Scheduling of bus maintenance by the P-graph methodology

The P-graph (process graph) framework is applied herein for the bus maintenance planning in the public transport system. Public transportation is an essential part of the life of each major city. A number of logistic tasks have to be handled day by day in order to ensure uninterrupted operation. Malfunctions can result in additional cost, delays, discomfort, and bad reputation. Undisturbed operation requires solving both scheduling and planning optimization problems. One of these problems is the planning of the regular maintenance tasks which are mostly carried out in the night shift at our industrial partner. If maintenance is not planed properly then not enough buses are available for service. A P-graph based model has been developed for such a maintenance scheduling problem which is capable to take into account not only the night period but the whole day including the usually unused time of the buses during daytime. The appropriate scheduling of maintenance is especially important if the average age of the buses is high and thus the break downs are common. It is highly difficult to ensure the required number of serviceable buses for each morning shift without proper maintenance scheduling. Using the proposed systematic method, a better maintenance schedule can be developed where certain repair tasks can occur between the morning and afternoon rush hours. This will reduce the cost as repairs at night are more expensive.