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Rail Engineer • March 2015
Automatic Route Setting (ARS) was removed from the scope to avoid rework when the full Traffic Management (TM) requirements become available. TM introduces the train graph interface and it is likely that drop-down menus will be the norm for route and point setting. Within TM, automatic route setting is performed by Immediate Route Setting (IRS) rather than ARS. It may seem strange that what is ostensibly part of the Kent route should be installed in the Sussex ROC. However, the strategic importance of the Thameslink spine, including the Brighton main line, favours control from a single ROC. Although the newly segregated routes through London Bridge are reflected in the configuration of signallers’ workstations, there are several crossovers that will allow trains to cross from one domain to the other in the event of engineering works or disruption. Setting routes between, say, the Charing Cross and Thameslink corridors will require an initiation and acceptance process by the respective signallers who, sitting within the same POD, will be able to swing around in their chairs and discuss issues face-to-face. The Thameslink core workstations within Victoria and West Hampstead signal boxes are scheduled to migrate into the POD this month. Similarly, the London Bridge ASC south-eastern area is due to be resignalled or recontrolled and handed over to the POD by 2018. In due course Three Bridges ROC will also take over control of the routes currently signalled by the existing Three Bridges and Victoria ASCs. A training suite is provided at Three Bridges for signallers using the TREsim control and operations simulation software for Westcad supplied by TRE of Wiltshire, a Hitachi Group Company. TREsim was also used earlier in the project by Network Rail to demonstrate the 2018 segregated traffic flows to key stakeholders.
New signalling kit The workstations are of the Siemens Controlguide Westcad PC-based control and display system. Totally-independent and diversely-routed duplicated fibre optic Data Comms Networks, DCN(A) and DCN(B), utilise the Fixed Telecom Network (FTN) and, using Cadlock protocol, link the Westcad at the ROC with the Westlock interlockings located at the London Bridge equipment room built within the arches. DCN is the forerunner for IP-based systems. The flexibility of the data communications facilitates re-scaling or relocation of workstations in the event of a major issue. Of course, the level of security provision of ROCs and the new equipment rooms is commensurate with the business criticality. The first of five Siemens Trackguard Westlock interlockings was commissioned on 5 January, covering the south central area. The principle
Stagework Westpac MKIV 'GO-I' signal unit.
of segregated routes also applies to the signal interlockings. Still to be commissioned are Cannon Street, Thameslink, Charing Cross and Hither Green. Westlock has a much greater capacity than SSI, hence only one Westlock is required to replace the four SSIs at Hither Green. This also obviates the tricky design issues associated with SSI boundaries. The new south-central Westlock communicates with Track Function Modules (TFMs) conventionally using two base-band data links and three with Long Distance Terminals (LDTs). The five data links are separately interfaced with Westlock via a Trackside Interface (TIF) which acts as a protocol converter between the Westlock network communications and SSI data links. However, it is envisaged that a Siemens object controller system will deploy zone controllers instead of TFMs, with IP addressing used for communication rather than SSI data link protocol. Existing remote relay interlockings at Forest Hill, Old Kent Road and Peckham Rye have been re-controlled to the ROC using Siemens Westronic 1024 via a Westcad Signalling Interface (SIF). The existing FDM system in the recontrolled areas was also replaced by new Westplex systems. Bombardier EBITrack 400 track circuits are used for train detection with Cembre rail terminations. EBITrack 400 is the next generation digital version of the TI21 family for use in DC or AC electrified areas. Axle counters were not considered suitable for use in a layout with many short sections, reversible working and a variety of train length configurations, not to mention performance issues associated with reset procedures. Unipart Dorman integrated lightweight signals (iLS) are used. They have a threedegree narrow beam well suited to the multiple parallel tracks on the approaches to London Bridge where SPADs have occurred
in the past through misreading or readingthrough. In-bearer clamp-lock point operating mechanisms are used. Signalling power supplies are 650V DC dual-end-fed with auto reconfiguration, Class II. In addition to the London Bridge equipment room, 34 relocatable equipment buildings (REB) will house much of the lineside equipment for the complete scheme, 10 of which were commissioned over Christmas. Due to the limited space, clearances and access issues on the Victorian viaducts upon which the trains run, the REBs are mostly contained within the arches. This provides a much better environment for faulting and maintenance staff, limiting exposure to both the running lines and the elements. As well as 11 new signal gantries, for which planning consents have had to be obtained, some existing gantries have been re-used, where appropriate, for the scheme and refurbished with improved access for staff. The project, in conjunction with Cemex, has developed the innovative EG53 and GV54 cable management sleepers which have now become a national ‘favourite’, enabling both DC traction and signalling cables to cross the track without cluttering up the ballast cribs and removing the risk of tampers damaging cables.
Welcome back Thameslink Come 2018, the principal of segregated traffic flows of the 1970s resignalling will be restored. Thameslink, once perceived as an unwelcome interloper disrupting the flow of traffic through the station area, will be providing a new highquality and capacity service fit for the twentyfirst century. Thanks to Network Rail’s Simon Pears, Andy Hatton, Gary Murphy and Roy Bell for their help in the preparation of this article.