One of my favorite topics, because being prepared provides a measure of personal control in our individual sliver of a larger situation that will be beyond our control.
For many in D.C. and NYC on September 11, 2001, "get home" by foot became more than a logistical planning exercise. A lot of my girlfriends, in particular, cursed their choice of footwear that day (heels, of course). They kept sneakers at their office afterward but I'll bet many have gotten out of the habit as 9/11 memories fade.
I've lived within a mile of work for a couple decades so this has not been a pressing personal concern. But I have considered that something could happen when someplace other than work and because of where I live it may not be possible to drive home because of bridge or road closures. On the evening of 9/11, I thought about going out to Arlington, VA to visit friends but ultimately did not because of rumors that it might not be possible to get back over the bridges. So my vehicle is well-equipped for an overnighter and with a backpack (and hiking boots, socks, trekking poles, etc....). Some suggestions for a "get home" bag:
shoes/boots/socks/
map
headlamp + extra batteries
first-aid
cotton bandanas
N-95 mask
AM-FM radio + extra batteries
Leatherman
hiking pole (I have one with a cane-type handle)
cash
Sharpie + note pad
water
energy bars
lawn-garbage bag (emergency poncho)
Should go on some day hikes with these items and gauge how long it takes to travel the distance you may have to in a crisis.
3 mph is a good walking pace on flat ground. If I lived further than 5 or 10 miles from work I’d be looking at keeping an old (but recently tuned) bicycle and bike tire pump there.