Energy savings in mixed rail traffic rescheduling: an RCG approach

This paper presents an enhanced version of the Resource Conflict Graph (RCG) approach for railway rescheduling that considers the reduction of tractive energy consumption in the rescheduling process. The objectives and constraints considered in freight train rescheduling are different from those related to passenger trains. For example, there is generally more flexibility in freight train scheduling regarding routes and departure/arrival times. On the other hand, freight trains have frequent unplanned stops for overtaking and acceleration phases use significant energy, especially for long freight trains. Therefore, energy consumption is recognized as an important cost factor in freight train operations and it is commonly used to help plan schedules. Energy consumption can be reduced by choosing energy efficient paths (less traffic, less gradient) and driving with speed profiles that improve route regularity (i.e., that avoid unplanned stops and minimize acceleration phases). The paper describes the proposed rescheduling approach and then applies it in a numerical example evaluated using the test track of the Railway Operations Lab located in the facilities of the Institute for Transport Planning and Systems (IVT) at ETH Zurich.