Written by Clive Kessell for the rail engineer
Much has been written about new signalling schemes on Network Rail, London Underground and elsewhere. The wonders of modern electronics and computer control make fascinating reading even if the cost creates considerable adverse comment on occasions.
Main line and metro railways are not alone in having challenges for controlling an ever-increasing growth in traffic. The UK’s heritage railways are the most prolific in the world and there seems no stopping the emergence of new schemes for the reinstatement of abandoned lines. However, these railways have to conform to the signalling rules for what are generally classified as Light Railways, which, while restricting speed to a maximum of 25mph, nonetheless demand safe systems of operation and control.
The Swanage Railway is typical of the challenges that such lines face. Starting with not much more than a long strip of brown field land, the rebuilding of the railway so that trains could run again took many years. Sorting out the signalling requirements was perhaps an even more significant project and the IRSE Minor Railways section visited the railway on the 15 October to see what had been achieved.
The Wareham to Swanage Railway
Opened in 1885, the line connected the country town of Wareham with the Dorset coast resort of Swanage with a passing loop and station at Corfe Castle. Flourishing for many years, particularly with holiday seaside traffic, it gradually succumbed to growing car ownership and eventually closed in January 1972. The local population had fiercely resisted the closure and efforts to get the line re-opened began almost at once. However the demolition contractors moved in quickly and the line was dismantled from Swanage as far as the Furzebrook sidings serving Wytch Farm Oil field, some 2 miles from Worgret Junction near Wareham. This stub end has proved to be fortuitous in that a mainline connection was retained.
The station buildings at Swanage and Corfe Castle were left although increasingly subject to dilapidation. The preservation society had a daunting task but an ally was found in Dorset County Council who realised that a re-instated railway might offer a solution to the growing traffic problems in Corfe Castle and Swanage. The County Council bought the track bed and thus the route was now secure.
Swanage station was refurbished and by 1979, track was relaid to Herston on the outskirts of the town. Sidings and the old engine shed enabled small steam locomotives and ex BR coaches to commence a short shuttle service. In 1988, the line was extended to an entirely new station at Harmans Cross where a loop was provided for run round purposes.
The big leap forward came in 1995 when the line extended to Corfe Castle and beyond to the park & ride at Norden. The railway became part of the transport system for the district carrying local travellers and holiday makers as well as enthusiasts wanting a steam train ride. Additional locomotives and rolling stock were obtained but the lack of signalling limited the number of trains that could be operated.
Signalling the Line
Initially the run round loops and siding connections were operated by ground frames and hand points. A train staff was initially used for the single line control, but this is limiting when more than one train is in operation. The passing loop at Harmans Cross was time consuming to operate and it was decided that proper signalboxes would be needed at Harmans Cross, Swanage and Corfe Castle. A heritage railway must be mindful of the image it is trying to portray and thus electronic interlockings and colour light signals are not generally used even if they could be afforded.
The gradual modernisation taking place on Network Rail throws up redundant equipment and our heritage railways make good use of this. Mostly it comes free of charge but with the railway paying for delivery to site. A whole variety of signalling equipment can be obtained this way ranging from lever frames, circuit controllers, electric locks, relays, point rodding, signal posts / arms and level crossing equipment. Some railways have obtained complete signalbox structures. Getting the bits is not normally the problem; designing the circuits / mechanical layouts, installing and testing the equipment and getting it commissioned to the required safety standards is where the time, professional skill base and finance are required.
To operate a reliable two train service required this location to become a fully signalled passing loop. The signalbox has been sited on the Up side just north of the station and was a new construction in traditional L&SWR style. Sound foundations ensure that the structure can withstand the mechanical stresses associated with lever pulling. The frame came from Gunnersbury and is of Stevens manufacture with 22 levers having lever locking, i.e. the locking tappets are directly operated by the levers’ movement. Underneath is the usual mixture of cranks and pulleys secured to a bedding plate. A partitioned area forms the relay room and power supply. Old style shelf relays control all the vital circuitry.
The box has two Tyers electric key token instruments for the single line sections to Swanage and Corfe Castle. When the box is open, tokens are exchanged with the drivers in the normal way. However, if only one train is in operation, the box can switch out for long section working between Corfe Castle and Swanage using Tyers No 6 Tablet Instruments. A ‘King Lever’, released by Corfe Castle and Swanage, enables Harmans Cross to switch out by clearing Up and Down signals for the Down platform. The king lever, when finally reversed, frees the tablet to be extracted and handed to the driver for the train to proceed. The king lever then prevents any untoward operation of levers until the box re-opens whence the process is reversed.
