Timetable Reliability Study
Client: Chiltern Railways, Dec 1998
After route modernisation in the late 1980s, Chiltern Railways' services had become renowned for the high levels of service performance, which continued through the railway privatisation process. However, 1997 and 1998 saw a deterioration in performance which did not recover when key issues (such as engine replacement, and doubling of the line between Bicester and Princes Risborough) were attended to. Indeed, the performance of the service in Autumn 1998 fell so much that management decided to implement timetable changes as soon as possible, in an attempt to improve matters.
The Railway Consultancy Ltd were therefore called in at short notice to provide an independent analysis of the proposed timetable, including an estimate of the likely impact on the punctuality statistics recorded for Passengers' Charter purposes. In the time available, it was not possible to construct a computer simulation, so a manual exercise was carried out. This included surveying a number of trains, to ascertain whether realistic running times were being allowed. Analysis of turnrounds at Marylebone and other service reversing points was conducted both from the viewpoint of rolling stock utilisation and track occupation. A spreadsheet-based service flexibility model was used to assess what proportion of the problems being encountered were due to the timetable itself, and what proportion to infrastructure issues. Specific incidents were analysed in both the current and future timetables, in order to see what impact the changes would have on peak period right time arrivals. Recommendations were made in respect of further adjustments to the timetable.
* Further work was carried out in 2002 using our Trakattk™ software to assess the operability of different timetable and infrastructure options under 'Project Evergreen' which aims to develop the line.
Last updated: Sunday, 18th December 2016
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