I seem to be having this problem too.
I tried all sort of combination but the trains AI will always try to use the shortest route, instead of parallel routes on multi-tracks lanes, with switch connections across all 4 or 5 lanes
Trains still jams up trying to use the first lane, even when a passing option is available to switch to the other lanes.
I’ll try to waypoints signals to see if it makes any difference, since traffic lights doesn’t seem to be doing much in that regard.