Other levers connect the rodding to the loop points and their facing point locks at each end of the station. There are two sidings used to store rolling stock not needed for the day’s service. Signals are upper quadrant distant, home and starters plus disc signals to control shunting movements. The distant signals are pulled only when the box is switched out. The signal arms are mounted on lattice posts, which were fabricated by Swanage Railway volunteers. The box was started in 1995 and completed in 1997.
A signalbox had existed here but was demolished when the section from Corfe Castle became ‘One Train Working’ towards the end of BR operation. When the line reopened, ground frames controlled the reinstated run round loop and sidings. This was adequate at the time but very limiting, with no direct access to the bay platform for passenger trains. Thus the decision was taken to build a new signalbox, this time sited on the Down side as insufficient space existed at the original box location because the land was leased out by the Council.
Box construction followed a similar pattern to the one at Harmans Cross, with the same high standard for mechanical and electrical installation being achieved, but with a Westinghouse A2 frame of 40 levers from Brockenhurst B. This type of frame has catch handle locking where the tappets are moved by both the pulling and release of the catch handle when the lever is reversed. Tyers key token instruments control the working to Harmans Cross but when that box is switched out, a Tyers tablet instrument controls the working to Corfe Castle. Two king levers allow the box to be switched out with both Up and Down signals pulled off for the main platform, a tablet being in use for long section working to Corfe Castle. This arrangement is the minimum facility for operating a single DMU train service in the evenings.
A signalbox was provided at Corfe Castle for the line opening in 1885. This was located on the Down platform and had 11 levers. Of timber construction, it lasted until the 1950s when it became unstable and was replaced by a 12 lever frame located in the old Porters’ Room within the main station building on the Up platform. This continued in use until the line closure when the room was locked up. Fortunately the demolition contractors failed to find the frame and it remained in situ. When the re-laid line reached Corfe Castle in 1995, all trains to and from Norden used the Up platform and thus signalling was not needed. By 2005, the increasing train service demanded that the passing loop should become operational and the frame was restored, re-locked and brought back into use with either tablet working to Swanage or key token working to Harmans Cross. One train working with a train staff was used for the short section to Norden where the loop exists only for engine run round purposes.
A vision to restore a signalled mainline connection at Worgret plus the increasing number of charter trains arriving from the national network meant that the Porters’ Room signalbox was inadequate. The decision was made to build a new signalbox on the site of the original one and equip it so that it could remotely control the loop at Norden and its adjacent level crossing as well as providing the interface to the mainline signalbox – currently at Wareham but eventually to be at Basingstoke.
Contractors were engaged to build the box foundations but the main structure has been done entirely by volunteer labour. The frame is a 32 lever Westinghouse A3 style being made up of recovered equipment from both Brockenhurst A and Broadstone. Both had been stored in wet conditions for some time and the steel levers were very rusty, an emery machine being needed to bring them back to mint condition. The underside locking area has a mass of cranks, rodding, pulleys and wires that exit under the platform face – not the easiest of places to work. A relay room accommodates all the relays, wiring and power supply, all installed to a very high standard. On the operating floor are three single line machines: a tablet machine for long section working to Swanage, a token machine for working to Harmans Cross and a new ‘No Signalman’ machine for the short section to Norden.
Summary and Future Plans
Signalling the Swanage Railway has been a major achievement. Most of the work has been done by volunteers with no previous signal design or installation experience. The enthusiasm and dedication are an inspiration for all. There is more to do however. The track was extended from Norden to meet the remaining branch line at Motala where opposing points protect movement between the Heritage Line and Network Rail, thus allowing charter trains to run through under special arrangements.
Dorset County Council is keen to establish a regular ‘Amenity Service’ from Swanage to Wareham. This will entail running a DMU train beyond the present Norden station up to the main line at Worgret Junction and into Wareham station. Network Rail, in the process of designing the resignalling of the Dorset Coast line, were prepared to include a signalled connection to the Swanage branch for a cost of £3 million. Such is the difference in costing between the commercial railway and the heritage sector! Fortunately, the county council has agreed to underwrite the cost. This will provide the junction control signals and also signals down the branch to enable a train to be clear of the main line even if the section to Norden is occupied. The exact arrangements for the necessary token working are still being worked out.
The loop at Norden must remain as the park and ride service is key to the heritage railway income. The points and signals may be motorised and the adjacent level crossing equipped with full barriers and CCTV surveillance, all to be controlled remotely from Corfe Castle box. Wareham station does not currently have a bay platform so occupation of the main line by Swanage trains will need to be a slick operation. A bay might be provided if the service is a success. All of this has still to happen but 2013 is the aim.
Thanks are expressed to Mike Walshaw and Mike Whitwam who not only have done much of the work but also gave their time freely to show us around this amazing resurgence.