Castle Cary blue signals

"Set Back" Indicators. Propelling movements made from the East end entering the "Up and Down" Loop line via position light signal W782 prior to running-round must be brought to a stand immediately the locomotive has reached the Taunton side of signal W249.

No further movement must be made until the Guard/Shunter has operated the plunger fixed to a post opposite the loop line station platform. Depression of the plunger illuminates three double-sided white light indicators, provided at intervals of approximately 150 yards beside the loop line. The Guard/Shunter must keep the plunger depressed while the lights are required to be illuminated. When the leading vehicle of the movement has reached the plunger post the plunger must be released. When the train is at a stand the Guard/Shunter must advise the Signaller.

The Driver may commence propelling as soon as the lights are illuminated. The movement must be driven from the leading (Taunton end) cab at a maximum speed of 3 mph, and the Driver must be prepared to stop the movement immediately the lights are extinguished.

Trains being propelled under these arrangements prior to running-round must not exceed 32 SLUs inclusive of locomotive (and brake van where provided). The indicator equipment must be in working order and the movement may only be carried out in clear weather.

In all other circumstances the train must run-round at an alternative location.

Idle curiousity - why is this set up needed here, but not in other similar locations?

The SA quote provided says that a train has to be brought to a stand immediately after the locomotive passes WN249 and is not to be moved until the driver sees the illuminated shunting light. But from the photo, a driver would not be able to see the shunting light (looking forwards) having stopped immediately after drawing past WN249.

These look relatively modern, what is the advantage of this over a pair of handheld radios and guard-to-driver instruction? Or even perhaps hand signals or fixed distance markers? You sometimes see stop boards for different train lengths in reversing sidings or locations.

Suggests at the time of resignalling Castle Cary into Westbury PSB - 1985.

Likely a concern that running round could propell too far and ACOA a train from Weymouth ? Before resignalling such a move would not be required / possible.
https://www.flickr.com/photos/187334503@N06/galleries/72157714135574817/

Thanks Bill, for taking the time.

I realise I made a geography error. I realise now when it says propelling from the Taunton end that the driver would be facing forward during the propelling part, and therefore able to see the shunting lights that are on the left.

I would rely on others for the commonplace nature of back to back radios in 1985 - I was not born for another few years.

The imperative for precision is made clear in the other part of your post. I assume this refers to triggering the signalling on the single line section to Yeovil. However, would the loco going to run round on the single line not trigger the same ACOA?

The lights at Lawrence Hill were for the propelling movement from the relief line into the Council Recycling Centre (dusty bins). Which no longer runs.

taffy in post 159514 said:

The lights at Lawrence Hill were for the propelling movement from the relief line into the Council Recycling Centre (dusty bins). Which no longer runs.

That format are usually shunting speed control signals, variously deployed in multiple colour / flashing variants....
http://www.railsigns.uk/sect10page1.html
and following pages.

The common themes are 'stop', 'slow speed to load/unload' and 'proceed normally'.