Abstract:In practice, vehicle scheduling is planned on a variable timetable so that the departure times of trips can be shifted in tolerable ranges, rather than on a fixed timetable, to decrease the required fleet size. This paper investigates the vehicle scheduling problem on a variable timetable with the constraint that each vehicle can perform limited trips. Since the connection-based model is difficult to solve by optimization software for a medium-scale or large-scale instance, a designed path-based model is devel… Show more
“…A. This approach has been applied to other integrated problems in transportation, such as aircraft routing and crew scheduling problem [20], and vehicle scheduling based on a variable timetable problem [21]. For more literature about this approach, we refer the reader to Mercier et al [22], Restrepo et al [23], and Lee and Han [24].…”
As the core of the rail freight flow organization process, train formation problem (TFP) has attracted much attention. In Chinese practice, car flow routing, TFP, and train routing are usually optimized sequentially to reduce the complexity of computation, which may result in a local optimum, and even no feasible solution. To address this issue, this paper studies the integrated optimization of the three sub problems with aims to minimize the total cost of transportation cost, accumulation cost, and classification cost. An integer linear arc-based model incorporating the unitary and in-tree rules of a shipment is first formulated and solved by the state-of-the-art solver GUROBI. Since GUROBI can't deal with the large test cases, a path-based model is built and solved by a bespoken two-phase algorithm. The first phase of the algorithm is Benders-and-Price approach that combines Benders decomposition and column generation, and the second phase is to solve the arc-based model with some variables fixed as the corresponding values fetched from the first phase. The results show that the proposed algorithm outperforms GUROBI, and the acceleration techniques, i.e., trust region and Pareto-optimal cuts, can improve the convergence efficiency of Benders decomposition significantly.INDEX TERMS Train formation problem, car flow routing, train routing, benders decomposition, column generation.
“…A. This approach has been applied to other integrated problems in transportation, such as aircraft routing and crew scheduling problem [20], and vehicle scheduling based on a variable timetable problem [21]. For more literature about this approach, we refer the reader to Mercier et al [22], Restrepo et al [23], and Lee and Han [24].…”
As the core of the rail freight flow organization process, train formation problem (TFP) has attracted much attention. In Chinese practice, car flow routing, TFP, and train routing are usually optimized sequentially to reduce the complexity of computation, which may result in a local optimum, and even no feasible solution. To address this issue, this paper studies the integrated optimization of the three sub problems with aims to minimize the total cost of transportation cost, accumulation cost, and classification cost. An integer linear arc-based model incorporating the unitary and in-tree rules of a shipment is first formulated and solved by the state-of-the-art solver GUROBI. Since GUROBI can't deal with the large test cases, a path-based model is built and solved by a bespoken two-phase algorithm. The first phase of the algorithm is Benders-and-Price approach that combines Benders decomposition and column generation, and the second phase is to solve the arc-based model with some variables fixed as the corresponding values fetched from the first phase. The results show that the proposed algorithm outperforms GUROBI, and the acceleration techniques, i.e., trust region and Pareto-optimal cuts, can improve the convergence efficiency of Benders decomposition significantly.INDEX TERMS Train formation problem, car flow routing, train routing, benders decomposition, column generation.
“…Standard models and solution approaches for vehicle scheduling in public transport are summarized in Bunte and Kliewer (2009). Recent vehicle scheduling approaches usually incorporate problem specific aspects such as variable timetables (Desfontaines and Desaulniers 2018;Lan et al 2019) or limited range of electric vehicles and recharging strategies (Wen et al 2016;Rogge et al 2018). To be able to find good schedules for realistic instances, elaborate solution methods are proposed.…”
Section: Vehicle Schedulingmentioning
confidence: 99%
“…To be able to find good schedules for realistic instances, elaborate solution methods are proposed. For example, Desfontaines and Desaulniers (2018) rely on column generation, and Lan et al (2019) combine Benders decomposition with a branch-and-price approach. With these methods, instances with up to 2100 vehicle trips could be solved within less than 1 h to optimality or close to optimality.…”
The planning of on-demand services requires the formation of vehicle schedules consisting of service trips and empty trips. This paper presents an algorithm for building vehicle schedules that uses time-dependent demand matrices (= service trips) as input and determines time-dependent empty trip matrices and the number of required vehicles as a result. The presented approach is intended for long-term, strategic transport planning. For this purpose, it provides planners with an estimate of vehicle fleet size and distance travelled by on-demand services. The algorithm can be applied to integer and non-integer demand matrices and is therefore particularly suitable for macroscopic travel demand models. Two case studies illustrate potential applications of the algorithm and feature that on-demand services can be considered in macroscopic travel demand models.
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