Maintenance and overhaul scheduling of transportation assets

We consider a fleet of a number of deteriorating transportation assets. Deterioration of each asset is defined by the conditions of critical components within an asset. These components are replaced once they deteriorate up to a safety limit before the asset is renewed. Human resource constraints dictate that overhaul actions can only be performed on one asset at a time. Hence, different ordering of overhaul activities on the assets would affect the total maintenance costs of the system. In this paper, "the assignment problem" is used to model the ordering of overhaul activities. The Hungarian algorithm is then be implemented to find the optimal order which minimise the total maintenance costs of the system. In order to demonstrate industrial practicability of this approach, a case study is conducted in a train maintenance setting. Here, we look at brake system maintenance of a fleet of trains whose deterioration is defined by its brake disc wear. These discs are replaced once they wear up to their safety limit until the whole train is overhauled. An optimal order of the overhaul actions are determined by solving the assignment problem. Results show that such method can help reduce the total maintenance costs of the system compared to the current method of coming up with an order based on individual brake disc wear of each train