To understand the dynamics of pedestrian and bicycle flows in an urban context and subsequently show the main knowledge gaps, we break the behaviour down into three different behavioural levels, using decision-making timescale as the prime classifier. The knowledge acquisition level pertains to the way pedestrians and cyclists acquire and represent knowledge, i.e. learn about the environment they are traveling through. Given this knowledge, travellers determine how to schedule their activities, choose the locations to perform the activities, as well as the routes towards these locations. These choice processes constitute the activity-travel level. Finally, once the activity schedules, activity locations, and routes have been decided upon, travellers will move along these routes – possibly rescheduling along the way – interacting with other traffic participants of the same mode, and of others, constituting the walking or cycling traffic operations level. The figure shows these levels, including the relation with the infrastructure characteristics and impact of ICT, described in more detail when discussing the behavioural levels below.

We will discuss these levels in the next pages, starting with the operational level.

Figure 2 Behavioural levels and their relations.