Swindon MAS Stage 2
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Swindon MAS Stage 2 - Wootton Bassett West to Thingley Junction
Overview
The second stage of the MAS scheme is described in notice S.2501, which had published implementation dates of (2200) Saturday 3rd December to (2200) Sunday 4th December 1966 and was mainly concerned with the implementation of MAS and TCB between Wootton Bassett and Thingley Junction, in preparation for later migration to the Panel.
Detail
Chippenham East and Langley Crossing Boxes were closed and all the signalling removed. The junction at Thingley was altered in readiness for MAS with the removal of one of its facing crossovers and replacement with a trailing one (that would eventually form part of the junction with the Melksham line (to be singled).
Continuous track circuiting was installed a Track Circuit Block (TCB) applied between Wootton Bassett West and Thingley Junction. Wootton Bassett West (working absolute block to East) thence lost its ability to switch out.
Note that the location "Wootton Bassett West" referred to the Main Lines as well as the Badminton Lines, not just the Badminton Lines like it does today.
At Wootton Bassett
Wootton Bassett West Box lost its Up Main Distant and Home (and Wootton Bassett East’s Up Main Distant beneath the latter) were all recovered and replaced with colour lights, BW37R (Y/G) and BW37 (3A).
A runaway catch point that had existed at 83m 77c in the Up Main was removed.
New Ground Frame at Christian Malford
A new trailing crossover was also installed at Christian Malford working a trailing emergency crossover, protected by semi-automatic signals UM90R and UM90 on the up and DM89R and DM89 on the down, all 2-aspects. The telephones on the signals and the release on the Annetts key for the ground frame were connected to Thingley Jn SB.
Langley Level Crossing
Langley Level Crossing was converted to automatic-half-barrier operation. The indications of the operation of the crossing and telephone communication were provided in Thingley Jn SB.
New Ground Frames at Chippenham
New ground frames were brought into use to work the remaining siding connections at Chippenham. Chippenham Up Siding Ground Frame worked a trailing connection in the Up Main, just east of Chippenham station, formerly number 29 in Chippenham East Box. Chippenham East Ground Frame, worked a second trailing connection in the Up Main further towards Swindon, formerly number 15 in Chippenham East, and also a trailing crossover between the main lines, formerly number 18 in Chippenham East Box. Chippenham Down Siding Ground Frame, worked a trailing connection in the Down Main, just east of the station, formerly number 46 in Chippenham East Box. All the ground frames were locked by Annetts keys in instruments released from Thingley Jn and telephones were provided.
Chippenham East SB had had a further ground frame within the sidings for access to the Westinghouse works. As part of this stage, the ground frame was reduced to 'ground lever' status, the key for its Annetts lock being held by the shunter, there being no signals reading over the points, no interlocking was required.
At Thingley
Thingley Junction lost its Down Main Distant and Home, the functionality being replaced by two new colour lights, T50R (Y/G) and T50 (3A), respectively. The diagram in the notice shows the next semaphore signals as the splitting signals for the facing junction (49/46 in Thingley Junction Box).
The notice does not make mention of the fate of Thingley's Down Main Intermediate Homes, but they are not shown on the notice, and the facing crossover they protect is explicitly detailed as removed as part of this stage. It is unknown, therefore, whether the Intermediate Homes were removed as part of this stage, or previous to it.
Multiple Aspect Signals
On the Up Main, the order of infrastructure was:
| Thingley's Up Advanced Starting | Semaphore | with telephones to Thingley Junction SB. |
| Chippenham Up Siding GF | ||
| Chippenham East GF | ||
| Langley AHB Crossing | ||
| UM.90R | (2A, Y/G) (no phone) | |
| UM.90 | (2A, R/G, semi-automatic, protecting Christiam Malford GF) | |
| Christian Malford GF | ||
| BW.37R | (2A, Y/G) | (No phone) |
| BW.37 | (3A) | with telephone to Wootton Bassett West SB. |
On the Down Main, the order of infrastucture was:
| Wootton Bassett's Down Main Starting | Semaphore | with telephone to Wootton Bassett West |
| DM.89R | (2A, Y/G) (no phone) | |
| DM.89 | (2A, R/G, semi-automatic, protecting Christiam Malford GF) | with telephones to Wootton Bassett West |
| Christian Malford GF | ||
| Langley AHB Crossing | ||
| Chippenham Down Siding GF | ||
| T.50R | (2A, Y/G) | |
| T.50 | (3A) |
Reference Material
| Swindon MAS Stages | ||||||
|---|---|---|---|---|---|---|
| Stage 1 | Stage 2 | Stage 3 | Stage 4 | Stage 5 | Stage 6 | Stage 7 |