Strange signals

[Deleted]

I noticed just outside of Chalfont & Latimer 2 stop signals very closely spaced to each other and I thought why are they so close to each other. 
What is the purpose of them so close together?

[Deleted]

JT83 and JT83 co-acting - for the Chesham single line.

[rincew1nd]

JT83 regulates entry to the Chesham branch, and is held at red until it been proved that a train has exited the section (AIALTB). JT83(Co-A) is provided as it is absolutely essential that a train does not pass the signal at red, I suppose similarly so to how buffer stops are provided with more than one red light - it's not just "Stop - Danger" it's "Stop - Peril".

[Deleted]

I always thought the co-acting signal was provided because, back in the day, trains could approach from the bay and the northbound main and the co-acting signal improved signal sighting. Was that just a myth?

[rincew1nd]

Oct 5, 2014 18:56:02 GMT tut said:

I always thought the co-acting signal was provided because, back in the day, trains could approach from the bay and the northbound main and the co-acting signal improved signal sighting. Was that just a myth?

Well, I guess any co-acting signal is there to improve sighting. However in this case trains from both the main and bay travel along the branch line for a fair way before reaching JT83, so I don't see how either the main signal or the co-acting could provide improved sighting for a train from either origins.

[Deleted]

After googling, I gather that you are quite correct. DistrictSOM provides the answer here.

Always good to be disabused of a wrong answer =)