Ministry of Transport and Public Works

Evaluation of the Delft Bicycle Network Plan

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EXPLANATION OF CHANGES IN TRAVEL BEHIAVIOUR - Modal transfers

To change modal choice is the central objective of the bicycle network plan. The analyses of effects showed that the bicycle share in the modal split actually rose from 40 to 43 per cent.
In order to determine to what extent this change is due to modal transfers a panel of persons making similar trips in 1982 and 1985 was surveyed. In this group modal transfers occurred: 8 per cent of the 1985 bicycle trips were made by a different mode in 1982. In the same period the bicycle lost 2 per cent of its trips to other modes. As was discussed in section 6.4 the bicycle mode attracts trips from all other modes, but predominantly from 'walking' and 'car passenger'.

In order to explain the observed transfers all choice elements to are checked on potential changes due to the plan:

• on extension of the objective choice set (new modes) is very unlikely;
• the improvement of the objective accessibility of destinations by bicycle, relative to other modes was an important factor. Although distance and travel time reductions were limited, comfort and safety have been improved substantially. This enhancement stems from the amelioration of existing routes (resurfacing, separate cycle paths) as well as from the construction of new routes.
• choice constraints on bicycle use have diminished strongly between the before and after situation. As was explained in section 6.5 only a small part of this reduction can be ascribed to the measures taken. It implies however that the group of unconstrained trips, i.e. trips that could be made by bike, grew considerably. If the bicycle mode is made more attractive than the competing modes, it will be effectively used for these trips.
• it is plausible that the perception of the bicycle travel alternatives and its related attributes has been improved because of the implementation of the plan.

Modal transfers are the chief cause of the increase in the number of bicycle trips per capita. As total trip frequency per capita remained constant, the transfers also result in a larger modal share of the bicycle.
These modal transfers to the bicycle are partly the result of the growth of the class of unconstrained trips, and partly due to the increased attractiveness of the bicycle mode. In the latter case travellers with a choice will more often opt for the bike.

It should be realized that the panel trips for which modal transfers could be analysed, relate only to half of the total trips made in 1985. The other half are 'new' trips, made e.g. by residents that moved into the study area during the study period. From the aggregate figures it may be concluded that new residents choose more often the bike than residents who left the area in the same period.