Railway Interlocking Process: A Formal Method for Documenting and Evaluating Railway Junction Signalling and Interlocking

Abstract

Railway junctions have been signalled in many different ways using various railway interlocking and signalling technologies. Implementations of those technologies are not identical and are customised for every railway junction. It is therefore very difficult to consistently compare various signalling and interlocking technologies using currently available methods. That creates an enormous task for transport and/or signalling planners to propose the technology that meets the operational conditions on a specific railway junction. This thesis enhances the signalling and interlocking planning process by developing a formal method for documenting and evaluating railway junction signalling and interlocking. More precisely, it makes the following contributions: • it develops a structured method to enable railway transport planners to evident a specific railway junction arrangement and, in response to it, determine and describe a corresponding signalling and interlocking algorithm. This includes characterisation of: o manual interlocking algorithm o mechanical interlocking algorithm o electrically powered interlocking algorithm. • it develops an analytical model to calculate the railway junction’s interlocking and signalling requirements determined by the track arrangement installed, such as: o minimum travel distance o maximum velocity o minimum train travel time in the track arrangement. • it defines performance measures relevant in the railway interlocking evaluation process, such as interlocking processing time, signalling system cost, interlocking functionality, signalling system availability and reliability. These operational performance measures allow consistent comparison and evaluation of the interlocking on a railway junction.