"Set signal to automatic" question.

[NW1776]

How does this feature work? Curious on it's uses/limitations.

[DPump]

See here:
http://webrailroader.com/ctc/how-does-ctc-differ-from-tdp/, bullet "Automatic signals"

Just to complete the "Automatic route extension" term: if you lay in a route to a destination block, and if there is an automatic signal at the end of that block, another route to continue beyond that block is automatically created as soon as possible. So it may be that at certain times it is not possible to clear that signal because of conflicting movements or other conditions, but the system monitors the situation and clears the route when possible.

This "extension" is similar to TDP's fleeting signals. However, if in TDP a signal is set to fleeting, you cannot throw switches on the path past that signal, even though it may not be clear. You have to-unfleet, throw the switches and than you can fleet again. In CTC, when the route is not extended yet, you don't have a route. Hence you can throw switches as much as you want while the signal still shows "stop". In other words, TDP's fleeting signals predetermine the routes when passing that signal, while CTC's automatic signals with the route extension does not.

[NW1776]

I'm aware of the automatic signals, but I was wanting to wait til a train gets in the block to approach the signal

[DPump]

I think I have discussed it somewhere, just too lazy to search for it right now, so here is the idea (to be implemented):
A function can be added to the trigger feature that could stack a route for execution - immediately or once the path is free. If such a trigger is placed at the beginning of a block, it could do the trick.

With some enhancement that mechanism could be set up to set different routes depending e.g. on the train type.

Finally, with the superblock construct, the trigger can be placed just a brake distance away from the exit signal, if the (overall super-) block is very long and you don't want to set the path for continuation right upon entrance but sometime later.