"Reinstated" - signal block section lengths...

[rkk01]

Are there any approximate "rules of thumb" for signal spacings?

Even for prototypical routes it can be difficult to determine signal locations from map / aerial photography references...
... Start adding new track to old trackbed and it gets a bit guesswork!

Would I be right in remembering circa 1800m, from a previous thread??? (For rural areas, no junctions etc - obviously closer in more complex areas)

[rosschris10]

signal spacings very on the following rules of thumb

Speed of the fasted train
weight of the heaviest train
gradient of track
and braking distance of the fastest train

there is no set rule in real world railways it is all calculated on the forms above

[JasVick]

There is a general minimum distance, which is as far as I can remember generally calculated to take in the type of train cleared to operate on it, also this takes in braking and gradients along with various other constraints which may conflict such as poor sighting.

I cant remember for sure but there was if I do recall a document on the raib website which also contains all the rule books. AWS magnets have a general distance setting but can also be affected by various factors.

[Carinthia]

Are there any approximate "rules of thumb" for signal spacings?

I'm not sure what kind of signal you are asking about - semaphore, colour-lights, three aspect, four aspect?

It depends very much on line speed and also on gradients. The key factor is to give a driver adequate distance to brake and stop safely at a red. I tend to use the following as a rough guide for minimum distances:
50 mph . . . . 0.5 mile
75 mph . . . . 0.75 mile
100 mph . . . . 1 mile
and so on. I add 0.1 mile for a falling gradient, more if it is steep.

You also need to take into account sighting - best to put a signal before a bridge rather than after.

I don't have too much experience of the 100 mph end as I tend to work with steam-era, if you find that a bit tight then add a bit extra.

The railways use complicated graphs to work each one out.

John