The Kent Coast electrification of the late 1950s was all about eliminating steam traction and only partial modernisation of signalling on the North Kent line route was undertaken.
New signal boxes were commissioned at Rochester, Rainham, Sittingbourne and Faversham, 30 boxes were abolished and the remaining boxes were adapted for the new electrified railway.
Colour light signals were installed all the way to Ramsgate, but the boxes on the Dover line retained mechanical lever frames and semaphore signals. Four-tracking was provided between Rainham and Newington but, elsewhere, the layouts were largely unchanged.
Whilst other elements were modernised piecemeal in subsequent years, new cabling and much of the telecoms, the signalling has remained essentially the same until now. Being well over 50 years old, something had to be done.
The East Kent Resignalling Project
Designed to be commissioned in three phases with many intermediate stages, the project centres on the new East Kent Signalling Centre (EKSC) located at Gillingham. Constructed in the style of Upminster, Derby and Didcot, this is the shape of Signalling Control Centres for the future. Equipped initially with only 2 control workstations, the centre is big enough to accommodate 12 desks as its area of operation expands.
Phase 1, which was commissioned over the Christmas 2011 period, covers the area from east of Sittingbourne to Minster Junction and Buckland Junction just short of Dover Priory.
Fringe boxes are at Sittingbourne, Minster and Folkestone East. Extensive track remodelling has taken place at Ramsgate (both the Minster and Dumpton Park ends of the station) and Faversham with plain lining being done at Whitstable, Herne Bay, Birchington and Canterbury East.
Old signal boxes have been abolished at Faversham, Margate, Ramsgate, Canterbury East and Shepherdswell. Canterbury East box, built high on a cantilevered girder, is in a conservation area, so how to use this to best advantage in the future is open to debate. Similarly, Ramsgate box is listed
Later phases of the project will extend the new signalling westwards from Sittingbourne to fringe with the Victoria Power Box west of the Medway towns and on from Minster to link up to the Ashford box boundary. Contracts for these sections have still to be let.
The Signalling System and Equipment
Phase 1 of the project comprises 332 SEUs (Signalling Equivalent Units), the modern day methodology for sizing a signalling area. The heart of the scheme is the SmartLock computer-based interlocking installed at EKSC and divided into seven VIXLs (Virtual Interlockings) to cover the extent of the resignalled area. SmartLock is one of the new generation of Solid State Interlockings (SSI) with more processing capacity and much reduced size compared to earlier designs of SSI.
The EKSC workstations are entirely screen based with no conventional signalling mimic diagram. This is a modern version of the Integrated Electronic Control Centre (IECC) designed originally in the 1990s. Setting of routes is mostly automatic from timetable and train describer source data but the signallers can use a tracker ball if changes to the planned schedule are required.
In addition to the signalling control screens, additional VDUs give access to the SPT network, the Cab Secure Radio system and telephone / mobile contact to stations, control offices, electrification controls, TOC offices and both the internal and external telephone networks.
Trackside, new signals of the LED type have been provided throughout, these being a mixture of 3 and 4 aspect according to traffic needs. Headways have been improved to give a maximum of 6 minutes on the lighter used routes.
A flashing yellow is provided on the down line at Faversham to give advance warning when trains are diverging towards Ramsgate. Points are operated using HW2000 point motors supplied by Invensys, known to be robust and reliable machines.
Except for the station areas at Faversham and Ramsgate where TI21 track circuits are used, the whole area has been converted to axle counters using the standard Thales product.
In all, there are 254 axle counter sections. Track circuits remain in the two areas named because this is where trains can split and join. Experience has shown that the toing and froing movement whilst this happens can cause axle counter mis-reads, which must be avoided if reliable working is to be achieved.
Six level crossings exist on the resignalled routes of which five are AHBs that remain essentially unchanged except for the indications being transferred to EKSC. The sixth crossing, at Teynham, was a manned gate crossing but this has been converted to a CCTV controlled full barrier crossing controlled from EKSC.
On telecoms, new SPTs have been provided at every main line signal but point zone telephones have been eliminated reflecting the increased use of mobile telephones by maintenance staff. Dial up telephones are hosted off Chatham exchange, this being able to accommodate the short code dialling (17x) to access the electrification control rooms.
Key to all of these has been the availability of the Network Rail FTN (Fixed Telecom Network). This nationwide fibre and digital transmission network, with its almost limitless bandwidth and dual routing capability, was always intended to be used as a control and command distribution system for all branches of rail engineering.
Thus the SmartLock, level crossing, SPT, radio and general purpose telecom communication requirements are all borne upon the FTN. Constructed in ring topology, any break in the fibre cable is immediately detected and the digital signals are automatically diverted via another route.
