An intermodal freight optimization and routing model: Balancing cost, emissions, and time in multimodal network design

Intermodal freight is promoted as a pathway to lower emissions, but trucking dominates in practice due to accessibility limits, transfer costs, and infrastructure gaps. Existing models reinforce this imbalance by prioritizing transport costs and underrepresenting emissions, time, and facility design. To address these gaps, we introduce the Intermodal Freight Optimization and Routing Model (INFORM), a mixed-integer quadratic program that jointly minimizes cost, time, and emissions while incorporating fuel technologies, candidate facility siting, directional waterway speeds, and up to two intermodal transfers per shipment. Applied to the St. Louis–Louisiana corridor, INFORM identifies trucking as optimal under nominal conditions, minimizing the combined economic measure of costs, emissions, and transit time. Break-even analysis shows that rail and barge would only compete at line-haul distances far beyond those available, as access, egress, and transfer penalties outweigh their per-mile efficiency advantages. Under facility disruptions, flows remain truck-exclusive, with rerouting along highways preferred over modal shifts. Forcing new facilities reduces delivery times but raises costs and emissions, underscoring the importance of placement and demand density. Sensitivity analysis finds diesel truck operating costs dominate system performance under the tested parameter perturbations, while transfer frictions remain important in the break-even conditions governing marginal modal switching. Intermodal investments remain valuable, but only when paired with measures that directly address trucking’s structural advantage.