Adaptive behaviour in traffic : An individual road user perspective

Sammanfattning: Road-user adaptation is a prerequisite for traffic to run smoothly. By adaptation, the road user aims to ensure a feeling of comfort according to his or her present state and capability. In this thesis, adaptive behaviour of car drivers and cyclists in response to different factors is explored, using the individual perspective of the road user. The research focuses on investigating how adaptation in the road traffic environment can be described, and what adaptations road users make in traffic in response to static and dynamic infrastructure, additional tasks and other road users.One simulator study and three field studies in real traffic were carried out. The study results implied that the current road-user role and the preconditions for that role, in terms of vehicle and infrastructure, affect adaptive behaviour. The results also showed that in non-complex situations, there is a certain level of visual guidance above which more detailed information does not have any effect on speed adaptation. Detailed information that allows road users to improve their predictions to take action to ensure a feeling of comfort, is however preferred. Under increased situational demands, vehicle speed can be reduced to maintain the safety margins. It was found that there are individual strategies concerning what degree of complexity for interaction with an additional task is acceptable.A conceptual model of adaptation in relation to the environment and subjective perceptions of safety and a feeling of comfort is proposed and applied to different traffic situations. For future transport system designs it is advised that adaptive behaviours of road users are supported.