TL;DR
Make station checkbox to block trains going though it without stopping.What ?
Train pathfinder should consider path through "blocked" stations only when it's the only way to reach destination (regardless of signals state, etc). E.g. you may have several "blocked" stations in a one line and a train may reach second stations only going through first. If there is another path available even very long or with busy signals the path though such station should never be an option.Why ?
This simplifies design decisions for single-headed train stops which create loop through which another train should never go.On the screenshot there are 2 1-directional ways at the bottom merged into a single 2-directional way going to the station and making a loop. If I place there only chain signals another train may still wait at the 2->1 branching to loop through the station.
See also viewtopic.php?f=5&t=29023