Ministry of Transport and Public Works

Evaluation of the Delft Bicycle Network Plan

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THEORETICAL FRAMEWORK - Choice theory

• Activity and travel choices

  The travel pattern is a derivative of the individual's activity pattern. This means that if the activity pattern changes, e.g. in terms of frequencies, points of times, duration, sequence and location, the individual's travel choices will necessarily be adapted. The choice of activities may be affected by the bicycle network plan.
  A modification of the activity pattern thus results in a different trip frequency, different mode, different distance travelled, etc.. Changes in the activity pattern can be derived from the distribution of trips by trip purpose.

  Travel behaviour encompasses all choices related to trip timing and mode used. Four dimensions of individual travel behaviour will be dealt with in view of possible effects of the bicycle network plan:
  
  

  • choice to make a trip (trip frequency)
  • destination choice
  • mode choice and
  • route choice.

  It is assumed that trip frequency and destination choice are indirect decisions which depend upon the activity pattern, whereas mode and route decisions are made directly and enable an immediate response to improvements of the bicycle network. The diagram below illustrates the way these four choice dimensions affect total distance travelled by bicycle.

  Missing scheme: Activity and travel choices

• Elements of the choice process

  Activities carried out and trips made can be viewed as outcomes of choice processes. Individuals choose more or less rationally from various options available to them, based on their personal taste and preferences.

  A traveller has available number of alternatives (e.g. modes, routes), each having a variety of attributes. It is on the basis on these attributes that the individual traveller evaluates the attractiveness of the alternatives. Examples of such attributes are travel time, comfort, safety. Both these elements define the objective choice situation.
  On the other hand personal and subjective characteristics of the traveller play an important role in travel choice processes. Due to his personal circumstances not all existing alternatives are feasible to him for the trip to be made. These constraints are both of a more objective nature (e.g. bicycle ownership, car availability, physical handicaps) and of a subjective type (e.g. personal perception of travel times and distances, lack of knowledge about existing alternatives).
  Choice restraints result in a much more limited subjective choice situation, having less alternatives and attributes perceived differently. The traveller will evaluate the advantages and disadvantages of these alternatives. Given his personal preferences and taste with respect to travel time, safety, convenience etc., he will trade off the relevant attributes. It is assumed that he tries to maximize his utility which means that he selects the a1ternative that is most attractive to him. Utility or attractiveness is a weighted combination of all relevant attributes.

  The next scheme illustrates the essential elements of the choice process. The bicycle network plan may in principle affect objective (impersonal) as well as subjective (personal) aspects. The way these choice elements (alternatives, attributes, constraints, perceptions, and preferences) might have been affected by this plan will be discussed later.

  Missing scheme: Choice Process

  Certain effects, in particular those on the perception of alternatives and attributes, grow to their full extent only after a longer period, during which travellers get acquainted with the enhanced bicycle network.