Effects of urban road capacity expansions – Experiences from two Norwegian cases

Abstract

This article presents nuanced and context-related empirical research on the traffic-inducing effects of urban road capacity expansion two Norwegian cities. It focusses on the indirect and longterm land-use effects and on land-use planning and policies, that are not well covered in existing literature. Unsurprisingly, results show traffic-inducing land-use development in the period after the road capacity expansions. Differences in planning policy and practices affected how traffic inducing the land-use development was. The traffic growth was stronger in the affected road corridors than expected, and as compared with Norway. No or only short-term congestion relief was found. It is concluded that the road capacity expansions were necessary conditions for the land-use sprawl, and consequently, contributing causes for the traffic growth. Ex-ante analyses seem not to have included the land-use effects, and this is understood as part of the explanation for the discrepancies between ex-ante expectations and actual development. In both cases, municipal and regional authorities currently attempt to steer land use development in directions contributing to stop traffic growth, in accordance with national policies. Meanwhile, road authorities plan for new capacity expansions in the investigated corridors. Land use effects of the capacity expansions seem, again, not to be included in the assessments.