Over the weekend before Easter 2018, Siemens Rail Automation commissioned its low-cost digital-ready modular signalling solution on the North Wales Coast (NWC) resignalling programme as part of Network Rail’s £50 million North Wales Railway Upgrade Project.
Control of the line is now carried out from the Wales Rail Operating Centre (WROC) in Cardiff. The project delivered a genuine low-cost resignalling for around 75 per cent of a conventional one, so finally a lower cost signalling solution for such routes is now available.
Traditionally, 50 per cent of the cost base of any signalling project has been associated with the supporting steelwork and copper cabling located trackside, together with the construction of concrete foundations on which to install it all.
In addition, with conventional signalling, there are often a number of bespoke or non-repeatable signalled scenarios, which have to be individually designed and tested. This low cost signalling solution is designed to remove these costly items.
The Siemens Trackguard Westrace and Controlguide Westcad systems provide a more efficient and future-proof signalling system with much-reduced material content, rapid and low-cost installation, and lower ongoing maintenance and operational costs. They also provide the foundation for the future fitment of ETCS and traffic management system products, such as dynamic route setting and digital conflict resolution. It therefore meets the Network Rail requirement of being ‘digital railway compatible’.
Although the technology was proven in the Crewe-Shrewsbury modular signalling pilot scheme, Siemens has taken that concept and further developed it, leading to the launch of the low-cost, digital-ready system that has been demonstrated for the first time as a ‘production process’ on the NWC project. One minor change is that the grill platform base for the object controllers has been replaced with a solid concrete one, to reduce the amount of screw pile foundations required, but no other changes to the system have been made.
At the heart of the low-cost signalling solution is Siemens’ Trackguard Westrace Mk2 computer-based interlocking, enabling signalling schemes to be delivered from just a small range of core products. These include object controllers, plug coupled cables, axle counters and lightweight signals.
This enables a number of standard signalling data templates to be used, reducing the engineering resource required for any given scheme significantly, and making the validation and verification processes much faster and more straightforward.
The modular-signalling concept is specified by the Network Rail Modular Handbook. To simplify the system, this includes a number of constraints such as no more than five stopping trains an hour, or three routes from a main signal, and no banner signals or enhancements.
However, Siemens believes that its Westrace product is powerful enough that it can easily exceed the Modular Handbook requirements. For example, a functionality module for four-aspect signalling is available, although it was not required for NWC.
Forming part of Network Rail’s Railway Upgrade Plan, the project covers a 30-mile section of the line between Shotton and Colwyn Bay. At an early stage, the NWC programme was identified as an ideal project for modular signalling, as it was developed specifically to allow lines of this type to be cost-effectively upgraded.
The signalling solution is essentially a modern version of absolute block, with ‘islands’ of signalling separated by plain line. Train detection control is by track-circuit block using axle counters and existing train movements, and capacities are replicated in modern form to avoid Network Change issues as far as possible. For the NWC scheme, three ‘islands’ of signalling have been provided at Flint, Mostyn and Rhyl.
Each island is provided with a modular equipment housing (MEH), to house both the Westrace interlocking and its interfaces to object controllers that control signals and points. Over the three islands, a total of 85,000 metres of double-insulated super-armoured fibre-optic cable (DiSAC), 40,000 metres of power cable and 45,000 metres of tail cables have been provided. Approximately 30 per cent of the cabling has been installed in troughing, with 70 per cent anchored.
Siemens looked long and hard at the lessons learned from the Crewe-Shrewsbury pilot. One learning point was to avoid any rework and to carefully develop and lock down the requirements early in the design. This enabled a sequential design approach, rather than the riskier parallel design process.
The team included experienced railway signalling engineers together with engineers from other safety critical industries who were not constrained with the traditional ways that railway signalling has always been delivered. This enabled fresh ideas and innovative solutions to be introduced, along with best practise from other industries.
It is important that remits for these types of projects are performance-based with intelligent requirements, and care needs to be taken to avoid prescriptively specifying what has previously been remitted via ‘copy and paste’ from older schemes. Otherwise, further innovation and the opportunity to reduce costs may be constrained.
Crewe-Shrewsbury was tested both in the factory and on site but, for the NWC scheme, greater use of the factory off-site hangar testing facility has been made, with reduced on-site testing to further contain costs. This, along with using templated designs, standardised plug-and-play equipment and the fast and efficient installation process, has proved the benefits of the modular concept.
Testing the system in the hangar facility at the factory has a number of advantages. A major cost of any conventional scheme is getting people to and from site. It’s also far safer working in a controlled environment, rather than travelling by road (itself a risky undertaking) to a live railway worksite. Fewer disruptive possessions are needed, as well as it being far easier to effect changes to the system, which may be identified by the testing, while it’s still in the factory.
The new workstation at the WROC replaces the signal boxes at Rockcliffe Hall, Holywell Junction, Mostyn, Talacre, Prestatyn, Rhyl No 1 and Abergele. Rhyl No 1 is one of a pair of Grade II listed London & North Western Railway boxes at Rhyl, with Rhyl No 2, at the western end of the station, closing in 1990.
Holywell Junction, Abergele and Mostyn are also Grade II listed. However, plans are additionally in place to use some of the other non-listed structures for new purposes.
The local council, MP and community are all involved with Network Rail in plans to retain Prestatyn signal box. Some of the ideas being proposed include a visitor attraction, such as a railway heritage centre, which would link with the old Prestatyn/Dyserth railway line and Offa’s Dyke footpath. This will help the council to promote and develop its theme of Prestatyn being a ‘walkers welcome’ town.
Talacre signal box is being sold to the neighbouring industrial estate for use as an office. And the bottom portion of Rockliffe Hall signal box is being retained as a rail training centre for Rhyl College.
