I once built a city in SC4 (almost) without traffic. Every building connected to a tiny square of road* encircling an underground station, the little island cities were connected in an underground network, with the industrial pockets at the edge of the map. I think there was one lazy f*cker who drove from his apartment building to the station across the road, but otherwise there were no cars. Until I built the city enough to get the hospitals, police stations and fire stations with air support, I left one square free at the corner of every pocket city to manually drive the emergency vehicles to a disaster.
*As in:
RRR
RUR
RRR