This page provides a Register of all the known electrical Track Circuits on the former Somerset & Dorset Joint Railway (S&DJR).
It is not known if any official records survive which list all the S&DJR track-circuits (TCs). The information contained in this Register has been compiled by studying surviving copies of S&DJR signal-box diagrams, upon which usually any TCs were marked, and other railway documents. It is possible therefore that there may have been some TCs which were added not long before closure of the line in 1966, but for which updated signal-box diagrams do not exist to reveal their presence.
In the absence of any definitive records it is not possible to be certain exactly when the S&DJR started to install any TCs, but it is probable that the first example was at Midford, where one is known to have been in use by late-1923. There was not a large number of TCs on the S&DJR and indeed almost a third of them existed at only one signal-box, Templecombe No 2 Junction, after it took over the work of Templecombe No 3 Junction in 1933. Almost all the other signal-boxes with TCs had merely one or two each. Several of the TCs were added during the British Railways era as a result of maintenance work on facing points, when the mechanical locking-bar component of the Facing Point Lock mechanism was replaced by a TC through the points which controlled an electric lock on the FPL lever.
TCs were identified simply by letters, a separate sequence 'A' 'B' 'C'... etc being used at each signal-box. There were exceptions at Evercreech New, where there were four short TCs (two on each line) provided for the purpose of operating a warning bell at a foot-crossing; these TCs apparently had no signalling function and did not appear on the signal-box diagram, so it is not known how they were identified. It should be noted that at some locations which had both track-circuits and treadles a single sequence was used for both types of equipment, whereas at other locations separate sequences were used for the different types.
The status of a TC - 'clear' or 'occupied' - was indicated in the relevant signal-box by means of an electric indicator mounted on the instrument shelf above the lever-frame. Only in one signal-box (Templecombe No 2 Junction) was the practice adopted of providing an 'illuminated' signal-box diagram (which incorporated lights to show the TC status in the relevant parts of the tracks marked on the diagram) and this was not provided until about 1953 to replace the existing indicators.
The Track-Circuit Register entries are listed in the line order of the various relevant signal-boxes, but an alphabetical Index to Locations is provided also for quick access to individual signal-boxes.
The following explanations of Track-Circuit Register entries should be noted:-
|Index to S&DJR Track Circuit Locations|
|Blandford||Evercreech Jcn South||Midford||Sturminster Newton|
|Burnham||Evercreech New||Midsomer Norton||Templecombe No 2 Jcn|
|Corfe Mullen Junction||Glastonbury||Radstock West||Wells 'A'|
|Edington Junction||Highbridge Loco||Shillingstone|
|Evercreech Jcn North||Masbury||Stalbridge|
|Somerset & Dorset Joint Railway Track-Circuit Register|
|Midford||A||circa-1923||On Down line from heel of points 8 and extending beyond Down Advanced Starting signal 4, total length 1000 yards.|
|B||1952||In advance of Down Starting 3 through FPL 7 and facing point 8 to abut to TC 'A' on Down line and equivalent location on Up line.|
|Radstock West||see Note|
|Midsomer Norton||A||BR period||On Up line in rear of Up Advanced Starting 13, as far as (but not through) east crossover point 7.|
|Masbury||A||1928||On Down line in rear of Down Advanced Starting 4, as far as disc 12. (New siding connection and GF in Nov 1928.) Abolished 24-Sep-1959 (after abolition of Down Sidings and signal 4).|
|Evercreech New||by 1960s?||Four un-labelled short TCs, two each on Up and Down lines. One near Distant signal, the other a short distance in advance of station footpath crossing. (Provided to work crossing warning bell, replacing previous treadles, but not marked on SB diagram.)|
|Evercreech Jcn North||A||post-1930, by Dec 1949||On Up Main in advance of Up Homes 26PULL/26PUSH, through trailing points 19, FPL 17 and facing points 16.|
|B||On Branch single-line from 250 yards in rear of Down Home 4, past Up Advanced Starting 20 as far as disc 13PUSH.|
|Evercreech Jcn South||A||by 1930||On Down line in rear of Down Starting 5 as far as disc 13PULL.|
|B||by mid-1949||On Up line from level-crossing, past Up Starting 20 until level with disc 15PULL. (Extended further southwards in 1957 to abut to new TC 'C'.)|
|C||1957||On Up line in rear of Up Home 21.|
|Templecombe No2 Jcn||A||
|On Up Main in rear of Up Starting 9 as far as discs 3PUSH/7. (Extended back to signals 23/24 after crossover 14 abolished late-1957.)|
|B||On Up Main in advance of Up Starting 9 through trailing end of crossover 39 to disc 40.|
|C||On Up Main in rear of Up Advanced Starting 41 as far as disc 40 and in advance for 200 yards overlap.|
|D||On Down Main beginning in rear of No3 Jcn Intermediate Down Outer Home 29 and in advance as far as No3 Jcn Intermediate Down Inner Home 28. (Operated 10-second audible warning.)|
|E||Down Main in advance of No3 Jcn Intermediate Down Inner Home 28 through trailing end of crossover 39 and facing point and trap 38 as far as Goods Up Starting 36/37, and to equivalent location on Down line.|
|F||On Goods line (single) between Goods Up Starting 36/37 and discs 33/35.|
|G||On Good lines in advance of discs 33/35 through points 34 as far as discs 21 and 32.|
|H||1948?||On Up Line through FPL 15 and up end of crossover 14 only. (Abolished after crossover 14 abolished in late-1957.)|
|J||post-1948, by May 1953||On Down Main in advance of Down Inner Homes 25/26, through trailing end only of crossover 12, FPLs 10 and facing point 11, as far as disc 30PUSH and Up Branch Inner Home 6.|
|K||post-1953, by 1958||On Up Line through FPL 13 and up end of crossover 12 only.|
|Stalbridge||A||1955?||In advance of Down Home 2 through facing points 6 as far as Up Starting 13 and equivalent location on Down line. (Provided when point 6 motorised in Sep 1955?)|
|Sturminster Newton||A||Through FPLs 6, facing point 7 and facing end only of crossover 8, as far as Up Starting 14.|
|B||In advance of Up Home 15, through FPL 12 and facing point 11 as far as Down Starting 3 and equivalent location on Up line.|
|Shillingstone||A||by 1960?||In advance of Up Home 15 through FPL 13 and facing point 12 only.|
|Blandford||A||by Aug 1930||In advance of Up Starting 3, through (facing) point 20 and FPL 21 as far as Up Advanced Starting 4.|
|Corfe Mullen Junction||A||post-1933||On Down line in advance of Down Homes 2/4 through FPL 9 and down facing point 10 only.|
|Glastonbury||A||Through FPL 18, facing point 17 and point 16 (but not trap) as far as Down Starting 3.|
|Edington Junction||A||1948/49||Through FPLs 22 and points 21 and 23 (single-line end) only.|
|Highbridge Loco||A||Through FPLs 5 and points 6 and 25 (not trap) only.|
|Burnham||A||In advance of Up Home 2, through Loop facing point and trap and both FPLs, as far as (but not through) point A into sidings.|
|Wells 'A'||A||In advance of Up Starting 25/27 through FPLs 22, point 21 (facing end only) and point 17 only.|
Note: it is possible that there was a TC at Radstock North 'B' (formerly Radstock West) in the 1960s. There used to be a treadle (which worked a warning buzzer in the signal-box) on the Up line in rear of the Up Distant 31, but the depiction of this on a 1964 BR(WR) diagram is in a form which suggests that it may have been replaced by a TC by that time. At the moment its status is unconfirmed.
© Chris Osment 2013
TC indicators photograph courtesy Ian Matthews