Evaluating transport improvements in spatial equilibrium

The recent development of quantitative urban models provides a new set of tools for evaluating transport improvements. Conventional cost-benefit analyses are typically undertaken in partial equilibrium. In contrast, quantitative urban models characterize the spatial distribution of economic activity within cities in general equilibrium. We compare evaluations of a transport improvement using conventional cost-benefit analysis, sufficient statistics approaches based on changes in market access, and model-based counterfactuals. We show that quantitative urban models predict a reorganization of economic activity within cities in response to a transport improvement, which can lead to substantial differences between the predictions of these three approaches for large changes in transport costs.