According to this graphic from The Atlantic, the roads and highways in our metropolitan areas are packed beyond capacity and it's costing us billions.
The accompanying article says:
"...of the 6,373 earmarked projects that dominate the current federal transportation law, only half are targeted at these metro areas.
...To power our metropolitan engines, we need to make big, well-targeted investments that improve transportation within and around them."
Letting cars idle bumper to bumper is clearly a waste of time and gas. We just hope that new "big investments" in metropolitan transportation are more far-sighted than a 30-lane freeway. Trains, maybe?