The Project and Contractual Structure
Network Rail chose to use its now well tried hub and spoke model for project control. The Network Rail project team form the hub and directly control all the supply and installation contractors as the spokes. Contracts have been let on a fixed price basis but allowing variations for any re-measureable work. The principal contract base consists of:
Signalling Solutions Ltd (SSL) – the Alstom Balfour Beatty joint venture company to deliver signalling projects, including the signalling system design and data preparation, the provision of the SmartLock interlocking equipment at EKSC, the provision and onsite installation of 372 lineside equipment cases, 10 REBs, 254 axle counter sections, 118 track circuits, 195 new signals, all AWS /TPWS units, plus the level crossing equipment provision at Teynham and the re-control of the AHBs.
SSL carried out the test and commissioning of the signalling equipment and also all the signalling work needed to accommodate the stageworks and fringe box alterations;
Buckingham Construction Group – nominated as principal contractor, they undertook all external construction works including cable routes, cabling, signal post erection and recoveries, building foundations, signal box demolition and level crossing conversion;
GE Transportation Systems (GETS) – the EKSC control centre system and equipment including the control console screens;
Siemens – telecommunications work but with a sub contract to Northgate for the provision of the SPT switch (based upon an Ericsson MD110) and to Demovo for the SPT touch screens;
Balfour Beatty – track remodelling including switch and crossing work;
Network Rail Internal Maintainer – Point conversions.
The Cab Secure Radio (CSR) terminals for EKSC have been provided from spare units held by the Network Rail telecom team who designed and adapted the terminals for their new environment. After commissioning, the redundant CSR terminals in the 5 closed boxes have been returned to store for future maintenance spares. The CSR control areas have been reduced from 5 to 2 and, following a desk top exercise by Thales, 3 of the 19 base stations giving radio coverage to the lines have been recovered.
Provision of trackside power has required a new power cable throughout. This has been designed as a mixture of 3 phase and single phase. SSL undertook the power system design and supply for the whole area, with the support of IUS as a subcontractor, for the provision of 10 new supply points, the upgrade of two substations and high voltage work at EKSC.
Since the majority of the route is now equipped with axle counters, impedance bonds have been removed except in the remaining track circuited areas. Signal testing was undertaken by SSL. Reviewing the Test Plans produced by the SSL Tester in Charge was overseen by the Network Rail Testing and Commissioning Manager.
A significant problem during installation has been cable theft. This menace, that is rampant in all parts of the world, has had to be combated by improved security at depot sites and increased vigilance at the trackside.
Phase 1 has consisted of 24 track stages, the last one being the Christmas commissioning, with earlier stageworks having to be done utilising weekend abnormal possessions. A good record of safety has been achieved with no major accidents or injuries
The Christmas 2011 Work
A total possession for the entire project area was taken at 00.05 on Christmas Day morning. There were 13 parts to the possession, including extensions to the limits so as to permit fringe changeovers. This allowed optimisation of testing and consequent shortening of possession time so as to give back access to the TOC and enabling services to be resumed over the commissioned sections.
The gods were with the team since the weather was very favourable for the time of year. The changeover went according to plan and handback occurred in three elements:
04.00 on 28 December from Sittingbourne to clear of Ramsgate station but including Ramsgate depot, allowing the TOC access to the depot for train maintenance purposes;
04.00 on 29 December from Faversham to Buckland Junction, thus permitting a service to operate to Dover and beyond;
01.00 on 3 January from Ramsgate station to Minster.
Whilst there were some inevitable minor glitches during the commissioning period, the co-operation between the various parties was commendable and emerging problems were quickly resolved. Special mention must be made of the relationship between Network Rail and Southeastern.
This has been first class with established mutual trust in place. Regular monthly meetings had been held for several years preceding the commissioning and ad hoc ones at other times. Southeastern produced an illustrative booklet for briefing drivers that detailed what was to be done, which in itself has received much commendation. No significant delay minutes have been incurred as a result of the project.
A big bonus for the TOC is that Ramsgate depot movements can now be carried out without impacting on the main line and equally any main line isolation of the traction power supply does not impact on the depot
Early planning works for Phase 2 are underway and currently within GRIP Stage 3. Future Phases are in the early stages of development. These will convert the remaining lines in East Kent not yet controlled by an existing power box. Such is the flexibility of modern signalling systems that the contractor supply base will be tendered competitively.
The basic specification will remain unchanged but it is likely that obstacle detectors will be introduced at level crossings if trials elsewhere are successful.
Thanks are expressed to Bruce Kirkpatrick, Keith White and Steve Gausden from the Network Rail project team for willingly sharing their experiences and for their enthusiasm and commitment to making the project a success, also to Maria Griffin from SSL for detailing the scope of the signalling contract and Simon Walkley of Buckingham Group for his comments on the civils side.