Just reading the DCC thread. Optical, of course !
If Lane change is so simple, and Scaley approach is optical, why not utilise Scaley track, Scaley changers with their inherent optical mechanism, power track firmly but without digital complication / expense ?
( For the routed boys, this could all be replicated fairly cheaply, keeping cars the same )
This available, cheapish solution, only then leaves the problem of signalling from controller to car for speed and lane change. Costs of digital track senders, controllers etc. avoided.
Now could optical be used for collision avoidance ?