Simulation-Based Multistage Optimization Model for Railroad Alignment Design and Operations

In railroads, the vertical alignment design is closely related to the cost of operation because it may affect the required energy consumptions. By considering an innovative vertical alignment design concept such as the dipped vertical alignment (DVA) profile, the required energy consumptions, namely, tractive energy and braking energy, may be reduced. As a result, the cost of train operations may be reduced. In addition, the cruising speed and coasting operations are important operational decisions. Thus, this paper proposes a multistage decision model to jointly optimize the vertical alignment profile, cruising speed, and coasting operation point. The minimum cost solution is obtained considering the costs of users and operators. A deterministic simulation model is incorporated to calculate the vehicle motion, dynamics, resistance, and other computation outputs. A case study followed by sensitivity analyses are presented to discuss how the input values (e.g., unit energy cost, passenger's time value) affect the operational decisions (i.e., cruising speed or coasting operation).