Assessment of U.S. chassis supply models on drayage productivity and air emissions

Abstract

A new drayage scheduling model is developed to assess the effectiveness of different U.S. chassis supply models. It extends previous drayage models by incorporating these features: (1) treating tractor, container, and chassis as separate resources which are provided in different locations, (2) ensuring that container and chassis are of the same size and type, and (3) considering the possibility that drayage companies can subcontract the work to independent owner-operators whose trucks will originate from and terminate at different locations. The resulting model is a mixed-integer quadratic programming model that solves the scheduling of tractor, loaded container, empty container and chassis in drayage operation in an integrated manner. The mathematical model is an extension of the multiple traveling salesman problem with time windows (m-TSPTW). To efficiently solve the developed model, a reactive tabu search (RTS) algorithm combined with an insertion heuristic is developed. The model and algorithm are used to evaluate the effectiveness of different chassis supply models currently in use in the U.S. The results indicated that among the U.S. chassis models the co-op pool, terminal pool and rental pool with chassis yard inside the terminal yield the lowest drayage operation time, percentage of empty movements, and air emissions.