Microscopic simulation of pedestrians in accessibility evaluation

Evaluation of accessibility is of increasing importance to the design of the public realm – including both the built and moving environments and particularly the interface between them. This is of particular relevance to people who are living on the ‘margins of accessibility’ – for example elderly or disabled people – for whom the possibility of reaching an activity really is dependent on whether they can negotiate an obstacle such as boarding a bus. This paper discusses the conceptual nature of the problem by considering the interactions between a person, the environment and the activities they wish to pursue. A barrier is seen as the outcome of an interaction between an individual and some element of the environment which results in the person being unable to complete an action which is necessary for success in the chosen activity. The paper proposes a model which incorporates the concept of ‘capabilities’: those required by the environment in order for an action to be completed and those provided by a person who intends to attempt the action in that environment. The paper then describes how the systematisation of these concepts could be tested by incorporating them in a microscopic simulation model of pedestrian activity. A worked example is used to demonstrate how the conceptual approach could yield consistent results under these circumstances. The paper concludes that the conceptual model provides a good basis for the evaluation of accessibility and that the microscopic simulation model incorporating these characteristics would be a useful way of testing pedestrian-environment interactions.