Effects of Road and Other Mode Supply on Car Use

Abstract

This paper estimates how changes in road supply, non-car mode supply, and destination density affect individuals’ vehicle kilometres travelled (VKT). Using population-wide Swedish register panel data for 1998, 2005, and 2017 matched to historically reconstructed transport networks and simulated generalized travel times, we construct logsum-based accessibility measures by mode. Methodologically, we combine long-horizon first-difference models with an instrumental-variable strategy based on accessibility changes around the initial residential zone to address spatial sorting and time-varying endogeneity. We show that pooled cross-sectional models substantially overstate behavioural responses relative to first-difference and IV estimates. The most robust result is a modest reduction in VKT from improvements in non-car accessibility, while direct effects of road supply and density become small once sorting is accounted for. Improved non-car accessibility modestly reduces VKT: a one-standard-deviation increase in relative accessibility lowers car use by 1–3.5%.