Swindon MAS Stage 3
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Swindon MAS Stage 3 - Thingley Junction to Bathampton and Bradford Junction
The third stage of the MAS scheme concerns the Chippenham to Bathampton and Bradford Junction area, and is described in notice S.2503, planned to be implemented Saturday 25th February to Sunday 26th February 1967 on the main lines and from Sunday 26th February to Monday 27th February on the branch lines.
Corsham Signal box was taken out of use and its equipment recovered.
Melksham Signal Box was already out of use since 1630 on Friday 24th February under notice S.2502.
Continuous Track Circuiting (CTC) was installed between Thingley Junction and Bathampton Junction and Track Circuit Block (TCB) working applied.
At Thingley Junction, all the semaphore signals were removed. On the Down Main, existing signals T50R and T50, installed in Stage 2, were renumbered T52R and T52. T52 was given a number 1 position light junction indicator, applicable to the Melksham branch, and no more signals intervened between there and the facing junction (the semaphore Inner Homes were not replaced). The Down Siding was also removed.
On the Up Side, the Up Main Home, was replaced as a 2-aspect colour light T3 (same lever as its semaphore predecessor). The functionality of the Up Main Distant (number 1, and only a single arm, reduced from 3 arms at the closure of Thingley West in 1955) was replicated in a new colour light T3R (Y/G), 2240 yards in rear. The Up Starting signal was not replaced.
The Up Sidings were retained, with a position light ground signal at each end of the trailing crossover connecting them to the Up Main. GPL T43 replacing semaphore disc number 43, and GPL T33 (normally showing yellow/white) replacing several ringed-semaphore arms reading from the various sidings (numbers 8, 16, 17, 33). The long trailing crossover from the sidings to the Down Main, with a fixed diamond in the Up Main was removed (lever 28).
An additional signal was installed on the Down Main, west of the junction, DM97 (2A). This was semi-automatic as it protected Corsham ground frame. [Released from Bathampton??]
The branch line, to Bradford Junction, was singled, the Up Branch, and associated fixed diamond in the Down Main and trailing point in the Up Main were all taken out of use. The Down Branch became a single line, up trains, leaving the branch, using the new trailing crossover installed in Stage 2 to access the Up Main.
Lever 7 (formerly a signal in the Up Sidings) was recycled to control two-aspect Distant and Home signals coming off the branch, T7 and T7R.
The block working on the branch became Electric Token Block between Thingley Junction and Bradford Junction, with the signals protecting the single line being released by withdrawal of a token for 'one train' (as opposed to 'one pull') only.
At about the 98 1/4 mile post the formation swapped sides. Trains from there to Thingley Junction travelled over the former Down Branch, and trains from there to Bradford Junction travelled over the former Up Branch.
New ground frames were installed to work siding connections at Melksham and Holt, released by the single line token. Intermediate instruments were provided at both ground frames, with telephones to Bradford Jn.
Although not on the Swindon panel area, as part of this stage of the scheme two auxiliary machines were provided at Bradford Junction at the Down Loop Starting and Up Branch Home (telephones to Bradford Jn). The loop between the Main and the Branch at Bradford Junction was also singled, the original Up Loop surviving to become bi-directional.
Back on the Main Line a new ground frame was provided at Box, to work a trailing crossover, protected by semi-automatic signals DM101R, DM101, UM101, UM101R. The existing connections at Corsham were worked by a ground frame, protected by UM101/UM101R on the up, and DM97 on the down.
Box GF and Corsham GF were locked by Annetts keys released from Bathampton Jn Signal Box, which also received telephone calls from UM101, DM101 and DM97.
Tell-tale wires already existed in Box Tunnel, these now being connected to Thingley Junction Box (pending the installation of emergency telephones "at a later date"). The siding connections into the east end portal of Box Tunnel were spiked, clipped and padlocked normal.
