An approach to improve the operational stability of a bus line by adjusting bus speeds on the dedicated bus lanes

Bus bunching and the unevenly dispersed buses along a bus line commonly appear in an unstable high-frequency bus line system. They will lead to unreliable transit service and long waiting times for many passengers. To resist bus bunching and improve the stability of a bus line, researchers proposed some methods of adjusting the cruising speeds of buses. But their methods generally need to adjust the speeds in all road segments included in the bus line and sometimes need to coordinate the speeds of successively cruising buses. These requirements impede their implementations in practice. This paper presents a new strategy to overcome the above obstacles by adjusting the speeds of buses in the dedicated bus lanes. The regulating speed will be determined by looking multiple critical time points ahead to estimate the influence of the chosen speed. Numerical experiments show that the new strategy can not only stabilize a strongly unstable bus line but also shorten the waiting and riding times of passengers. Several insights have also been uncovered during numerical analyses. a. The set of regulating speeds used by an effective speed adjustment strategy should include refined elements and has a wide range for the values of its elements. b. Only with nonnegative elements in the above set, the strategy will be out of work. c. The more dedicated bus lanes in a bus line, the more effective the strategy becomes. The negligible computational time to supply the proper regulating speed makes the implementation of our strategy practical