This is what I was thinking. I believe the movie Her uses an ultra-dense future Los Angeles where the main (human) character lives and works in high-rises, and walks between them on elevated walkways[1] as the location. An elevated walkway that zig-zagged across the road and had stairs to the regular sidewalk once or twice a block seems like an interesting approach.

1: http://static.srcdn.com/wp-content/uploads/her-joaquin-phoen...

It's fairly common in Hong Kong's denser parts like Central. I was able to get around much of the heavily trafficed areas without needing to be at street level.