A spatiotemporal disparity of transit and automobile access gap and its impact on transit use

This research empirically evaluates the access gap between transit and automobile to examine the extent of auto-access-orientation within and between the 50 American Metropolitan Areas. The Modal Access Gap (MAG) index is calculated over space and travel time to test three hypotheses: (1) MAG is a function of space and travel time, (2) MAG is CBD-centric, and (3) MAG is associated with transit use. Results indicate that (1) MAG merely possesses negative values ranging between −0.98 and −0.79, regardless of the travel-time thresholds or metropolitan areas, and the travel time lag between transit and automobile ranges from 35 minutes in New York to 51 minutes in Riverside for a 60-minute commute, (2) MAG decreases as one moves away from the central area, and (3) a 1% increase in MAG increases transit use by 1.37% on average.