The university I went to invested in skywalks to replace many if almost all cross walks within and on the edges of campus. It does require more energy to go up and down sometimes, but it means everyone is safer and everything still flows.
- Empty streets feel less safe
- Stores get less foot traffic
- Cars are more likely to speed when there's no one walking about
The cost of that is immense. Why not just make the surface (ground level) street more accessible to pedestrians, and keep the businesses where they would prefer to be?
Aren't there large parts of Chicago already like that?
Chicago is also somewhat of an exceptional city in this regard in that it was to an extent demolished and rebuilt twice, and the city was further built up from water level to accommodate underground plumbing and (IIRC) to reduce the swampiness of the land.
You're not going to put them at every crosswalk
The university I went to is not like the one I see in Madison or Chicago. The entire campus was self contained and did not have non-university buildings there. So not much car traffic through the actual campus (as there were few roads, although the walkways were wide enough for maintenance vehicles to get around).
We have a '+15' system in downtown Calgary such that most of the core office towers are connected on the second floor. Parts of the first two floors of most buildings are open to the public, and tend to be commercial space.
Reading the Wikipedia page, it seems some people have been wondering if they're making the streets less vibrant, but quite frankly even if they were, the enclosed walkways would still be worth it for winter. It can get brutally cold on the Canadian prairies.
My walk to work was about 3.5km, half of it inside. Winter? What winter! I laugh at your winter!
In contrast, I live in Edinburgh. The all-time high temperature was around 30 celsius, but it only drops below freezing at night during a couple of months. The city predates the automobile; as a result, unless you move out to the suburbs, it's entirely walkable. And guess what? The Council is currently holding a consultation on a blanket reduction in the vehicle speed limit to 20mph except on designated high-volume routes.
That town also had a problem downtown of people that would cross the street without looking, and glaring at people driving cars. Pretty much the people posting in this thread lol.