Here's a thought - dont do anything at all !
Let the roads continue to clog up until by natural churn people start to use alternative forms of transport.
What I mean is, we make a decision to use the car because we tolerate the 'congestion' on our journey... however, there will come a point where individually, or corporately, we decide we cant tolerate it any longer and either go via some other means or not at all. Over time, traffic will find a natural level and adjust itself accordingly.
Simple rule of supply and demand.