Signalling goes undercover

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In her delicious north-east accent, the elderly lady waiting for her train at Seaham exclaimed, “Oh, a’ve ernly just nerticed tha’ signal’s gone.” She was referring to the prominent cantilevered semaphore that had graced the end of the Up platform. Such has been the nature of the second of four proposed phases to resignal the entire Durham Coast line – purposely low key. The work has gone quietly ahead and before anyone had seemingly noticed, this state-of-the-art signalling scheme was in use.

Commissioned on Monday 15th November and covering 16 route miles of double-track railway from Stranton near Hartlepool to Ryhope Grange, south of Sunderland, this £28 million project has been undertaken with Invensys Rail as principal contractor. The signalling and telecoms work, which started in May 2009, has been completed on time and within budget. It has significantly increased line capacity on the secondary route linking Newcastle with Middlesbrough via Sunderland, Hartlepool and Stockton.

The first phase of the scheme – a £3.7 million contract awarded to Jarvis Rail and covering the section from Greatham to Cliff House – was commissioned back in July 2007. A remote relay interlocking located near Seaton Carew was interfaced via a Westronic S2 system to a new panel within Greatham signal box. This allowed the closure of Cliff House box.

Completion of the latest phase has resulted in the closure of five more – Stranton and Clarence Road at Hartlepool, Dawdon, Seaham and Hall Dene. All were of North Eastern Railway origin, dating from the early 1900s. Control has been transferred to a new interlocking located at the existing Ryhope Grange signal box near Sunderland. The former box at Seaham has however been retained as a gate box to oversee a busy footpath crossing, although plans are in place to replace this with a footbridge in 2011. A third signal box at Hartlepool, Cemetery North, had been abolished in December 2008 following an arson attack.

Technical overview

The main contractor, Invensys Rail, already had a zero-value framework agreement in place with Network Rail, but won the Durham Coast resignalling contract through competitive tendering. Initial design work (GRIP 1-4) was initiated in 2004 by Network Rail, but Invensys undertook the detailed design work. Thales was appointed as its main subcontractor for telecoms whilst VolkerFitzpatrick took on a similar role for the civil engineering.

The signalling scheme was based around Invensys Rail’s Westlock computer-based interlocking system. An entirely new telecoms network would also be installed, making use of the FTN fibre optic cable.

Ben Lynch, Network Rail’s project manager, provides an overview. “Between the Greatham control area and Ryhope Grange, absolute block working came to an end at 2330hrs on Friday 12th November 2010. The existing mixture of semaphore and colour light signals has given way to track circuit block regulations, axle counter train detection and Dorman two- and three-aspect LEDs. All signals within the scheme are plated with the prefix NS to signify the Northallerton to Sunderland route. Bidirectional signalling has been retained through Hartlepool Station where all through passenger trains use a common platform. There is also bidirectional signalling at Seaham to facilitate access to the Seaham Docks branch. The 12-mile plain line section between Clarence Road and Dawdon has been split by two-aspect signals in order to halve the headway. Hot axle box detectors have also been provided on this stretch.”

Medium voltage DC track circuits have been used but Thales FieldTrac Az LM axle counters have been installed at Stranton, where the line runs close by the sea defences, and between Clarence Road and Dawdon. Use of this axle counter technology required special endorsement by Network Rail’s Infrastructure Safety Review Panel (ISRP).

Singnalling goes undercover two aspect LEDs
New two-aspect LEDs replace Hall Dene's Up Distant and Ryhope Grange's Down Distant signals

Interlocking interface

No significant changes have been made to the track layouts although two trailing crossovers have been removed in the Seaham area. Point actuation is by clamp locks – technology that is not new to the area. In fact the facing crossover points at Clarence Road were the only ones within the scheme that required conversion from mechanical to power operation.

Two MCB level crossings – Church Street (Hartlepool) and Hall Dene – have been entirely upgraded and provided with replacement REBs. These are now remotely operated by CCTV from Ryhope Grange signal box. A footpath crossing overseen by Dawdon box has been replaced by a large footbridge. Between Stranton and Cliff House, a 1½-mile long Up goods line has been out of use for many years and the track is unusable, but the entrance and exit points and signals have been fully incorporated into the new scheme. There are currently no plans to relay the loop but it would now be straightforward to restore it to use if warranted by traffic levels.

Ben continues, “At Ryhope Grange signal box, the new signalling is based on an Invensys Rail Westlock computer-based interlocking interfaced to a Westcad control and display system. Five flat screen displays are used – three for signalling, two auxiliary screens and two for level crossing CCTV.”

In what must be an unusual situation, the signaller’s work at Ryhope Grange is now split between rolling a tracker ball and swinging the levers of the existing 40-lever mechanical frame. The latter is retained to operate the local layout, albeit working power-operated points and colour light signals. Ryhope Grange box fringes to Tyneside IECC and remains the junction for the branch to Sunderland South Docks. The Westlock interlocking installed by the project will have the capacity to include the Ryhope area so no separate interlocking will be required for future expansion.

