Instead of trying to jam squishy humans along side aluminum vehicles, why not build elevated walkways above traffic? In a city, the space between buildings can

Instead of trying to jam squishy humans along side aluminum vehicles, why not build elevated walkways above traffic? In a city, the space between buildings can be auctioned, and the owner of that space is responsible for cleaning and policing a section of elevated plaza. The second story of each building can then be used as a storefront and events can be held in between buildings. If even a few blocks in the center of a city can be walkable above the traffic, I think it could create a popular tourist hub where people can explore the city, see events and spend money. Who foots the bill for construction, maintenance, and inspections which ought to be thorough and frequent, that’s another question I hope somebody who knows politics can answer.