Combinators: Keep a Gete ope for some time after passing it

[Quax]

Hi all, I'm currently stuck at creating a safe railroad crossing. Recently, I placed some gate elements and set the signal to turn red once the gate is open. However, since the gate closes behind, the signal turns green again when you are still crossing the rails. Which bears some risk of getting steamrolled by a train.

I therefore want to keep the signal red for some seconds after the gate closes again. I already found out how to set up the timer that keeps sending the output signal to the rail signal (via looping back the output to the input). However I cannot figure out how to stop the timer after the first cycle. All I get so far is a decider combinator that runs through endless circles (from 1 to the limit set in the decider).

Any help is much appreciated

[BraveCaperCat]

Actually, A better solution might be to just only turn the signal green when both the entrance and exit gates are closed and have the signal be red otherwise.
Or I'm just misunderstanding what you're trying to do and it won't work for whatever reason.

[Quax]

Ok, so here's the problem. As you can see, the gate has already closed, and the signal would be green again, but I'm right on the tracks ... so I want the signal to stay red long enough for me to cross the whole track. I know there would be an easy solution to this problem by covering the whole crossing with gates .. but I would like to figure out a smart combinator-based solution, as I'm now starting to dwell into the combinator part of Factorio

[BraveCaperCat]

Ok, so here's the problem. As you can see, the gate has already closed, and the signal would be green again, but I'm right on the tracks ... so I want the signal to stay red long enough for me to cross the whole track. I know there would be an easy solution to this problem by covering the whole crossing with gates .. but I would like to figure out a smart combinator-based solution, as I'm now starting to dwell into the combinator part of Factorio

I see... I guess it's a bit more complicated then.
I'm not sure how it would translate into combinators, but you could check for one gate opening - when that happens, you'd turn the signal to red, then wait for the other gate to open and then close again. Once that happens, you'd turn the signal back to green.

[Quax]

I understand the underlying idea, but how am I supposed to tell the signal (or any combinator processing network signals) to wait for something?