Each of today's 25 private operators in the U.K. pays Railtrack whenever one of its trains rolls along a line. Although this is much simpler in terms of accounting, companies must make extremely efficient use of the lines to earn a profit. In analyzing their profit potential, and the associated need to increase ridership, the train-operating companies and the British government's Office of the Rail Regulator determined that operators must provide travelers with more general information about railroad services. Before giving up their cars, passengers want convenient train schedules and connection information. They need to understand ticketing options, and, most importantly, they need a simple, reliable method to determine when the next train is to arrive at their station.
Many alternative methods exist to predict the physical location of any train.
We made a thorough review of the more-feasible options before we selected our methodology. The system uses powerful mainframe computers located in Crewe and Nottingham to monitor the movement of every train in Britain. It collates stored train schedules with real-time performance updates obtained from trackside reporting points. The principal drawback is that the system is accurate only when the trains adhere to their time-tables. The corrections provided by the reporting points had limited value for the ScotRail project as the stations are often too far apart to give frequent enough status information.