THE SIGNAL BOX

BRANCH LINES

SOMERSET AND DORSET JOINT RAILWAY SIGNALS

by Chris Osment

Introduction Signal Posts Signal Arms Subsidiary Arms Ground Signals

Introduction

Information on the earliest forms of S&DJR signals is virtually non-existent, but it has been suggested that the Somerset Central Railway used disc-and-crossbar signals similar to those of the Bristol & Exeter Railway, whilst the Dorset Central Railway used disc signals similar to those of the L&SWR. The 1864 S&DJR Rule Book contains illustrations of the former type only and certainly an example existed on the old DCR at Spetisbury until 1901, although it may have been moved there from elsewhere. The familiar semaphore signal probably first arrived on the S&DJR to any great extent with the opening of the Bath Extension in 1874 and the rest of these notes deal with the subsequent period. Some suitable illustrations can be found in "A Pictorial Record of Southern Signals" by GA Pryer (henceforthreferenced as 'PRSS').

Signal Posts

Three main materials were used: wood, steel lattice and old rails. The Bath Extension probably was equipped throughout with wooden posts, which were surmounted by a ball-and-spike type finial. By about 1900 the lattice post had come into use and this was identical to the L&SWR pattern, as was the finial (PRSS Fig 15). Signal posts constructed from old rails were a common sight on the Southern Railway, but it is not often realised that this method of construction was neither invented by, nor exclusive to, the SR as the S&DJR had erected a considerable number of rail-built posts prior to the Grouping.

The S&DJR appear to have been using rail-built posts by about 1905-10, although it may have been superseded prior to the Grouping, as at least one S&DJR rail-built post is known to have been replaced by a lattice post. Exactly when the SR started using rail-built posts seems unclear, but their first widespread use appears to have been on the Wimbledon-Sutton line in 1929 (when they were described as "a novel idea"), so the SR pattern may have begun to appear on the S&DJR in the early 1930s.

The method of construction varied between the two Companies. The S&DJR pattern normally consisted of two rails bolted tightly together, so that at a distance they appeared to be a single rail and sometimes are erroneously described as such in photograph captions, even though the heads of the bolts holding together the two rails can be seen. Although the two-rail method provides better strength, it appears that some examples did have only a single rail. The SR type had two rails, held about 9" apart by spacers in an elongated 'H' pattern. S&DJR-pattern posts were erected with the rail web at right-angles to the track, while the SR type had the rail web parallel to the track.

The S&DJR-pattern rail-post signals had a cruciform finial, of which at least two designs are known, and also there were differences in the fixing arrangements. Some surviving finials have a single bracket projecting from the bottom, suggesting that it was located between two rails for bolting through, whilst others have a pair of brackets apparently to go either side of a single rail - these differences may be discernible in some photographs. The SR pattern had a low, pyramid-shaped finial. The rail-post signals built by the S&DJR had lower-quadrant (LQ) arms, although a few had upper-quadrant (UQ) arms in BR days; all the SR rail-built posts on the S&DJR seem to have had UQ arms.

For bracket signals the S&DJR design appears to have been similar to straight posts, although the dolls may have been only single rails - possible because of their short length or the need to reduce weight on the bracket. In the SR design the main post was often more substantial, with at least four rails, but the individual dolls were always lattice in order to reduce the weight.

In the late 1960s two examples of BR(WR) tubular steel posts were erected at Midford and a solitary example is known of a concrete post.

Lower quadrant signal
SR bracket signal with lattice dolls

Signal Arms

These were a LQ pattern similar to the L&SWR, although in SR days onwards UQ replacements appeared, usually with the distinctive corrugated arms. UQ arms were used mainly on the SR-type rail-built posts and on lattice posts; a few examples were known on the S&DJR-type rail-built posts, and only one on a wooden post. Stop arms were painted red with a vertical stripe on the front, white with a black stripe on the rear.

No specific information is available on the early style of distant arms but probably this followed the general British development. Originally identical to stop arms, from 1872 distant arms were distinguished by a V-notch cut in the end and later the white stripe was replaced by a white chevron; the rear appears to have retained a stripe even when the front changed to a chevron. From about 1925/7 onwards all distant arms would have been re-painted in the new standard of yellow with a black chevron on the front and white with a black chevron on the rear. Spectacle plates originally displayed red and white, but the white was replaced by green by about 1895. On distant signals the red aspect was superseded by yellow at the same that the arms were repainted yellow.

Subsidiary Arms

S&DJR 'Calling On' and 'Shunt Ahead' signals took the form of a full-size arm painted red with a white spot, surmounted by a black ring, the reverse being painted white with a black spot (PRSS Plate 81). In the SR period a few appear to have been renewed as a LQ arm, painted red with a broad horizontal white band and bearing a large 'C' or 'S' on their face; the reverse was painted white with a broad horizontal black band. In later years some were renewed as smaller UQ arms painted in the same style; some of these bore a large 'S' on their face while others had an indicator attached to the post which, when the arm was 'off', showed an illuminated 'C', 'S' or 'W' to denote their function ("Calling On', 'Shunt Ahead' or 'Warning'). In such cases the main arm was renewed also as an UQ arm.

For 'wrong direction' movements over running lines a particular signal was used which had a full-size arm in the shape of an elongated X, often referred to as a "bow-tie" arm. This pattern was peculiar to Stevens installations and was not unique to the S&DJR; although perhaps the most well-known aspect of S&DJR signalling, only about five examples in fact existed on the line (PRSS Plate 83).

"Bow-tie" signal arm

Ground Signals

These were originally of the Stevens 'flap' type (PRSS Plate 79), but from SR days onwards many were replaced by the standard SR Westinghouse 'half-disc' pattern (PRSS Fig 20) and there were also a few examples of the 'miniature semaphore' type used where 'yellow' arms were required (PRSS Plate 87)

Stevens' Flap ground signal


Southern "half-disc" ground signal

© C J L Osment 1998

Comments about this article should be addressed to Chris Osmont

Southern "miniature semaphore" yellow ground signal

Further articles about signalling in the West Country
will be found at Chris's Railwest web site

Drawings by John Hinson