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Rail Engineer • March 2015
London Bridge final layout (2018) showing segregated traffic flow Southeastern South central – resignalled 05/01/15 Thameslink
Bermonsey Dive-under Borough Viaduct
London Bridge final layout (2018) showing segregated traffic flow. Alas rail privatisation, planning and funding issues have seriously delayed the scheme. The solution is a simple one - provide a segregated two-track route throughout between Blackfriars and Bermondsey for exclusive use of Thameslink trains, thereby removing the various conflicts. Implementation of this segment of the overall Thameslink programme has, however, involved significant multi-function, highly complex and costly engineering works consisting principally of a new two-track viaduct at Borough Market, a diveunder at Bermondsey, extensive track remodelling, total resignalling, and rebuilding the station to create three additional through platforms.
Enabling works The footbridge linking the high and low level platforms carried signalling cables linking the ASC to track functions on the Down side of the line and to Cannon Street and Charing Cross. As this bridge was to be demolished as part of the rebuilding, a new cable route was created by drilling down underneath the ASC and utilising the space within the arches that support the railway track above, thereby regaining the existing cable routes on the down side. This also required the provision of a new 11kV substation within the arch to re-feed ASC. The work of rebuilding the terminal (low level) platforms, which was concluded during the recent blockade, has been progressing since 2013. Initially, the three highestnumbered platforms were taken out of service for rebuilding, followed in turn by the other platforms, leaving six in service at any one time. This work has necessitated some alterations to the track layout in the throat. The signal interlocking alterations were accomplished by modifying the existing geographical relay interlockings and also building a temporary rack consisting of a dozen or so
London Bridge Station reconstructed
refurbished Westpac units, some of which were displaced from the initial platform closure works. The final configuration is of six terminal platforms (10-15), instead of the original nine, thereby creating space for additional through platforms. The indication panels of the ASC are original, apart from complete replacement of the troublesome filament bulbs with maintenancefree LEDs, done about a decade ago, and replacement of the cathode ray tube train describer (TD) displays with LED equivalents. The original GEC-GS TD was replaced many years ago with a Vaughan system. As the latter is now also obsolete, and train descriptions are a vital information system for signallers and railway operations in general, the project team decided to de-risk this functionality by installing a new Siemens TD system at the outset of the current project. Unlike the indication panels, signalling thousands of train movements over the years has taken its toll on the separate signallers’ consoles. Accordingly, a maintenance project to replace the faceplates, buttons and switches was undertaken by control panel specialist TEW Engineering Ltd of Nottingham over the last
Westcad workstation cubicle with ETCS.
To East Croydon / Brighton
few years. As TEW has been on site during the resignalling work, it made sense to incorporate the alterations to both indication panels and control desks as the stagework layout changes progressed. A week after the big blockade shut Platforms 8 and 9, Platforms 5 and 6 were also taken out of use as the work of rebuilding the through platforms got under way, facilitating an increase from six to nine (1-9).
National Operating Strategy (NOS) As described in issue 120 (October 2014), Network Rail’s NOS envisages that all signalling control will be achieved through twelve Rail Operating Centres. Control of the whole of the London Bridge ASC area will migrate to the Thameslink ‘POD’ (a rectangular enclosure of ten desks) at Three Bridges ROC. The former south central ASC area transferred there on 5 January and consists of two identical workstations with two signallers working to an agreed protocol, replicating the entrance-exit route setting and point movement functionality of the ASC, albeit with keyboard and mouse replacing buttons and switches.