This is an enforcement issue, not (just) an infra issue . States have to enshrine the right to free flow of traffic as a fundamental right and empower police to do what it takes to keep traffic moving - from ticketing jaywalkers to banning tractor trailers, carts, and livestock from roads outside certain time windows.
Signage has to improve too so that drivers aren’t forced to slow down or swerve to make an exit.
Just like swacch Bharat, make it a national priority to increase the average traffic speeds of arterial roads by 5% every year. Publish those stats. Imagine having a choice of moving to say Chandigarh vs Indore but picking one over the other because they average traffic speed of that city is 20% more.
Introduce the concept of laminar traffic flow and do PSAs on how one person making a selfish choice on the road leads to cascading effects downstream.