Route signalling vs. speed signalling - an oversimplification?

[bécasse]

The wording and symbolisation (including the rather attractive signal posts) have been taken directly from my dye-line prints from the original linens. There had clearly been a number of alterations since they were originally signed off by "WHT" on 14.5.1914 but it was generally possible to see "ghosts" of what had gone before, and I suspect that the majority, if not all, of those alterations were made in the 1930s by the Southern Railway. There was no way of telling whether the linens originated at Wimbledon or in the DE Exeter's office, but circumstantial evidence suggests the latter. The DE Exeter (and the DE Glastonbury until that was merged into Exeter) was notorious for doing his "own thing", nevertheless I would expect the original linens to reflect the LSWR's general guidelines for the production of signal diagrams including the use of wording. It is clear that, at that period, the LSWR used only the lock symbol for FPLs even though they were fitted with bars. (I have seen photographic evidence that the FPL worked by DJ 8 had a bar on the Wenford line, and, indeed, the 1966 Reading-produced diagram for DJ shows a bar.) It is therefore impossible to tell from the linens whether the points worked directly by BJ box were originally fitted with bars or whether track circuit A was installed at the time of the 1914 alterations and fulfilled the same function electrically. However, the LSWR was already making significant use of track circuits by 1914 so I suspect that track circuit A dates from that year. The SR would only have installed the track circuit if it saved money - they did, though, move several dummies when Westinghouse discs replaced the LSWR Stevens flaps.

 

Three other points of interest about the layout generally.

 

Firstly the linens clearly show the original layout of p&c at the Bodmin end of siding no.1 and, because the points were then staggered (not tandem) there was a second dummy, however the points were later altered to a single true Y where each point blade was worked by a different lever (which in turn was released differently, either mechanically from BJ box or by the Bodmin North line tablet) thus providing a wide-to-gauge trap point when neither route was set. The linens weren't altered to show precisely this alteration (but photographic evidence exists) but schematically there is little difference.

 

Secondly the BJ box worked "from Wadebridge" dummy is most unusual in not only being worked by two separate levers depending on the route set but also being slotted on the ground by two different ground frames. I doubt whether this was a unique example on the Southern Railway but it must have been very rare.

 

Thirdly, in the early 1960s at least the layout was used to pass two passenger trains despite the lack of a passenger loop. The afternoon school train from Wadebridge to Bodmin General was accepted on to the Bodmin North (ex-SR) line under the 3-3 blocking back arrangement (since it had to shunt forward of the home signal for that line) so that a Bodmin General to Wadebridge train could pass on the ex-GW line, the school train then shunting back towards Wadebridge and then continuing in the usual manner to Bodmin General. Again this arrangement probably wasn't unique, although I know of no other example on the Southern.

Edited June 3, 2023 by bécasse