, indicate that the bicycle enhancement plan has contributed to restraining (an increase in) car travel.