The Economic Value of Reserve Capacity Considering the Reliability and Robustness of a Rail Transit Network

Existing studies estimate the economic value (EcV) of network reliability and robustness separately. In this study, a model is proposed for estimating the EcV of reserve capacity in a rail transit network (RTN), which consists of: (1) the reduction of passengers' total generalized travel cost (GTC) in normal operations, (2) the EcV of reliability enhancement in normal operations, and (3) the EcV of robustness enhancement when disturbances occur. The standard deviation of travel time (SDT) is used to measure travel time reliability (TTR). The reserve capacity helps to reduce passengers' total GTC and the SDT during normal operations. The EcV of reliability enhancement equals the EcV converted from the reduction in SDT when the RTN operates normally. The EcV of robustness enhancement is the difference of passengers' total GTC with and without reserve capacity when disturbances occur. To optimize reserve capacity, a model is developed to maximize its net benefit, equaling its EcV minus its cost, which is then solved with a quantum genetic algorithm. A case study of Chengdu's RTN shows the effectiveness of the model with promising numerical results. The research findings show that the value of reserve capacity is severely underestimated without considering the EcV of reliability and robustness. The study can guide policymakers and operators in quantifying the EcV of reliability and robustness enhancement when expanding an RTN's capacity.

Automated summary

This study proposes a model for estimating the economic value (EcV) of reserve capacity in a rail transit network (RTN), considering the reduction in passengers' total generalized travel cost and the enhancements in reliability and robustness. The model is optimized using a quantum genetic algorithm and is validated through a case study of Chengdu's RTN. The findings highlight the significant underestimation of the value of reserve capacity when the EcV of reliability and robustness is not considered, providing guidance for policymakers and operators in evaluating the EcV of capacity expansion in an RTN.