Network-Based Walk-Access Coverage of an Integrated Metro–Bus System: Measurement Sensitivity and Distributional Outcomes in Riyadh

Abstract

Walk access determines the effective catchment of a transit system, yet coverage statistics are still commonly derived from straight-line buffers, and no network-based estimate exists for Riyadh’s newly integrated metro and bus system. This study quantifies walk-access service coverage for the Riyadh urban center along the pedestrian network, tests its sensitivity to measurement choices, and examines who is served. Using open data, network access distances were computed by shortest-path search; coverage was evaluated across network scenarios and thresholds; the pedestrian route directness ratio isolated the effect of street layout; and Lorenz curves, Gini coefficients and spatial econometric models characterized the distribution of supply. Under conventional thresholds, 24.2% of residents live within walking distance of an operational stop or station—or 19.6–30.4%, depending on the definition of the operating bus network—against 42.7% from straight-line buffers. The metro alone serves 7.8%; most coverage comes from feeder and community bus routes. More than three-quarters of residents cannot reach any line, while supply among those served is comparatively even. Coverage rises with building height, residential density and proximity to arterial corridors, is robust to spatial error and lag models, and is not detectably associated with district land price. Coverage gains are therefore expected from feeder routes and pedestrian permeability rather than trunk expansion, al-though these measures were not modeled. The results give planners a baseline for tracking route openings and support reproducible monitoring of Sustainable Development Goal (SDG) indicator 11.2.1 in Riyadh and comparable cities.