All ridership is local: Accessibility, competition, and stop-level determinants of daily bus boardings in Portland, Oregon

Research on accessibility, a measure of ease of reaching potential opportunities, has advanced significantly, but the adoption of these measures by public transport agencies has lagged. One explanation may be that research has been conducted at different spatial scales from the stop level typically used by agencies. To address this gap, this study examines the relationship between accessibility to jobs and average daily bus boardings at the bus-stop level of analysis in Portland, Oregon. Our models show that daily boardings could increase by 1.8% to 2.1% for every 10% increase in accessibility, measured as the number of jobs reachable in 30 min from the bus stop by public transport. This finding supports the argument that accessibility-focused service improvements have the potential to bolster stop-level ridership since network adjustments and new services like bus-rapid-transit often yield considerable increases in accessibility. At the same time, inter-stop competition reduces an individual stop's ridership. This study conveys the benefits of planning for accessibility at a regional scale and links regional decisions back to stop-level ridership, the context most familiar to public transport agencies, in the hope that this will accelerate and extend the adoption of accessibility in practice.