Located within the station throat at Liverpool Lime Street station, and standing in a deep cutting, is Liverpool Lime Street signal box. It was built to the London, Midland and Scottish Railway Type 13 design and commissioned on 25 January 1948.
The interlocking is a 95-lever Westinghouse Brake and Signal Style ‘L’ frame and is believed to be one of the last such lever frames operated by Network Rail. It controls the layout in the station throat and on the approaches through Lime Street cutting.
The deep four-track cutting extends to Edge Hill, just over a mile away, with seven short lengths of tunnel to support various roads and buildings.
The signal box utilises miniature levers, special electric lever locks, lever bands and associated relay-based circuitry. Given that the equipment is nearly 70 years old, it is in remarkably good condition. However, the expertise to maintain and service the frame is now limited to a small number of staff, a number which is decreasing every year. The condition of the (newer) supporting signalling equipment, such as points, signals and relay locations, is becoming increasingly poor, so a large-scale renewal programme has been instigated.
As is often the case with a major resignalling, an opportunity to improve the railway during the development has been identified, but this would not be without some difficulties and challenges – and additional costs. It may be possible to simply re-signal the layout ‘as is’ (but to modern standards) as the cheapest option; however, there would still be a significant cost and this would not deliver a better railway.
There are many stakeholders involved, including the train operators using the station, other local rail projects, the city of Liverpool and various organisations in the North West. Liverpool Lime Street is also key to the Northern Powerhouse strategy.
Building Information Management (BIM), 4D modelling and video simulation are all being used extensively as part of the planning process. Most of the proposals are still being discussed and developed, and are subject to funding being authorised. Rail Engineer recently met the project team to learn about the development and the proposed designs.
Looking from the station entrance into the station, the platforms are numbered left to right and from 1 to 9. Platforms 1 to 6 are used predominantly for local services and lie in the North Shed of the station, while Platforms 7 to 9 in the South Shed are used for longer distance services and longer trains.
It is currently quite a complex layout, so a look at the ‘before’ and ‘after’ layout graphics could help understanding.
The wide bay that contains Platforms 1 and 2 has an additional stabling siding – ‘A’ – running in between the two platform-facing tracks.
Similarly, the bay for Platforms 3 and 4 includes siding ‘B’.
There were originally two sidings between Platforms 5 and 6 – ‘C’ and ‘D’ – but siding C was removed in 1948. Platform 6 has quite a kink in it, which causes problems with signal sightings.
In the South Shed, what would logically be platform 7 is in fact just siding ‘E’ – the support columns for the station roof are close to the platform edge and preclude it from being used for passengers. So Platform 7 is where you would expect to find Platform 8.
There is a wide space between the last bay for Platforms 8 and 9. Formerly, this space was used for an access road, with a short bay platform at the top end protruding through a small bridge. This has also been removed, as has the bay on the far right that used to be Platforms 10 and 11. The space between platform faces 7 and 8 is now used for waiting rooms and a redundant Post Office building.
Removing the sidings will allow wider platforms to be provided in order to improve passenger flow and footfall. The current proposals under discussion are for platform 1 to be taken out of use, which will allow the remaining platforms to be lengthened to allow for a minimum of six-car trains. Platform 6 would be straightened to improve signal sighting and, after renumbering, will become platform 5.
The buildings between Platforms 7 and 8 (pictured right) will be removed and the old short bay reinstated and lengthened, creating two new full- length platform faces. This is not quite as simple as it may appear, as it will require extensive excavation through sandstone rock together with the infill of the GPO mail shaft tower and the service tunnel that connected it to an empty mail sorting office behind the signal box, which is now owned by Liverpool University. At least some of the excavated stone can be used for the infill, but it will still require many tons of rock to be taken away.
The new layout will provide five platforms on each side of the station, with the long distance platforms in the South Shed extended to 266 metres.
There is an old service tunnel which linked all platforms and was serviced by lifts running under the station at the south end. It has not been used for some time and it will require infilling or strengthening to accommodate the new track layout. The tunnel was considered as a cable route across the station, but this was discounted due to its poor condition, flooding risk and working in confined spaces.
The current layout is complex, slow and is unable to be maintained using mechanised plant. It could not be replaced exactly like for like as it would not comply with current standards. A number of options were considered, and the current proposal is to provide a layout which will allow trains to be predominantly routed to and from platforms 1 to 7 to the slow lines, and platforms 3 to 10 to the fast lines.
