Abstract
Link capacity reductions, which occur often, degrade the service quality and performance of urban rail transit (URT) networks. To measure the reliability of a URT network when link capacity reductions occur in a given time period, the passengers’ generalized travel cost (GTC) is computed and passengers are divided into three categories. The GTC considers here the crowding in trains, seat availability, and perceived travel time. Passengers whose relative increase in GTC on a URT is below or above a preset threshold belong to category I or II, respectively, while passengers who cannot travel on the URT due to insufficient capacities on their paths belong to category III. Passenger trips in categories I are acceptable since their GTC increases only slightly with link capacity reductions. The fraction of acceptable trip (FAT) and total GTC increase ratio (TGCR) in a given time period are defined here as the network’s reliability and unreliability metrics, respectively. The ratio of affected passenger trip (RAPT) is proposed to identify each line’s most critical links. The reliability and unreliability metrics of Wuhan’s URT network during evening peak hours are computed when the capacities of the most critical link or multiple most critical links are reduced. The results show that the proposed RAPT indicator is effective in identifying the most critical links that greatly affect the reliability and performance of a URT network. For capacity reductions on a line’s most critical link, the proposed method can determine the capacity reduction ratio corresponding to network’s high FAT and low TGCR as well as the priorities of lines needing emergency measures to maintain high network reliability and performance. For capacity reductions on critical links of multiple lines, the proposed method can identify the number of reduction links and the capacity reduction ratio that the network can withstand while maintaining its reliability and performance above a specified level.
Highlights
To deal with the urban challenges of congestion, noise, and emissions due to rising demand, urban rail transit (URT) development is promoted by China’s government for its desirable economic, social, and environmental benefits [1]
Equation (6) can be applied to computed passengers’ total generalized travel cost (GTC) C(Eredu, x) when capacities of link set Eredu are reduced by x. e total GTC increase ratio (TGCR) is defined as the metric of the unreliability of a URT network when capacities of link set Eredu are reduced by x, which is computed with the following equation: Run
Where Ie is the ratio of affected passenger trips who is affected by link e, which is computed based on a logit-based stochastic user equilibrium model
Summary
To deal with the urban challenges of congestion, noise, and emissions due to rising demand, urban rail transit (URT) development is promoted by China’s government for its desirable economic, social, and environmental benefits [1]. E vulnerability of the transport network was measured based on network performance with and without complete failures at stations or links. The passengers’ travel behavior and transport capacity were neglected in some studies when measuring the vulnerability, reliability, resilience, and robustness of URT networks. Considering traffic demand and transportation supply could measure the influence of full and partial link capacity reductions on network performance, which helped to measure the reliability, vulnerability, and robustness of transportation networks. If link capacity reductions occur, the reliability of the URT network decreases because some passengers’ perceived service quality is not acceptable. Passengers in category I perceive acceptable service when link capacity reductions occur, since their GTC increases only slightly. E total GTC increase ratio (TGCR) is defined as the metric of the unreliability of a URT network when link capacity reductions occur. The proposed indicators and method are applied to Wuhan’s URT network during evening peak hours. e reliability of Wuhan’s URT network during evening peak hours is computed when the capacities of each line’s most critical link or multiple lines’ most critical links are reduced. e proposed indicators and method help to identify each line’s most critical links, as well as the extent and the relations among the capacity reductions on lines’ most critical link and network performance, thereby supporting infrastructure management and capacity allocation
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
