How accessibility perception can improve accessibility measurement

The concept of perceived accessibility (PA) provides a way of capturing individual disparities in the context of the spatial analysis of travel behaviors. However, the measurement of perceived accessibility raises certain issues. Based on the standard gravity-based accessibility indicator, we propose a theoretical analysis for estimating perceived accessibility. We take account of individual heterogeneity by considering the differences between individuals' perceptions of travel time. We capture this perception through individual travel cost sensitivity and an enhanced impedance parameter. We test our method on urban data from the Household Transport Survey (HTS) conducted in Lyon (France) which permits disaggregated spatial analysis. This survey uses 4-stage model calibration and provides transport data that takes account of the socioeconomic characteristics of more than 11,000 households. A comparison between measurements of standard gravity-based accessibility and perceived accessibility confirms that there is a difference between the two, with lower results for PA than the standard accessibility indicator. Our results also reveal that measured PA is highly dependent on the spatial zone: in the CBD, which has a relatively wealthy population, travel sensitivity is lower than in suburban spatial zones. Therefore, a transport policy change impacting accessibility can have beneficial spatial impacts.