The proposed layout will facilitate an increase in departure speed from 15 to 25mph and, with the switches and crossings spaced further away from one another, will improve access for mechanised maintenance. The existing shunt neck (in the centre of the layout) may be abandoned in order to achieve maintenance and track alignment improvements. Under the new layout, the home signals are closer to the platforms and most platform-to-platform moves can be done under a main route rather than a shunt move.
Overhead electrification works
New Mk3D fixed tension overhead line equipment (OLE) to support the new track layout between Liverpool Lime Street and Edge Hill
will be required. This will include a significant number (around 20) of motorised switches to be mounted within the rock-faced Lime Street cutting. Ahead of the main commissioning, new multi-track OLE structures will be mounted on preinstalled gallows brackets using road-rail cranes.
In order to facilitate the new track and points layout stages, there will be a requirement to modify the existing fixed-tension OLE system by installing new wire runs and section switches, modifying existing wire runs and OLE switching, and moving section insulator limits. There may also be a need to install temporary OLE sectioning and switching for shuttle service during the main station blockade, and for the protection of platform construction works, although this is not agreed yet with all stakeholders.
The project is considering the use of motorised earthing switches for the overhead line. This is on trial in other parts of the network and is a faster and safer way of providing local earths in order to carry out maintenance. If provided, this will be the first use of such technology in the North West.
New signalling equipment may include Frauscher wheel sensors, standard strength AWS (permanent, electro and suppressed), TPWS, LED signals and indicators, ‘right away’ and ‘train ready to start’ switches, and route lockout devices. All points operating equipment will be SPX In-bearer Clamp Locks (IBCL) with condition monitoring. The signalling will be connected via the FTNx IP transmission network back to the Manchester ROC (rail operating centre) where a computer-based interlocking will be provided.
Lime Street Control is a signalling control method, used at a number of terminal stations, which uses the configuration of the train detection system to check that a platform has sufficient length before allowing the protecting signal to come off. It was first installed at Liverpool with the resignalling in 1948 and, needless to say, a form of Lime Street Control will again be provided, to enable the automatic route-setting system (ARS) to set into occupied platforms, subject to the train length conditions being proved by the system.
Due to the limited clearances in the Lime Street cutting, consideration is being given to not providing ladders and walkways to the new signal gantries. Therefore, once the gantries are in place, access will only be via work platforms or tower scaffold although, with LED signals and self- reporting equipment, this will be less of a problem.
An interim signalling arrangement is being considered to support a single line shuttle service between Edge Hill and Liverpool Lime Street on the Up Slow/Platform 1 line during the main station blockade. A proposal is being developed to minimise the volume of abortive works and equipment (so the skills required to work on 60-year-old equipment are still required, even for a complete signalling renewal).
The bi-directional single line working will involve alterations in existing location cases in the Liverpool Lime Street Interlocking area, although alterations to the actual lever frame and circuit controller wiring will not be needed. New relay circuitry will be cut into the route selection level of the signal levers, sometimes referred to as the track locks. This may require a temporary non-compliance and the provision of new sealed units around the locks to prevent any unauthorised tampering.
The team is planning to make the bidirectional single line working switchable. During normal operations, the bidirectional controls will be disabled and normal controls restored to the signaller. The bidirectional working can then be switched back in again to support the requirements for the shuttle service during the main blockade.
There is a significant amount of signalling stage works required for point laying – eight ends of points will need to be detected in the existing signalling system as well as new points brought into use. There will also be the requirement to relocate signals A (controlling the exit from Platform 7), B (Platform 8), C (Platform 9) and F (Platform 6) during the stage works while the platforms are being modified. This will also involve track circuit modifications, particularly for the introduction of the new Platform 8.
The re-control of Edge Hill signal box to the Manchester ROC may be undertaken as part of this project and, if so, will require the replacement of the existing Electronic Route Setting Equipment (ERSE) cubicles at Edge Hill Relay Room. If this goes ahead, the plan is to carry out a significant period of rehearsal testing between Edge Hill and the Manchester ROC prior to the final commissioning and transfer of control. The commissioning of Edge Hill re-control would be carried out in the final weeks of the main Liverpool Lime Street blockade.
