Pedestrian exposure measures: A time-space framework

Modeling pedestrian-vehicle crashes is a spatially complex and temporally dynamic process. Examining the probability of and degree to which pedestrians are exposed to pedestrian-vehicle crash risk has important implications for formulating effective road safety measures. Pedestrian exposure can be a useful explanatory variable for modeling crashes but this piece of information is often difficult and costly to collect. The study attempts to take advantage of time geography and travel activity data to propose a new pedestrian exposure metric. Making use of the concept of potential path tree (PPT), this paper developed an individual-based and network constrained pedestrian exposure measure. Using negative binomial regressions to examine crash frequency with exposure, roadway and environmental variables, the proposed metric is compared with other existing pedestrian exposure methods to examine its applicability and potential in road safety analysis.