That's something I haven't thought about, but I 100% agree that it should be possible! Very soon I want to introduce roads with bicycle lanes, that have less car bandwidth, that will make me refactor the traffic simulation and the idea of a bicycle-only road type will become possible.
In Venice (the Italian one) - cars, mopeds and bikes are all banned. Most trade goods are transported around by a man moving fast with a sack truck shouting 'Attencion!'
