[ghaff]

Yes. Basically you can't rapidly evacuate cities. Maybe highways help a bit but, if you can barely handle commuter traffic on a given workday, you're certainly not going to completely and quickly evacuate a city if there's some threat--and that's before you even get to the issue of people who don't own cars.

So the idea that highways would be useful if there were an imminent threat of nuclear attack looks pretty silly.

[bobthepanda]

It depends on how quickly and how far you need people to evacuate.

Lower Manhattan on 9/11 was evacuated mostly by foot and sea, with over half a million evacuated by boat alone: https://en.wikipedia.org/wiki/Maritime_response_following_Se...