  Bus bunching and unevenly dispersed buses along a bus line lead to a low
service level and deteriorate the operational stability of the bus line. Speed
adjustment as a control means has been proposed to solve the above problem. But
due to the difficulty of adjusting speed in the mixed traffic and the
discontinuously distributed dedicated bus lanes (DBLs) in a bus line, the
existing methods which coordinate or adjust bus speeds in all road segments
encounter serious obstacles in practice. To overcome the above problem, we
first take into account the influence of the deployment of the DBLs along a bus
line on the performance of the speed adjustment strategy. With the funding
limit and the maximally allowable influence on other road traffic as main
constraints, a nonlinear mixed integer stochastic mathematic model is
formulated aiming at improving the whole stability of the bus line operation.
The model can be effectively solved by a newly designed branch and bound
algorithm. The optimal regulating speed in a DBL is determined with a process
of looking multiple critical time point ahead. Numerical experiment verified
the effectiveness and efficiency of our new method. Three findings were
obtained as follows. To determine the optimal regulating speed, the number of
the critical time points to be looked ahead should not be too big. Increasing
the number of DBLs improves the stability of a bus line. The more evenly DBLs
are distributed along the bus line, the greater the stability of the bus line
will be.
