I was thinking one would replace the tires with train wheels, so you keep the steering system intact. The biggest downside to doing exactly this is that car tra

I was thinking one would replace the tires with train wheels, so you keep the steering system intact. The biggest downside to doing exactly this is that car traffic will not have traction as most of their tire contact patch will be on the steel rails, rather than the pavement. Or even better, just buy off-the-shelf trolley busses, as they are cheap, and you need a fraction of the infrastructure.