What if there was a speed governor proportional to the weight of the vehicle, so as to cap the possible level of kinetic force? People driving monster SUVs and pickups would still be safe from collisions, but would have to travel much slower and/or be confined to specific lanes.
I don't recall including tractor trailers in my suggestion - the reason being that commercial drivers tend to be more safety minded, and in some cases are already routed to dedicated infrastructure.
