Trains still jams up trying to use the first lane, even when a passing option is available to switch to the other lanes.
Trains in TF will never ever stray from the assigned line. If that is occupied, they wait. There is no such thing as switching to a free track. If you want them to run on another track, you have to use signals or waypoints to force the whole line (in one direction) on the desired track. Trains serving that line will then use that track – exclusively.
Trains do not switch tracks dynamically, period. 🙂