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Open Access Publications from the University of California

Dynamic Control of Complex Transit Systems


This paper proposes a dynamic control method to overcome bunching and improve the regularity of fixed-route transit systems. The method uses a combination of dynamic holding and en-route driver guidance to achieve its objectives. It applies to systems with a mix of headway-based and schedule-based lines but it is evaluated for scheduled systems as this is the more challenging application. Improved schedule adherence is the goal. The method’s calculation complexity per piece of advice does not increase with system size. As a result, the method is scalable and can be used with large multiline systems, no matter how complex. When controled, each vehicle is mostly affected by exogenous disturbances (e.g. traffic) and very little by other vehicles. As a result, disruptions to a vehicle or group of vehicles caused by inattentive drivers or control equipment failures remain confined to the vehicles experiencing the problems. The control method effectively quarantines “disease”. The method is evaluated analytically and with simulations over a broad range of conditions, including schedules with zero slack. The method was also evaluated by observing the performance of a real world multi-line system that uses inexpensive on-board tablets to apply the control. The evaluation addresses driver compliance and equipment malfunction issues. It is found that the method is resilient and improves reliability considerably even under challenging conditions.

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