Travelling down the Great Western Railway to the West Country is an interesting experience. Immediately out from Paddington, the railway is the most modern in Britain, with new electrification, ERTMS being introduced from Airport junction to Heathrow, new signalling from the Didcot ROC and a superb grade separation at Reading.
Then 1980s technology takes us through Westbury and Exeter power box areas and on into Plymouth with its 1960/70s colour light signals.
Cross the Tamar into Cornwall over the magnificently restored Brunel’s Royal Albert Bridge and suddenly things become very different. With traditional signal boxes, lower quadrant semaphore signals, long block sections and some quaint branch lines, one could almost be forgiven for thinking this was a heritage railway. Yet Cornwall is seen as a growth area, especially for its long summer season holiday traffic as a result of Brexit and the weak pound.
Something has to be done to improve the capacity of the main rail route down to Penzance. In British Rail days, rationalisation went a step too far with part of the main line being singled from just past St Austell to almost Truro. This caused operating chaos, with late running of long distance trains having a potential knock on effect throughout the entire UK rail network. Sense prevailed and the section has since been re-doubled, but the overall line capacity is still inadequate for emerging needs.
Existing signalling and operation
The Plymouth signal box area provides colour light signalling as far as St Germans, then there is a long section to Liskeard, which is the Plymouth fringe box. Liskeard retains its mechanical signal box, with levers working the station area and the junction to Looe.
The next section is to Largin, which is controlled from Lostwithiel signal box covering the short single-line section over two viaducts. The section continues to Bodmin and thence on to Lostwithiel, which has a lever frame for the station area signals and points, including the junction for the Fowey freight line, plus a small NX panel linked, remotely to a solid state interlocking at Par, for control of the sections between Liskeard and Lostwithiel.
The signalling between St Germans and Lostwithiel is by track circuit block (but using axle counters). From Lostwithiel to Penzance it is absolute block with traditional block instruments and bells.
At Par, where the Newquay branch line diverges, mechanical signalling is retained for the station area but with a panel to control the onward section to Truro where intermediate signal sections are provided at St Austell, Burngullow and Probus when this section was re-doubled in 2005.
Truro is the next signal box, again with a mechanical lever frame and semaphore signals but also controlling the branch line to Falmouth including a recently installed passing loop at Penryn to permit a half hour service. The loop is controlled by levers in Truro box via a TDM system to a remote relay room at Penryn, with cabling being provided for the power operated points and colour light signals.
Onwards to Roskear signal box (the London side of Camborne), which has colour light signals controlled from switches on the block shelf, and thence to St Erth, with its traditional signal box and semaphore signals to control the junction for St Ives, ever immortalised by the Flanders and Swann song on branch line Britain. The final block section is to Penzance, where power signalling controls entry to the train maintenance depot and also a short section of single line that provides a single lead into the station throat, the result of a previous rationalisation. This irritation will remain for the time being, but can cause operating delays if trains are running late.
Whilst semaphore signals remain in station areas, distant signals are all colour light and the few intermediate block sections that exist are two-aspect distant and home signals. Lineside cables provide the inter-box communication and the Network Rail FTN (Fixed Telecom Network) fibre-optic cable and associated digital transmission is provided right through to Penzance.
Train services are a mixture. DMUs provide a local service to and from Plymouth and on all the branches. Long distance trains operate to London by GWR Class 43 HSTs, roughly every two hours, and through services run to the Midlands, the North and Scotland as part of the CrossCountry franchise. There is also the nightly sleeper train to and from London, and even a through London to Newquay service during the summer season. Freight services are confined to the cement traffic to Moorswater (near Liskeard) from Aberthaw in South Wales, and clay traffic between Fowey port and workings around St Austell.
Altogether, there are a mixture of services but, with long block sections, a regular clock-face timetable is not possible and the desire to provide a half hour service means that a capacity enhancement is essential.
The upgrade project
Whilst the plan to re-signal the whole of Cornwall and control it from Exeter PSB has been officially ‘paused’, a smaller enhancement project has commenced to improve the line capacity that will meet the franchise agreement with Great Western Trains for the December 2018 timetable change. The ensuing positive result has attracted funding not only from Network Rail but also Cornwall Council and the EU Regional Development Fund.
The project is split into two halves. Amey was awarded the Eastern section and Atkins the West, with a number of new intermediate signal sections being provided plus some renewals of existing signalling equipment.
