Multimodal Transport Networks

Over half of distance-weighted U.S. freight is shipped using more than one transport mode.We examine how multimodal transport networks shape the economic and environmental impacts of infrastructure investments and disruptions.We develop a tractable spatial equilibrium model of multimodal routing with mode-specific congestion at intermodal terminals.We estimate a modal substitution elasticity using road and rail data, and a terminal congestion elasticity using vesselpositioning data.Calibrated to the U.S. freight network, the model identifies key bottlenecks and quantifies $.46-$1.85 billion in real GDP gains from intermodal terminal improvements, with additional environmental benefits from shifting away from carbon-intensive road transport.Ignoring mode-specific congestion overstates welfare gains from highway improvements by 85%, while ignoring multimodal flexibility understates them by 22%.Losing rail network access is estimated to reduce real GDP by $230 billion.