Yonah Freemark and Jebediah Reed at the Infrastructurist look at four major urban highways that were demolished, creating lovely waterfronts and parks. There is the Cheonggyecheon highway in Seoul, Harbour Drive in Portland, the Embarcadero Freeway and the Central Freeway in San Francisco.
In every case , the city was a lot prettier. What is surprising their claim that the traffic actually now moves better than it did before.
Embarcadero Freeway, San Francisco, before
The mathematical reason is called the Braess Paradox:
the addition of extra capacity to a road network often results in increased congestion and longer travel times. The reason has to do with the complex effects of individual drivers all trying to optimize their routes. Likewise, there is the phenomenon of induced demand — or the "if you build it, they will come" effect. In short, fancy new roads encourage people to drive more miles, as well as seeding new sprawl-style development that shifts new users onto them.
They come to a conclusion that should be listened to by many in those cities where waterfronts have been destroyed by highways:
The lesson is clear: If a major road is making a city a less livable and vital place that it would otherwise be, in many cases everyone benefits when politicians have the vision and guts to tear it down.