Mixed fleet dispatching in truckload relay network design optimization

• A descriptive model for mixed fleet dispatching for TL carriers is proposed.
• Point to point movements and transport through a relay network are permitted.
• Difficult operational constraints are modeled and large instances are solved.
• Combining relayed and direct shipments outperforms traditional dispatching method.
• For high fixed cost of installation, mixed fleet outperforms a pure relay network.

We propose a mathematical formulation for strategic relay network design and dispatching method selection for full truckload transportation. The proposed model minimizes total transportation and installation costs of a mixed fleet dispatching system combining relay network and point-to-point dispatching. Operational constraints such as maximum driver tour length and load circuity are considered within the variable definition using predefined templates to generate feasible routes. High quality solutions for largely-sized problem instances are obtained in reasonable times. Computational results are analyzed to develop insights about the mixed fleet dispatching system and quantify its benefits over relay network-only and point-to-point dispatching.