Contextualising the impact of street slopes on pedestrian accessibility for sustainable mobility

Source abstract

Proximity-based planning has become a central paradigm in transport policy, guiding the design of sustainable, accessible, and liveable cities. This shift has driven the development of various methods for assessing pedestrian accessibility, reflecting the central role of walking as the most sustainable mode. Yet, the impact of street slopes on accessibility is often neglected and remains poorly understood. This study identifies two systematic biases: a slope-speed bias, caused by assuming flat terrain, and a slope-preference bias, reflecting behavioural aversion to slopes. We compare three models: (a) slope-agnostic, (b) slope-adjusted with gradient-dependent speeds, and (c) slope-preference incorporating walking preferences across walking propensity groups. Applied in Athens, Greece, results show that slope-agnostic models overestimate accessibility by approximately 6–8% on average. Accounting for walking preferences introduces an additional 33–40% reduction for low-propensity walkers across destination types. The proposed framework offers a transferable approach for integrating terrain sensitivity into accessibility analysis.