At Seaham gate box, the footpath wicket gates are fully interlocked with the signalling. Only when they have been electro-magnetically locked and the crossing keeper has pushed the ‘crossing clear’ button can the interlocking then set routes over the crossing. Also, the Ryhope Grange signaller is only able to give the release to Seaham to unlock the gates if a route is no longer set over the crossing and the relevant track circuits are clear.

History dismantled

Two new 650V signalling power supplies have been provided. One is located in a new REB opposite the site of Stranton signal box and feeds north. The second is sited at Easington and covers the area northwards from there. An existing supply at Sunderland has been extended to encompass the Ryhope Grange area.

Stranton signal box, dating from 1911 and containing a 30-lever McKenzie & Holland lever frame, was pulled down by HMC Dismantling & Demolition on Saturday 13th November. Hall Dene box, of 1905 vintage and featuring a similar 21-lever frame, had been demolished the previous weekend to provide space for realignment of the roadway and a wider footpath. Clarence Road, with its 30 levers, was to follow it into oblivion over the night of 20th November and Dawdon (IFS panel) one week later.

Some of the old equipment has been saved by heritage railway groups, notably the semaphore signal that the aforementioned lady sadly missed at Seaham. Recovered by the Stainmore Railway Company, it will find reuse at its Kirkby Stephen site. The Aln Valley Railway has made use of the lever frame from Hall Dene box and the Lincolnshire Wolds Railway has received several colour light signal heads.

Combating crime

With minimal publicity, installation of the new signalling has taken place over an 18-month period, involving more than 160,000 man hours. Impact on train services was minimal too, as most of the work was undertaken during night-time possessions.

“The Durham Coast route is a vital part of the community” asserts Warrick Dent, Network Rail’s area general manager, “providing both local and intercity passenger services as well as a busy freight route – keeping lorries off the roads. Unfortunately this area is a notorious cable theft hotspot so we have taken the opportunity of this project to protect the new system by making the cables more difficult to steal and easier for police to trace if they are taken. These anti-theft measures, along with the new, modern equivalents, will help us to deliver a reliable railway at reduced cost and with potential for increased services in the future.”

All the cabling is hidden from public view as the result of steps taken by the project team. Ben Lynch explains that “Because of very high levels of vandalism and cable theft on the Durham Coast route, all of the new lineside cabling has been buried in deep ducting. Some of these 200mm diameter pipes have been capped with concrete. We have even needed to bury all the tail cables in order to beat the theft problem and the inspection chambers are buried under 200mm of ballast – we have to use GPS to locate them!”

“In all, we have 30km of buried cable route” continues Ben. “This work has been undertaken by Network Rail’s maintenance team and I have been most impressed by the way they have worked with the principal contractor. In order to protect our infrastructure and ensure the safety of our staff during the installation of valuable assets, it was necessary for us to devise a security strategy which had the buy-in of the British Transport Police and our own security force, as well as other major stakeholders. This has paid off as there have been very few incidents of cable theft.” The cabling itself is of an anti-theft type manufactured in Spain (see Issue 64 February 2010).

Signalling goes undercover Ryhope grange box
Westcad and McKenzie & Holland side-by-side in Ryhope Grange box

Future proof

Ben Lynch is keen to praise the role played by his maintenance colleagues. “This project has been a credit to the key personnel involved. Network Rail’s own maintenance team has undertaken not just cable route installation but also plain lining and the fitting of insulated block joints and closure rails. Even though there was no commercial tie-up, our maintenance team and the various contractors have dovetailed very well in order to ensure the success of the project, which has been delivered on time and within budget.”

The completed signalling upgrade has increased the capacity of the line in anticipation of the route being used for additional freight traffic diverted from the East Coast Main Line. Northern Rail presently provides an hourly passenger service from Newcastle to Middlesbrough and beyond. There are also two trains to Darlington which start and terminate in Hartlepool. Grand Central runs four return services daily between Sunderland and King’s Cross. The northern part of the route, between Sunderland and Newcastle, is electrified with 1,500V DC overheads and is shared with Tyne & Wear Metro services. Signalling on this section was transferred to the Tyneside IECC in 2002, eliminating the signal boxes at Sunderland, East Boldon, Boldon Colliery and Monkwearmouth.

It is anticipated that further route developments will take place in the future but nothing is currently confirmed. Such enhancements are unlikely to occur during Control Period 4 but the lever and tracker ball combination at Ryhope Grange would seem to be only an interim solution. Whatever the future holds, the highly robust and adaptable signalling solution now installed should ensure that both passenger and freight operators alike are well placed to provide their customers with an efficient and unhindered service.

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