The Impact of Switch Faults on Train Delays: A Case Study of the Swedish Railway Network

Switches and crossings are prone to failure thus making them drivers of unreliability in the operation of many railway systems. Unreliability is directly linked to punctuality which continues to limit, among other factors, the uptake of railways as a sustainable mode of transport. To fix this issue, there is a need for a better understanding of the contribution of railway sub-systems to train delays. Therefore, this paper seeks to quantify the impact of switch faults (switch failures and switch inspection warnings) on the delay of a train, using historical train operation and maintenance data. We have investigated the increased chance of a train being delayed in the event of a switch fault and the average size of delay that can be attributed to a switch fault. We find that 1) in the event of a switch failure trains have a 1% increased chance of experiencing a dwell delay, a 0.7% increased chance of experiencing an arrival delay, and a 0.1% increased chance of experiencing a departure delay for non-stopping trains; 2) the impact of switch inspection warnings on train delays is negligible; and 3) on average, a train is delayed by six extra minutes in the event of a switch failure. This study serves as a step towards quantifying primary delays and their origin in the railway system. Understanding the sources serves the purpose of informing decision-makers on the areas for prioritization during operations planning. Understanding the source and magnitude of primary delays is also important for simulation.