Urban Sprawl and Public Transport: A Quantitative Spatial Model for a Railway Policy in Budapest

Abstract

Investing in suburban public transport is often promoted to encourage mode shift and mitigate the negative impacts of car use. However, improved suburban access may unintentionally drive suburbanization and urban sprawl, introducing unexpected externalities. This study examines these counteracting effects using a spatial computable general equilibrium model calibrated as a quantitative spatial model. The method is applied to a proposed railway tunnel under the Danube in Budapest. Results show an increase in public transport use along the railway, alleviating road congestion in the city center. While no strong evidence of urban sprawl emerges, the model reveals that reduced car congestion may prompt some inner-city residents to revert to car use. These findings suggest that investments in suburban public transport should be paired with traffic calming measures to prevent offsetting behavioral responses and maximize the policy’s effectiveness.