Freight Transit Assignments for an Integrated Network of Road Transportation and Underground Logistics Systems

Abstract

Alleviating the pressure due to increasing freight transportation traffic by using low-emission and innovative transportation methods can reduce a number of problems, such as transportation network capacity limits and environmental pollution, and contribute to the development of resource-efficient and sustainable cities in the future. An underground logistics system (ULS) can improve the service quality and transportation efficiency of urban logistics and alleviate traffic congestion and associated problems, such as energy consumption and air pollution. Previous studies on urban ULS have primarily focused on technical feasibility and policy requirements, whereas analyses of the effects of introducing ULS on the existing transportation network are scarce. The main goal of the present research is to develop a method of freight transit assignment for an integrated transportation network of aboveground roads and the main line and branch lines of the ULS. A formulation for an integrated transportation problem of freight for roads and ULS was established along with a process that considers the loading, unloading, and transfer of freight among each mode. Based on the random utility theory method, a stochastic assignment model was used to divert freight from the road to the ULS using a network that possesses critical transport features, including multiple freight demands and alternative transit routes. The influence of several factors, such as travel speed, departure frequency, and the capacity limitations of lines and nodes, was analyzed, and the results showed that the ULS was the preferred mode of freight transportation. Freight transportation via ULS is more efficient than road transportation, which provides a foundation for further investigation into the integration of ULS in road transportation networks in aboveground and underground spaces.