The US rail network includes shared corridors that feature both freight and passenger train operations. The reliability of these mainline links is critical to ensuring that freight supply chains meet the level of service demanded by industrial customers while also providing performance that meets the mobility needs of commuters and the traveling public. Satisfying both of these rail transport objectives promotes economic development and supports job creation. However, the differing characteristics and performance requirements of freight and passenger trains create numerous operational challenges that impact the reliability of both operations. Optimizing the
level of capital investment in track infrastructure and train control system required to meet the desired reliability of a shared corridor is critical to the economics of these operations.
Previous researchers have used simulation to document the capacity (throughput) and performance (delay) implications of differences in passenger and freight train speed, power, weight, length and priority. Most critically, the capacity consumed by a single train varies across train types, and corridors with increasing levels of train heterogeneity require correspondingly more infrastructure to achieve the same performance and reliability as heterogenous freight-only or passenger-only corridors. However, a key limitation of existing research is that, during the 10 to 15 years since it has been conducted, freight railroads have altered their operations considerably, shifting to widespread deployment of longer trains, relying on locomotive assignments with lower horsepower-per-ton, and reconstructing corridors with longer passing
sidings or stretches of two main tracks in place of single track with frequent short sidings. In addition, the relative priority or dispatching preference given to passenger and freight trains has been raised as a critical issue, but was not explored in previous work. Thus, there is a critical need to update existing relationships to reflect this new operational paradigm.
To quantify the reliability of shared corridors under modern railway operating strategies, the project team will review past relationships and develop appropriate simulation experimental designs incorporating new factor levels to specifically capture important operational changes such as long trains and assigned priority. Using an accepted railway simulation tool, factorial combinations of these factors will be simulated, and results subjected to appropriate statistical analyses to examine changes in Base Train Equivalents over time and between operating conditions. The resulting freight and passenger train performance relationships will be evaluated via case studies to illustrate modern trends in shared corridor reliability.