OPTIBUS: A Scheduling Package

Abstract

Any transit process planning includes four basic components performed in sequence: (1) network route design; (2) setting timetables; (3) scheduling vehicles to trips; and (4) assignment of drivers. It is desirable for all components to be planned simultaneously to exploit the system’s capability to the greatest extent and to maximize the systems’s productivity and efficiency. However, this planning process is extremely cumbersome and complex, with the outcome of one fed as an input to the next component. The overview of this planning process is shown in Figure 1 with an emphasis on the three scheduling components to be adressed in this paper. The second component in Figure 1 is aimed to meet the general public transportation demand. The demand varies during the hours of the day, of the week, from one season to another and even from one year to another. This demand reflects the business, industrial, cultural, educational, social and recreational transportation needs of the community. It is the purpose of this component to set appropriate timetables for each transit route to meet the variation in the public demand. Determination of timetables is performed on the basis of passenger counts and must comply with service frequency constraints.

The transit scheduling system called OPTIBUS is comparised of three interrelated modules; (a) a timetable design module which constructs alternative computerized public timetables based on procedures which bring bus departure times in line with passenger demand; (b) a vehicle scheduling module which minimizes the number of vehicles required to carry out a fixed timetables or alternatively minimizes the total dead-heading kilometers for given number of vehicles: (c) a crew scheduling module which determines a feasible set of driver duties.

This paper gives a overview of the OPTIBUS scheduling system, as well as experience accumulated in the last three years while implementing OPTIBUS in several transit companies in Europe. The paper also describes a unique interactive full graphical optimization which leads in one implemention to save about 5 % of the operational cost.