On Tuesday, 20 March 2018 12:48:33 UTC, Basil Jet wrote:
Geoff's latest video...

https://www.youtube.com/watch?v=2aP2rMRO_WA

... shows a couple of WHISTLE boards in the vicinity of the Watford Met
Branch triangle. Why are these locations singled out for whistling? How
many whistle points exist on the tube? Wouldn't a fixed whistle
activated by the presence of a train be a better solution?

I am happy to be corrected but I believe WHISTLE boards are installed at points where there is an official crossing of the tube tracks. Often these are in depots or on their approach tracks but the few others are in more rural spots where a footpath may cross the tracks.

I suspect making it an instruction for the driver is to raise awareness and to ensure it is made. Having a remote activation may fail or be vandalised in situ and with no instruction to the driver an accident may ensue. I believe it is compulsory for the train whistle to be tested before a train is taken into service thus improving the chance the whistle will sound when pressed. I haven't used "guarantee" here because there is always a remote possibility that a train whistle may fail while a train is in service.

As ever I am happy to be corrected if any LU train staff are reading and are more up to date than I am.

--
Paul C
via Google