Pedestrian mobility and accessibility planning: some remarks towards the implementation of travel time maps

The objective of the paper is to propose a methodology for evaluating pedestrian accessibility in urban areas. Accessibility is a quite recurring topic in the scientific literature, and emphasizes the strong interrelationships between land use and mobility. In the last decade, dependence on GIS-based approaches for accessibility assessment and management has grown considerably, and the crucial role of GIS techniques for the analysis of accessibility is nowadays well established. With particular reference to the Organic Urban Planning vision developed in Italy in the ‘60s in Italy, the paper focuses on pedestrian accessibility as major mobility mode at the scale of the neighborhood. But how is it possible to measure the level of pedestrian accessibility of a given territory and to map the results in a GIS environment? First of all, there is a need to collect the different layers of information related to pedestrian mobility for the area, with particular reference to the road network, the location of pedestrian paths and sidewalks as well as the presence of physical barriers in the area that impede pedestrian permeability (built environments, railways, waterways surface...). The proposed assessment methodology is based on the detailed discretization of the area being analyzed in a uniform grid of cells. In this grid a calculation algorithm is applied. This algorithm, on the basis of the information layers that overlap in each cell, assigns each cell a pedestrian travel time and evaluates the existing connections between the cell in question, and the cells adjacent to it. This model allows the creation of thematic maps that show the timing of pedestrian access to each cell.