The External Congestion Costs of Differential Vehicle Sizes

Because Light-Duty Trucks (LDTs) are heavier, longer, wider, and higher than passenger cars, they reduce the maximum service flow of traffic. The US Highway Capacity Manual does not account for this. This paper uses generally accepted functions for travel time and the marginal social cost of a trip with registration data to calculate the cost of trips with and without LDTs in traffic. We compute a differentiated toll to internalise the differential vehicle size externality. We also find that the presence of LDTs leads to an additional cost of travel time between $206 and $674 per mile for each hour of congested traffic. © 2012 LSE and the University of Bath