Rebuttal to your post: 1. Many Asian cities have elevated pedestrian walkway systems. 2. Helsinki has underground pedestrian malls/tunnels. 3. Toronto's first PATH pedestrian tunnel was built before the post WW2 car culture explosion. 4. Toronto's winter cycling volumes are less than 10% that of the summer cycling volumes. Real statistics say that winter weather greatly affects people's decision on transportation mode.

I have used a couple pedestrian tunnel/bridge networks extensively in frosty Canadian winter climates, I really appreciate them plus I think they are a fun way to get from place to place - being able to travel at a different layer than street-level feels refreshing/novel!

I prefer to have better designed cities and to use of tunnels/walkways when there is no better alternative. In Asia, the walkways usually exist for wide roads that are in themselves not very friendly for the eyes, nor ears.

The newest parts of Shenzhen are bare deserts with wide roads with cars and emptied of people. Their tunnels are full of restaurants, shopping malls and young people enjoying themselves. But all that is illuminated by artificial light. Not the worst kind of city, but so much worse than to have all people and activity at surface level like Paris or London.

I agree, thou, that to have tunnels is an advantage during winter for cold countries. But as soon as the sun shines, I want to be outside getting as much sun and light as possible. Tunnels should not be a substitute to walkable cities but they can be a great addition.