A Rolling Stock Circulation Model for Railway Rapid Transit Systems

Rolling stock is one of the key operational issues for a railway transportation company. In fact, rolling stock and infrastructure maintenance suppose about 75% of total cost for a typical railway network. Rolling stock circulation consists of defining individual train paths over the network accomplishing pre-defined passenger's services and fulfilling certain design criteria such as minimizing train costs. The maintenance of the train is an important aspect to be considered in the planning of rolling stock circulation. Typically, railway operators follow maintenance policies in which rolling stock must be revised every certain number of kilometers.In this paper we propose, in the context of railway Rapid Transit Systems (RTS), a mixed integer programming model to develop rolling stock circulation plans considering a rotating maintenance scheme. The model can be applied to any medium size RTS considering a variable number of parking facilities. Train circulation is obtained by following a weekly pattern to include weekend train schedules. This approach minimizes train empty movements whereas equilibrates the weekly number of kilometers covered by every train unit. The rotating schema ensures a long-term maintenance policy that minimizes the train units reserve and balances the workload of the maintenance operation. Finally, as illustration, the modeling approach is applied to the Seville commuter railway network in order to design a rotating rolling stock plan.