The Amey contract covers from the Plymouth power box fringe at St Germans to Lostwithiel. A new signal section will be introduced at Menheniot between St Germans and Liskeard comprising a home and distant signal on both lines, controlled from Plymouth box. This involves making alterations to the existing western style ‘turn – push’ NX panel with new ‘dominoes’ and additional signal control switches and buttons being provided by Henry Williams. Another intermediate signal section will be introduced at Bodmin Parkway, roughly half way between Largin and Lostwithiel, with up and down signals either side of the station. These will be controlled from a new push – push NX panel in Lostwithiel box as the present panel has insufficient capacity. At Bodmin Parkway station, two ‘Off’ indicators will be provided for train despatch and on the down line, a white and green banner signal will be included to improve signal sighting.
Control of the new signals at Menheniot will be from a Siemens ‘Westplex’ vital transmission system, with train detection provided by new Thales AzLM K-type axle counters, which also sees replacement of some axle counters of an earlier design. This will ensure a consistent product for the maintenance teams. Around 50km of new cable is being laid and use will also be made of the FTN fibre network to give digital access to some lineside locations.
The Atkins contract covers from Par to St Erth. Since the Par to Truro section already has sufficient intermediate signal sections, no additional capacity is needed. However, from Truro to St Erth, three new signal sections will be provided at Chacewater, Redruth and Gwinear Road, the latter originally being the junction for the long-closed Helston branch. Home and distant signals on both up and down lines will be provided at all three locations, all of which will be controlled from a new ‘One Switch Control’ panel in Roskear box, which will have its ‘western’ style E10K relay interlocking upgraded. The existing signals at Roskear will transfer to the new panel. No changes to the St Erth – Penzance section are needed.
The new signal sections at Chacewater and Redruth will see the section from Truro to St Erth converted from absolute block to track circuit block but with axle counters. Again, a Siemens ‘Westplex’ vital transmission system will control the new signal sections and axle counters using the FTN digital access plus local cabling.
Permanent way and level crossings
No track alterations are needed for this capacity enhancements scheme, so the existing control of the branch line junctions will remain the same.
Level crossing upgrades are required with six User Worked Crossings being upgraded to Miniature Stop Light, to give additional protection to users. These will employ the VaMoS Schweizer equipment triggered from dedicated Frauscher axle counter sections. The AHB crossing at Dolcoath (approximately one mile north of Camborne) will be changed to a four-barrier MCB Obstacle Detection crossing, allowing continued automatic operation but protected by the new section signals. The existing four-barrier crossing at Camborne, controlled by CCTV from Roskear, remains unchanged.
The Equipment Providers
Both Amey and Atkins have engaged specialist subcontractors for the supply of signalling hardware and some software provision. These are:
- Signals – the Collis lightweight structure with a hinged post and including the Collis LED aspects with separate units within the head for red/green or yellow/green;
- Axle Counters – Thales AzLM-K type;
- Transmission – Siemens for the Westplex vital TDM system data and hardware;
- Equipment Buildings and Fitment – MGB Signalling (based in Plymouth) who provide all the combined REB/PSP (power supply) units with integrated UPS and batteries (from AEG) and the external signalling location cases;
- Power – MGB Signalling for the power Distribution Network Operator (DNO) cubicles;
- SSI Data – OSL Rail for the Liskeard to Lostwithiel part of the Amey works;
- New Panel at Lostwithiel – Henry Williams.
Signalling design work has been carried out by Amey from its Bristol office and by Atkins in Swindon, Birmingham and Bangalore (India). Amey has established a depot at Menheniot, with Atkins having a depot at Redruth. Testing is part of their respective contracts.
Network Rail Telecoms (NRT) has done the FTN design and Network Rail staff will carry out the final signalling acceptance. Progress meetings between all three main parties take place on a regular basis, with a formal periodic review every four weeks.
Access to the sites is not always easy but, at Bodmin Parkway, the assistance of the Bodmin and Wenford Heritage line was given to transport the REB and its fitments to the site in the vee of the main and heritage lines.
Commissioning and timetable change
The new timetable is planned for December 2018, so the upgrade work has to be completed by then. The Eastern section will be a three-stage commissioning, with the Plymouth panel alterations scheduled for February 2018 followed by re-control of the Bodmin area in March and the remainder in April 2018.
The Western section will be achieved as a single changeover planned over a three-day period 13-15 October 2018. Thus, some of the benefits will be available for next summer even before the timetable change. The full project should enable a headway of less than 10 minutes to be achieved throughout the Cornish main line.
The scheme is seen as an important ‘stepping stone’, enabling half-hourly services ahead of a larger resignalling scheme that will follow at some future date. The chances are semaphore signals will still be in use for a few more years yet.
Thanks to Paul Munday and Spencer Hobbs from Network Rail, Andy Cobb and Dave Helliwell from Amey and Jon Leach and Stephen Mills from Atkins for explaining the complexities of this project.
This articles was written by Clive Kessell.
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