Simulating the effects of higher speed passenger trains in single track freight networks

North American freight railroads are expected to experience increasing capacity constraints across their networks. To help plan for this increased traffic, railroads use simulation software to analyze the benefits of capacity expansion projects. Delay increases exponentially with volume as individual lines and the network become more saturated with traffic. Simultaneous operation of heterogeneous traffic further increases delay relative to additional homogenous traffic. Running higher speed passenger trains with higher priorities amplifies heterogeneity. Rail Traffic Controller (RTC) was used to run simulations with varying mixes of unit freight and passenger trains operating at various speeds ranging from 50 to 110 mph. Additional passenger trains delay freight trains more than additional freight trains will. Higher speed trains also introduce more variation to the delay. These analyses will help planners improve their understanding of the tradeoff in capacity due to operation of trains at different priorities and speeds.