As you can see in this save: http://list.extended.simutrans.org/~vladki/debug-saves/demo-8.sve
Directional reservations made by bidirectional track-circuit signals go too far beyond one-way sign.
Pause the game after loading. You'll see a train at Eastham, heading for Newtown, but waiting for clearance even though the platform it is heading to is clear. It will start only at the moment when the train from the opposite direction enters the loop, and track can be directionally reserved ahead of the loop.
If you continue watching, the train leaving the loop towards eastham will first make the blue reservation properly - only up to the one way sign at Underground station (use sliced underground view). But then after leaving eastham, it will make a directional reservation all the way to West Yard. I think it should not do that.
Thank you for the report; I think that I have managed to fix this. Would you be able to re-test? I should be most grateful.
Seems to be fixed, thank you