Optimizing Sustainable Relay Freight Transport Networks: A Case Study in Japan

Abstract

Relay transport networks design plays an important role in improving logistics efficiency, involving the determination of the number of relay points, costs of constructing these points, and constraints on the distance between relay points. The configuration of these unique characteristics must consider multiple aspects of sustainability, including economic, environmental, and social factors. In this study, we aim to determine the optimal relay network configurations and transportation routes through a multiobjective optimization model, considering three key objectives: maximizing freight demand for relay transport, minimizing total costs, and maximizing CO₂ emission reduction. The proposed model was solved using the Gurobi optimization solver. A case study conducted in Japan revealed that the optimal relay network configuration consists of 23 relay points, including 21 small, 1 medium, and 1 large point. This optimized configuration yielded three significant contributions for environmental, economic, and social aspects, namely 34.72% reduction in CO₂ emissions, 3.65% reduction in transportation costs, 27.47% reduction in overtime for short-haul trips, and 14.92% reduction in overnight stays for long-haul trips. Our findings recommend the following policies: (i) trucking companies should set the distance constraints between two adjacent relay points as 150 km for short-haul trips and 450 km for long-haul trips to balance environmental, social, and economic priorities; (ii) the Japanese government’s proposed budget (2.5 billion yen) for relay point construction is relatively sufficient, exceeding our estimated construction cost (2.095 billion yen); and (iii) relay transport implemented as a standalone measure has the potential to help achieve the Japanese trucking industry’s CO₂ emission reduction target.