Yes An no.
Yes it is already built.
No because there is a lot that can be done to improve existing infrastructure.
Public transport can be retro fitted rail corridors, dedicated bus lanes, bike only paths, walking infrastructure
Zoning can achieve a lot too. Allowing more commercial pepperpotted amongst residential
You do have to defeat many vested interests, but unless we defeat them they will burn the world for profit, so we must defeat them
A real test for democracy