Impact of Operational Practices on Rail Line Capacity: A Simulation Analysis

Long-term demand for freight and passenger rail traffic in North America is expected to expand increasingly leading to capacity constraints. Both infrastructure investment and operational changes can relieve congestion. However, given the high cost to build and maintain infrastructure, careful consideration of how operational practices can affect or mitigate demand is critical for cost-effective planning of new capacity. A key aspect of this is the effect of heterogeneous traffic characteristics on capacity. Different freight and passenger trains have substantially different operating characteristics including: speed, acceleration, braking and dispatching priorities. Greater heterogeneity on a line increases interference between trains and creates more delays than if all trains have similar characteristics. Train dispatching simulation software was used to analyze the impact of heterogeneity under a range of realistic infrastructure configurations and operational conditions. Analyses were conducted to evaluate the effectiveness of various operational changes to reduce delays. The trade-off between reduced congestion and increased cost was considered for each change. A benefit of operational changes is that they can be more rapidly implemented and offer greater flexibility than capital infrastructure investments if future traffic patterns change.