Toward Efficient Transportation Electrification of Heavy-Duty Trucks: Joint Scheduling of Truck Routing and Charging

The timely transportation of goods to customers is an essential component of economic activities. However, heavy-duty diesel trucks that deliver goods contribute significantly to greenhouse gas emissions within many large metropolitan areas, including Los Angeles, New York, and San Francisco. To facilitate freight electrification, this paper proposes joint routing and charging (JRC) scheduling for electric trucks. The objective of the associated optimization problem is to minimize the cost of transportation, charging, and tardiness. As a result of a large number of combinations of road segments, electric trucks can take a large number of combinations of possible charging decisions and charging duration as well. The resulting mixed-integer linear programming problem (MILP) is extremely challenging because of the combinatorial complexity even in the deterministic case. Therefore, a Level-Based Surrogate Lagrangian Relaxation method is employed to decompose and coordinate the overall problem into truck subproblems that are significantly less complex. In the coordination aspect, each truck subproblem is solved independently of other subproblems based on charging cost, tardiness, and the values of Lagrangian multipliers. In addition to serving as a means of guiding and coordinating trucks, multipliers can also serve as a basis for transparent and explanatory decision-making by trucks. Testing results demonstrate that even small instances cannot be solved using the over-the-shelf solver CPLEX after several days of solving. The new method, on the other hand, can obtain near-optimal solutions within a few minutes for small cases, and within 30 minutes for large ones. Furthermore, it has been demonstrated that as battery capacity increases, the total cost decreases significantly; moreover, as the charging power increases, the number of trucks required decreases as well.