Yoshinori Suzuki

Dept: Supply Chain and Information Systems

Keywords: Transportation, trucking industry, vehicle routing problem

I view myself as a transportation specialist, as I have focused on conducting research only in the transportation industry, especially in the trucking industry, throughout my career.  Two of my recent research areas (problems addressed) are described below.

The first is the vehicle-refueling problem.  After fuel prices increased dramatically since 2008, many researchers have started to consider this problem, which seeks to find the optimal (cost minimizing) set of refueling points (gas stations or truck stops) for a given vehicle.  My first work showed that the fixed-route vehicle-refueling problem (FRVRP), the most basic form of the vehicle-refueling problem, can be formulated as a mixed-integer linear program meaning that the optimal solution can be obtained by using the simplex algorithm (before this paper was published all studies treated the FRVRP as a complex problem, for which a special solution technique must be developed).  Most of my other work has considered extensions of the basic problem form, in which both the vehicle-refueling problem and the vehicle-routing problem are solved jointly, and proposed solution techniques for these problems (exact and heuristic algorithms).  My most recent work in this area proposed a cutting-plane technique for various versions of the vehicle-refueling problem. I showed that by using this technique the solution (CPU) time can be reduced dramatically, especially for large instances.

The second is the pollution routing problem (PRP).  This is a variant of the classic vehicle-routing problem (VRP), which seeks to minimize the fuel consumption of a fleet of vehicles.  My initial work was among the first ones to propose a mathematical formulation of the PRP.  This paper also showed, by conducting simulation experiments, that the optimal routes under this new formulation (that minimize fuel consumption) are notably different from those under the classic VRP formulation (that minimize travel distance or time).  In the second paper I proposed a simple, yet effective, heuristic that is designed specifically for small motor carriers (who typically do not have technical personnel) to solve the PRP.  Given that the majority of motor carriers are small in many countries (e.g., 87% of U.S. motor carriers operate 6 or fewer trucks), developing a simple PRP technique that can be used conveniently by small carriers is quite meaningful from the standpoint of reducing trucks’ total carbon footprints.  In the third paper I developed a hybrid metaheuristic method that generates high-quality PRP solutions.  Computational testing with standard test instances showed that this method compares very favorably with the benchmark methods available in the literature, obtaining best-known results in many instances.

Email: ysuzuki at iastate.edu, Phone: 4-5577