An Operating Strategy for a Commuter Bus System

The operator of a bus system wishes to determine when and where to send each vehicle in order to minimize the sum of operating and user costs incurred in carrying commuters from a central terminal to destinations dispersed over the city and its suburbs. Application of a continuum approximation approach to this problem leads to an objective function which is a function of one unknown variable, the zone size. Analytic solutions are obtained for a number of special cases. If the problem parameters do not vary with the time of day, the optimal zone size for suburban locations is inversely proportional to the square root of the density of passenger destinations if the vehicles are filled to capacity, but to the cube root if they are not completely filled. A numerical example of this special case is used to illustrate a technique for application of the results.