The topology of a network has unique characteristics that signify the network’s levels of performance and productivity through transport efficiency which reflects the connectivity among its nodes (stations or waypoints). Efficiency can be quantified for unweighted networks where links (rail lines) and nodes are assumed to have equal significance and therefore assigned equal weights. However, realistic transport rail networks have links and nodes that present differing impacts and attributes. Each of the nodal or link attributes are assigned varying weights resulting in distinct efficiency values. Unweighted networks might be simpler with regards to efficiency analysis, but weighted networks provide more authenticity and accuracy in representing existing rail conditions. Analyses of weighted networks show that weights have a direct but varying impact on network efficiency.&nbsp;To demonstrate the robustness of the proposed methodology, the following weighted attributes were considered:·&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Distance·&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Track class 0 to 8·&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Track quality·&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Direction of travel·&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Type of signaling·&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Type of traffic·&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Traffic tonnage·&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Travel time·&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Power·&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Economic value of freight or passenger traffic·&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Traffic flow and frequency·&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Passenger volume·&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Maintenance·&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Reliability·&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Proximity to critical infrastructure·&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Weather factors&nbsp;Some attributes are related to links, such as, distance, travel time, and track quality while others are related to nodes, such as, location node degree, location significance, and closeness centrality. Using a unified scale for weights is beneficial given that attributes have different measurement units and scales; these attributes’ treatment requires methods to accommodate one or more weight factor for each node or link. Assessing network efficiency is typically based on a single attribute and sometimes concurrently based on more than one attribute. Therefore, methods to normalize weights as a means to unify their scales for aggregation and calculations are needed and presented.&nbsp;Examining the efficiency based on network topology with and without weights offers a basis to assess performance, capability, productivity, resilience, etc. with respect to different attributes&nbsp; in separate or aggregate terms. A network can be efficient with respect to one attribute, but inefficient with respect to another attribute. Quantifiable and objective insights gained into the criticality of links and nodes inform rail planners and mangers of their best options for maintaining and improving the overall transport efficiency of their networks.

Weights and Their Consideration in Topological Analysis of Rail Networks

Paper Proceedings: https://asmedigitalcollection.asme.org/JRC/JRC2021/volume/84775

2021 Joint Rail Conference (JRC2021)

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