Ministry of Transport and Public Works

Evaluation of the Delft Bicycle Network Plan

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SUMMARY AND CONCLUSIONS - Effects observed

With respect to the effects that are related to important objectives of the bicycle network plan, the main findings are:

1. Bicycle use

   The primary goal of the plan is to encourage cycling. It was found that due to the measures taken bicycle use per capita increased in terms of number of trips as well as in average trip length. As a result, the network plan caused total distance travelled by bicycle to increase by about 6 to 8 per cent depending on the type of trip. This figure does not include growth caused by other factors not related to the bicycle network plan. Various separate investigations that used different types of information like home interview survey results, traffic volume counts and simulation outcomes, came up with similar results on this point.

   This increase in bicycle use can be explained by two changes that took place simultaneously. First, the proportion of travellers for whom the bike is a feasible alternative grew substantially. This reduction of constraints to bicycle use is not related to the bicycle network plan. Second, the attractiveness of cycling relative to competing modes was improved as a result of the plan. This means that the enlarged group of travellers having a real choice to use the bike will use the bicycle more often.

   The increased bicycle use is caused by modal changes, especially by transfers from former walk and car passenger trips. There is no significant loss of public transport trips to the bicycle mode.

2. Route choice and network use

   The bicycle network plan had a large effect on cyclists' route choice in that they shifted their routes to a large extent to new and improved facilities. This shift to high-quality links caused at the same time a reduction of bicycle traffic at minor links of less comfort. As a consequence, some previously overloaded locations have been clearly relieved.
   The proportion of the separate and independent bicycle paths in total distance travelled by bicycle rose form 30 to 35 per cent, whereas cycling in mixed traffic fell form 45 to 40 per cent. It may be expected therefore that safety has been improved. This has to be shown by future investigations.

3. comfort and safety

   Cycling comfort and safety clearly improved as a result of the implementation of the bicycle network plan. Analysis of the network use by cyclists showed that the distance travelled by bike on separate and independent cycle paths increased twice as much as the total distance cycled in the network.
   Bicycle volumes on links with mixed traffic decreased. This improvement was also reflected by the results of the interviews into the perception of cycling conditions.
   

4. Car use

   A secondary objective of the bicycle network plan is to reduce car traffic by encouraging cycling. In the study area, where the provisions were made in the study period, the number of car trips did not increase. A striking finding is that in internal travel within Delft the number of car trips even fell. This is the segment of the travel market in which the bicycle is the most competitive compared to the car.
   Although the evaluation study does not allow to determine the true effect of the bicycle network plan, part of this decline may be attributed to the measures taken with certainty.

5. Competition between modes

   All these changes taken together resulted in a shift of the modal split: the share of the bicycle rose from 40 per cent to 43 per cent. The car and walking mode both remained stable at 26 per cent. Public transport share declined form 6 to 4 per cent. It should be noted, however, that these figures refer to trips made by residents of the study area. The total ridership of local public transport may at the same time increase due to trips by other travellers living outside Delft.
   The market position the bike compared to the competing modes clearly improved also in a more qualitative sense. Cycling conditions were enhanced. In addition, choice constraints preventing travellers from choosing the bicycle, diminished in such a way that a balance was achieved between potential loss to and potential gain from other modes. In particular, competitiveness of the bicycle relative to the car was improved.

6. Long-term effects

   The effects measured in 1985 by means of the after-study must for various reasons be regarded as underestimates of the effects that are expected to occur in the long-term. By the end of 1985 the bicycle network scheme was not fully implemented; a number of major projects, essential to the coherence of the network, were not completed. Examples are: Plantage Bridge, Railway Station Tunnel. Furthermore, it is well known that travellers need some time to get informed about new routes and their properties. Learning processes take place before a new equilibrium in the transport system is reached. In view of the design of the evaluation study, only direct and short-term responses related to travel decisions can be established. Individuals modify their behaviour also in an indirect manner on the long-term, but only after certain changes in their personal circumstances took place. Expectations are therefore that in the long term effects of the bicycle network plan will be larger than those that were found in this study.