why is my train stopped at a green chain signal?

[Mauslag PIngman]

Doesn't a green light mean go?

This is the simplest thing in traffic. If the light is green, that means the vehicle looking at the green light can go. If the light is red, the vehicle should stop, but in factorio the train looking at a green light stops. What is the point of having red and green lights if they don't mean anything?

[Zanthra]

When mousing over the green chain signal in question, is it on the same track and signaling to traffic in the same direction as the train in question? If so, and the train is not stopped for another reason (in manual mode, out of fuel, cant find a path, or stopped at another signal or station very close to the chain signal). Then it sounds like a bug. Either the signal should be blue or red, or the train should be going. A chain signal will only be green if all exit blocks after the signal in that direction are clear.

[JimBarracus]

Doesn't a green light mean go?

This is the simplest thing in traffic. If the light is green, that means the vehicle looking at the green light can go. If the light is red, the vehicle should stop, but in factorio the train looking at a green light stops. What is the point of having red and green lights if they don't mean anything?

I bet you have some difficulties with seeing colors. Maybe you don't know it yet but chain signals can be green, red and blue.
Blue means that a part of the possible paths is free but not all paths are free.
Your train wants to take a blocked path and waits at the first chain signal like intended.

[Zavian]

I suggest posting a screenshot or the savegame. otherwise all we can do is guess at the cause.

[Aeternus]

Trains should not stop at a green signal, however:
- If it doesn't have a route to it's destination (due to deconstructed/destroyed rails or a deactivated/missing station) it'll stop in place. The train will periodically float a "No path found" text in red above the engine to signal this.
- If a train lost a car due to a collision or biter activity, it'll automatically come to a full stop. It will switch to manual.
- If the train is set to Manual for some reason, it'll not move by itself at all, regardless of signals.
- A signal with a circuit connection has 2 "lights" on it, the signal lights and the yellow box for circuit control. Make sure you're looking at the correct light in that case.
- Signals placed on the wrong side of the track will block the train. Signals are one direction only unless you place them on both sides of the track at exactly the same track section across the entire path.

[Jap2.0]

Yes, screenshot or save please. Without that all we can do is speculate.
(on the note of speculations, either the signal is not green, it's on the wrong side of the track, or there isn't a path)