The manual gate box at Tyn y Morfa level crossing has also closed. Rather than being operating with obstacle-detection radar, the level crossing has been upgraded to a manually controlled barrier with CCTV operated from the WROC.
As this is likely to be the only manually controlled barrier level crossing with CCTV on the route, it can easily be operated within the overall signaller workload. The Siemens S60 barrier machines are driven directly from the Westrace equipment, without the need for interface relays, to improve reliability.
A major programme milestone was achieved in September 2017 when the first of the three signalling islands was delivered to site, following the successful completion of hangar testing at Chippenham. Installation of all the signalling islands and equipment was completed by the end of January 2018. With the system installed and tested, it allowed two months of powered-up ‘soak testing in shadow mode’ to prove the systems reliability before commissioning.
Power for the signalling object controllers is via 24VDC battery-backed four-hour power supplies, and the size of the batteries is one limiting factor on how busy a route can be. An object controller is used to control each signal and point machine as well as the fringe signalling interfaces.
The LED signals are provided by VMS and train detection is via Frauscher axle counters, to deliver maximum availability with the optimum level of safety and low life-cycle costs. In the NWC scheme, 54 new digital LED signals have replaced 96 existing mechanical/colour light signals, enabling bi-directional running on both the existing roads. Train detection is provided by 92 new axle-counter heads, and 21 points have been re-controlled/converted to in-bearer Clamplocks.
A loop has been removed at Abergele & Pensarn station by extending the platform width using an innovative lightweight polystyrene-block solution – designed, supplied and installed by MegaTech Projects as a subcontractor to Alun Griffiths – to successfully overcome challenging soft ground conditions on the site.
A new LED lighting system, signage, waiting shelter and bike rack have also been installed at the station, along with work to improve the drainage and 540 metres of plain line.
Switch and crossings (S&C) and associated track renewals have also been installed on the route. This includes 2.4km of plain line, a passing loop, 13 point ends and 24,000 tonnes of new ballast at Mostyn; two-point ends, 160 metres of plain line and 1,500 tonnes of ballast at Rhyl; together with four-point ends and 220 metres of plain line at Flint. The Colas Rail S&C South Alliance has delivered all the track work.
A large part of the success of this project was down to the collaborative approach taken by the teams, with a joint project office established at Prestatyn for all involved. The ‘working better together’ objective delivered benefits, such as minimal changes to scope and the scheme delivered within budget.
As well as Siemens and Colas Rail, Network Rail internal Works Delivery installed supporting infrastructure such as walkways and hollow bearers along with the recovery of some of the old sidings. Alun Griffiths, as previously mentioned, delivered the platform works at Abergele & Pensarn and Linbrooke carried out the telecommunications changes to FTNx.
The signalling system has been developed to operate via Network Rail’s internet-protocol (IP) Fixed Telecommunications Network known as FTNx. This provides both resilience to failure with reduced operational costs and provides Network Rail with complete management responsibility for the telecoms services, rather than using ‘bought in’ telecoms links.
New FTNx access equipment and routers have been provided to connect to the existing telecoms nodes at Chester and Shrewsbury. Two independent Cisco ASR903 routers are installed at each telecom access node, serving an MEH island and fringe and providing 10GB links to the WROC. The configuration provides sufficient redundancy to assure that the required availability of the network is achieved.
Due to the redundancies in the transmission system design, failure of a single router or connection at any point in the network will have no immediate effect on the telecoms services.
A second incident would be necessary before part, but not all, of the transmission network would fail. Total loss of communication from a single FTNx node would not in itself lead to failure of the signalling or level crossing control equipment.
To provide diversity, a fibre cable runs west to Llandudno junction via the Conwy Valley, Ffestiniog Railway and mid-Wales route to Shrewsbury, while a second fibre cable runs east to Chester. At Chester and Shrewsbury, existing FTNx router infrastructure is used to reach the WROC. From Shrewsbury, circuits are routed via Craven Arms to Pantyfynnon, Bridgend and thence to the WROC; or via Craven Arms, Newport, to the WROC; or via Chester to Warrington, Birmingham, Stoke Gifford and Newport and then on to the WROC.
The layer 2 and 3 switches within the signalling system are monitored from the WROC via a network management system. Terminals installed at Llandudno junction and Shrewsbury depot are able to connect remotely to the technician’s facility in the WROC to monitor the status of the system. All the routers are monitored and managed from the centralised Network Management Centre (NMC), which manages all of the FTNx network.
The signalling data circuits’ paths through the transmission network are delivered using MPLS (Multiprotocol Label Switching) traffic-engineered pseudo wires. In each case the pseudo wires are ‘route-pinned’ through the network along a chosen path.
Video data for Tyn y Morfa CCTV level crossing is transmitted to the WROC via the FTN SDH (Synchronous Digital Hierarchy) transmission system along with voice circuits for several user-worked and footpath level crossing and signal post telephones. The voice circuits are terminated on the existing Siemens HiPath concentrator system at the WROC in Cardiff.
A train driver travelling from Euston to Holyhead will now only see a semaphore signal at Beeston Castle and Tarporley signal box, between Crewe and Chester, before facing semaphore signals on the approach to Holyhead. So, could this be where low-cost, digital signalling is used next?
The future for signalling renewals has to be more automated standard design, simpler installation and off-site testing – all reducing dramatically the need for access and driving down costs.
Siemens is confident of using these principles to deliver the next phases of low-cost digital signalling evolution, which should deliver a further 10 to 20 per cent savings. The ultimate goal is halving the cost of signalling, while at the same time making the signalling asset base compatible with ETCS and traffic management.
So, the challenge is out. Which route will be the next one to install a low-cost ‘digital compatible’ signalling solution?
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