Influence of track arrangement on expanding rail corridor capacity and operations

The North American freight railroad network is projected to experience rising freight transportation demand in the coming decades, coupled with continued interest in expanding passenger services. Congestion resulting from these demands strains the capacity of rail lines and jeopardizes the operational fluidity of the rail network, particularly along shared rail corridors. While track construction is just one of many alternatives a railroad may employ in expanding practical capacity (and thereby boosting throughput), this practice represents substantial capital investment. With the purpose of helping rail practitioners better utilize their resources, this thesis aims to investigate track expansion alternatives in detail, ultimately providing an improved understanding of the link between track arrangement, train delay, and line capacity. The majority of mainline rail corridors in North America consist predominantly of single track with passing sidings or short sections of double track. These track arrangements lack the flexibility to reliably handle high traffic volumes composed of multiple types of trains. Increasing frequency of long freight-train operations also magnifies capacity constraints posed by inadequate, short sidings. This work explores the capacity benefits of siding expansion to meet these developing operational needs, leading to a discussion of the incremental capacity in transitioning from single to double and triple track, both from a quantitative and qualitative perspective. Experiment designs are carried out in Rail Traffic Controller simulation software to reveal fundamental relationships between track arrangement and other capacity factors via statistical analysis of the results. While railroads must consider many factors in selecting capital expansion projects, the trends identified through this research can help streamline the planning process by helping industry practitioners quickly identify track expansion project alternatives with the greatest potential capacity benefit for more detailed engineering evaluation