Measuring the Value of Time in Highway Freight Transportation
This research investigated several aspects of the value of time (VOT) in the trucking industry. This included examining the marginal monetary benefits and costs of reduced and prolonged freight transportation time on highways.
First, a comprehensive survey estimated truckers? perceived VOT by combining stated preference, utility theory, conditional logit modeling, and maximum likelihood function. From the data collected around major cities in Texas and Wisconsin, the truckers? perceived VOT was estimated to be $54.98/vehicle/hour. Second, scenario-based simulation examined urban truckload operations, the purpose of which was to examine the fleet effect of individual vehicle delay on the carrier?s operation. Two of the most congested highway segments in Houston were used for the simulation, together with constrained delivery windows. The result showed that the scenario-based vehicle VOT varied from $79.81/vehicle/hour to $120.89/vehicle/hour. Third, VOT based on commodity delay only was examined in relationship to inventory management by assuming prolonged transportation time or freight delay. Delay of chemical products was ranked as the highest VOT at $13.89/truckload/hour, followed by food products at $7.24/truckload/hour. Finally, a continuous approximation technique was developed for fleet operations in the context of less-than-truckload deliveries. The trade-offs between travel time and roadway transportation cost were derived analytically and results were used to estimate fleet value of time. Ignoring time windows, the vehicle VOT for major distribution companies in Texas was estimated to be $15.50/vehicle/hour for highway trips and $22.00/vehicle/hour for local trips.
To summarize, freight VOT is not only directly due to vehicles and drivers, but depends on fleet operations and supply chain management. The several approaches adopted in this research represent possible perspectives that need to be further examined. They each reveal a component of the entire shipping process that can be appropriately utilized to calculate the overall freight VOT in future studies. For example, an urgent delivery carrying chemical products can be estimated at a total congestion cost of $162.86/vehicle/hour. However, trips with different characteristics need to be treated individually andcarefully to avoid overestimation. It remains challenging tocombineall these different elements adequately to reach valid VOT for the trucking industry.