Transfreight's MIP balanced crossdock workload and cut costs on Toyota Kentucky inbound

Transfreight is a third-party logistics provider that runs inbound supply for Toyota Motor Manufacturing in North America, operating crossdocks where trailers are unloaded and their freight is quickly transferred to outbound trucks in line with Toyota's lean manufacturing system. At a crossdock, freight dwell time is minutes, so the assignment of inbound trailers to dock doors directly determines how smoothly workers are loaded through a shift.

Working with Transfreight, researchers built a mixed-integer linear program that optimally allocates inbound trailers to dock doors, with improving operational efficiency and balancing the workload of crossdock workers as explicit objectives. The model was implemented at Transfreight's largest crossdock, in Georgetown, Kentucky, for its inbound trailer assignments.

Why it works: the door decision couples freight flow with labor effort. Leaving it to dispatchers optimizes each trailer locally while workload concentrates wherever freight happens to arrive. Optimizing all door assignments at once spreads the work, which on a lean dock is the difference between smooth flow and queues, and the paper reports significant cost savings plus growth headroom for Transfreight.

Assign trailers to doors with a MIP, balance the workload

Door assignments couple freight flow with labor effort, so optimizing them jointly balances work that manual rules leave lumpy.

Toyota's lean inbound system punishes uneven dock throughput, making workload balance a first-class objective rather than a nicety.

Transfreight ran several crossdocks for Toyota, so a validated model at Georgetown could spread to the rest of the network.

Door choices look like floor-level calls, but together they are one assignment problem - solve it centrally and the workload balances itself.

The paper reports a successful implementation for inbound trailer assignments at the Georgetown, Kentucky crossdock, Transfreight's largest, and states that the work provided significant cost savings and growth opportunities. The model gave Transfreight a repeatable way to absorb more Toyota volume through the same facility.