Analyzing accessibility to fire stations: A floating catchment area model for stochastic transportation networks with travel time correlation

Improving the spatial accessibility of fire stations is a key factor in minimizing property loss and reducing injuries and deaths. Most existing studies neglect the effect of travel time correlation and uncertainty on the level of accessibility in non-normally distributed networks. In this article, a two-step floating catchment area (2SFCA) model is introduced to measure accessibility in correlated non-normal uncertain transportation networks. The model extends the conventional 2SFCA measures by considering the catchment area of supply and demand locations in stochastic contexts. The proposed measure is applied to a study area to investigate the impacts of travel time correlation, travel time uncertainty, and non-normal distributions on the accessibility value. It is further used to analyze access inequality between different areas of the case study and to identify segregated places in terms of accessibility to the fire stations. In addition, the conventional 2SFCA measure is executed to provide an evaluation of the outputs of the proposed model. Results highlight significant difference between the introduced model and the other existing measure. They also show inequality of accessibility in the study area and the way that the model parameters affect the accessibility level. Furthermore, results offer several methodological implications for accessibility analysis in time-dependent networks.