As well as the FTNx IP connection back to Manchester ROC, the telecoms requirements will include customer information and public address facilities for the new platforms.
Currently, all the lineside equipment is housed in location cupboards deep within the Lime Street cutting. This makes maintenance difficult and a safety hazard. While modern equipment will require less maintenance, it will still need some. In particular, electronic switches and routers will require upgrading and replacing a number of times throughout the life of the overall signalling asset.
The project team was tasked with finding space for equipment located on the surface with safe, easy and maintainable access. Five locations have been identified on redundant bridges and areas of land, some of which will include leaseback or purchase. This will produce a benefit in that the inspection and maintenance of the structures will revert to Network Rail, and therefore the management of the assets and the associated risk that may affect the operational railway will wholly be in the control of the infrastructure manager.
At St Andrews Street, an area of land has been identified in front of the ‘Bullring’ mural. This commemorates the life and times of people who lived in nearby St Andrews Gardens. The gardens were opened in 1935 under a city housing programme and the sweep of encircling balconies prompted the nickname ‘The Bullring’. The mural is an important local landmark and was unveiled by HRH Queen Elizabeth and Prince Phillip in July 1989.
It is proposed to re-engage the original artist to create an improved mural as part of a curved security wall around the signalling equipment. While this is an additional expense to the project, it will contribute to the local environment and community. There has already been local media and community involvement in the possible return of HRH, and the project team may have to contact the royal household to see who is available to unveil the new artwork – not something found on a normal signalling project task sheet!
New power supply points and telecoms transmission equipment will be provided near to the existing Lime Street signal box. However, the signalling equipment at Lime Street could be placed on Platform 6, a central location from which cables can run to all the point ends and signals in the station.
The proposed model for delivery is hub and spoke, led by Network Rail IP Signalling (also responsible for signalling, operational telecoms, E&P and SCADA works), supported by Network Rail IP Central (for all civil engineering and station works) and Network Rail S&C Alliance (for all track and OLE works)
A staged delivery approach will be required to reduce the disruptive access required to deliver this complex project. Civil engineering, track and overhead electrification activities will be delivered prior to the final blockade. This will provide the opportunity for the signalling trackside transmission system to be thoroughly tested prior to entry into service.
The project may have interfaces with other commissionings as part of the Huyton and Weaver to Wavertree re-signalling, together with the possible delivery of the re-control of Edge Hill to the Manchester ROC.
The new crossover ladder at Crown Street will be installed early in the project but will not be commissioned until later. Switches and crossings will be installed at the entrance to the station to enable platform phasing in/out during the lead up to final commissioning.
Ten of the total of 24 new point ends will be installed prior to the main commissioning. One advantage of bringing the points into service in stages is that it allows the significant platform alteration works to be carried out in a phased manner, which will keep the final blockade and station closure requirements to a minimum.
The single bore tunnel at Lime Street provides a natural physical barrier to carry out works during the bi-directional shuttle service. This will be supplemented in the station area by sequencing the works in such a way that the boundary between the operational service and lines under possession is managed effectively, with physical barriers protecting construction staff.
There is a high level of ballast contamination in the Liverpool Lime Street station area, predominantly asbestos and train discharge. The planning process will need take this into account to ensure its safe removal and transportation to a suitable waste facility. It is proposed that platforms 6 to 10 will have new buffer stops installed, with the re- use of existing buffer stops for platforms 1-5 subject to a risk assessment and a condition survey.
Demolition and excavation works within the station will be undertaken with a material holding point near to the Lime Street signal box before removal by road. This will require works to the existing road-rail access point, the relocation of existing GSM-R equipment on Platform 8, and a small section of the platform being taken out of use in order to demolish the redundant mail building and waiting rooms, although the exact staging strategy is still under discussion.
The resignalling of Lime Street is a complicated, significant project with many interfaces and risks, but it also provides the opportunity for a much better layout to suit today’s railway and one that is maintainable, sustainable, and is able to support the Northern Powerhouse. Rail Engineer looks forward to reporting on the implementation and completion of the project once it is authorised.
Written by Paul Darlington. Thanks to Ian Fury, Chris James, Mick Turner, Colin Saunders and Claire Beranek of Network Rail for their help with this article.