Underground City Highway System

Isn't it annoying having to stop at all those traffic lights on the way home? And then when you finally get there you can't find a place to park? Well, when you think about it, it can be avoided. Here's my idea: have an underground highway system that runs beneath the city. It would have an exit ramp on every block which would lead into a spacious parking area. what is now known at the "streets" would become this spacious parking lot with plenty of room to spare for walking malls, parks, greenery and playgrounds. This would solve the parking problem, as there would be more than enough room to park, and would make the city a much more pleasant place to live with the absence of cars driving on the surface. The only downside would be the drivers themselves who would now have to drive in a tunnel and would not be able to enjoy the scenery. But they would be more than compensated for with the quick ride and the scenic pleasant surface once they get there. An additional advantage would be that all underground things that require maintenance, (pipes electric etc) would be easily accessible through doors in the tunnel. Since there would be less confusion with traffic lights and stop signs and pedestrians, etc, there would be fewer accidents. It would be a little expensive to build but it would be worth it and the city would gain from the increased revenue as more would move in.