THE SIGNAL BOX

BRANCH LINES

 

THE WEST SOMERSET RAILWAY

A Description of the Signalling
by Kevin Weston

Blue Anchor

Blue Anchor boxBlue Anchor is the other signal box on the branch that retains most of its original equipment. It is of brick construction and the opening date is generally given as 1904. The layout is simple, a crossing loop with a siding at the Minehead end. Three camping coaches are parked on the siding, although the point was disconnected when the line reopened. Some of the equipment in use dates from the opening of the signal box. There is a road crossing at the Minehead end, protected by wooden gates operated by a wheel in the signal box. This is the last set of original GWR gates in use; all the others on Railtrack have been converted to barriers. It is known that the crossing was rebuilt in 1955, we have the drawings for this work and they indicate that the operating mechanism was overhauled but not altered. The road approaching the crossing from the sea front is on a sharp bend and, despite the 30 miles per hour speed limit; some car drivers still come around the bend too fast and find the gates across the road. The gates are hit at least once a year and the drivers have some original excuses. One of the best was on a summer evening; a train from Minehead was in the process of a run-round move when a car hit the gates, the driver complained that the accident would not have happened if we did not run trains in the evenings. The point at this end of the loop is operated by the original rodding, although it is possible that the point was moved about 20 yards in 1934. This was the date that the loop was lengthened at the Williton end. The Minehead end point retains its original fouling bar for the FPL; the one at the Williton end of the loop was converted to motor operation in September 1995, using a reconditioned Westinghouse Style M3A machine with track circuit locking. Some of the volunteers had complained about the use of this modern equipment, but they have been reminded that this “modern equipment”, based on a 1930’s design, is older that some of the steam engines they drive.

All the signals are BRWR design, erected around the same time as those at Williton. When the branch closed in 1971, all the internal equipment, apart from the lever frame, was removed. This equipment had to be replaced before the signal box could be reopened. The frame has 17 levers with Stud locking and is dated 1903, indicating that it was constructed in Reading Signal Works before the signal box was built. It is believed that this frame is the oldest of its type still in use in the signal box for which it was designed. Railtrack has only one original Stud frame still in use, while several of the other private railways have used reconditioned Stud frames. Token working to Minehead was introduced in 1990 when the signal box there was opened. The WSR has no signalling cable between the two signal boxes; the token operates over a dedicated British Telecom line using a system of ac frequency signals. Six frequencies are required to operate the system, which must ensure that only one token can be removed at any time. While the signal box and station may give the appearance of a country station in the 1950’s, it is an interesting mix of equipment, the modern electronic system for the token is working along side mechanical interlocking designed nearly a hundred years ago.

Token in machine at Blue Anchor

Not all the siding connections are controlled by a signal box but the Railway Inspectorate still require that all facing points on a passenger line are fitted with a Facing Point Lock. Within the control of a signal box, the FPL is either locked electrically through the lever lock or by a mechanical fouling bar. In a block section, some other means is required to interlock the point with the train staff. The normal method of operation is to provide a small ground level lever frame to operate the points. The levers are locked in the normal position and can only be released by a key attached to the train staff. The key is retained in the lock while the points are operated and can only be removed when the point levers are returned to normal. At the present time there are two intermediate ground frames, one at Dunster and one at Washford.

Level Crossings

Williton and Blue Anchor were the only signal boxes in use when the WSR began passenger services in 1976. There are also four road level crossings, which are not located at signal boxes and are not, therefore, under the control of a signalman. Until closure of the branch, crossing keepers had been employed to operate the gates and protecting signals at three of these, while the fourth crossing at Dunster West was under the control of a signal box. The railway at that time was operated entirely by volunteers, and there was no one available to work these crossings. The solution was to convert them to automatic operation. There was no requirement of both tracks to Minehead for passenger trains and it was decided not to reopen Dunster signal box, fortunately, the Railway Inspectorate gave permission for Dunster West Crossing to become “Open”, i.e. no signalling required. The others, at Sea Lane (Dunster East), Leigh Woods and Roebuck required road lights and rail signals. Approaching trains are detected by track circuits, which are long enough to give the road users sufficient warning of the fastest train. The line speed on the WSR is 25mph but the design of the crossings has allowed for 40mph trains slowing down to 25 mph over the crossings. A standard road light unit for level crossings has a steady yellow for five seconds followed by two alternate flashing reds. Two of these units are provided on each side of the crossing. On the rail side, the driver will see a flashing white light when the flashing red road lights are operating but must look out for road users “jumping” the lights. If there is no flashing white, the train must stop before passing over the crossing and the fireman will hand-signal the train when the crossing is clear. New crossings now require a flashing red light to be exhibited to the driver when the flashing white is not shown.

At Watchet, the railway has a very busy footpath crossing between the town and the sea front. Miniature red and green warning lights are provided for indicating to pedestrians. A track circuit and a treadle in each direction detect the approach of trains. This is the only location where ac track circuits are used, standby power in provided by a 24-volt battery through a dc/ac inverter.