Greedy algorithm for railway traffic re-scheduling during disturbances: a Swedish case

The positive trend of increased use of railway transportation in Europe has resulted in an increased sensitivity to and occurrence of traffic disturbances. The kernel of the disturbance management problem is to revise the original timetable in line with the new conditions and decide where, when, and how trains should overtake or meet to minimise the negative effect of the disturbance. In previous research, the author has designed optimisation-based approach for rescheduling, which seems promising but for some scenarios it is difficult to find good solutions within seconds. Therefore, the author developed a greedy algorithm that effectively delivers good solutions within the permitted time. To quickly retrieve a feasible solution, the algorithm performs a depth-first search using an evaluation function to prioritise when conflicts arise and then branches according to a set of criteria. A performance analysis of the algorithm was carried out using simulated experiments showing its strengths and weaknesses.