An Optimal Integrated Real-time Disruption Control Model for Rail Transit Systems
Rail transit systems are subject to frequent minor disruptions caused by random disturbances. Although these minor disruptions usually last no longer than 10-20 minutes, they can degrade the level of service significantly on a short headway service. This
- PDF / 3,411,501 Bytes
- 29 Pages / 439.37 x 666.14 pts Page_size
- 79 Downloads / 191 Views
Abstract . Rail transit systems are subject to frequent minor disruptions caused by random disturbances. Although these minor disruptions usually last no longer than 10-20 minutes, they can degrade the level of service significantly on a short headway service. This paper describes an integrated real-time disruption control model, formulated as a mixed integer program , for rail transit syst ems, which includes holding, expressing and short-turning strategies. Although the model is capable of dealing with multi-branch systems, the model was applied to a disruption scenario on a single line system as a first ste p. Two cases with 10 and 20 minute disruption duration are tested. The results showed that holding strategies combined with short-turning strategies reduced the mean passenger waiting time by 35% in the former case and 57% in the latter case, compared with not applying any cont rol strategies. Expressing provided only modest additional benefits . Sensitivity analysis was used to investigate the impact of the deterministic disruption duration assumption. The results showed that holding and expressing solutions were fairly robust, but the effectiveness of short-turning solutions was quite sensitive to the accuracy of the disruption duration estimate. In one scenario, the passenger waiting time increased by 14% under an est imat e 50% less than the actual disruption duration, compared with the result with correct estimate. Problem instances without expressing can be solved in less than 30 seconds of computation time with the branch-and-bound algorithm proposed to solve this mixed int eger problem.
1
Introduction
Minor disruptions lasting up to 10-20 minutes occur frequently in rail transit systems due to random disturbances such as medical emergencies, car problems or signal malfunctions. To reduce the impact of thes e disruptions on passengers, transit agencies often employ real-time control strategies such as holding, expressing and short turning. In th e holding strategy, trains ahead or downstream of the disruption are held after normal passenger boarding and alighting, and , th erefore, the long headways created by the disruption can be reduced and the capacity of the held trains may be used to reduce the crowding on trains behind or upstream of th e disruption. In the expressing strategy, trains behind the disruption may skip a few stations after the S. Voß et al. (eds.), Computer-Aided Scheduling of Public Transport © Springer-Verlag Berlin Heidelberg 2001
336
Shen and Wilson
disruption is cleared. Hence, long headways ahead of the express trains are reduced. If a disruption is serious , the first few trains may be full after pieking up passengers right after the disruption clearance. It may make sense to express these trains to avoid unnecessary delays and reduce passenger waiting time beyond the express segment. In the short-turning strategy, trains are short-turned from the reverse direction into the blocked direction ahead of the disruption. Short-turning can significantly reduce long headways.
Data Loading...
