With limited amount of space available in tight urban areas, I wonder if elevators would be a good solution. The downsides include continual maintenance and upfront cost. But the reduced sprawl of random walkways seem worth the extra effort.
The bridge below is a quick example, obviously quickly sketched with no thought to member sizes, of a simple bridge system. I was even thinking that the elevators could be powered by solar energy in less urban areas.
What do you think?