Something you city dwellers should get a hold of is a good map of the rail systems in your area. I procured one for my brother....and if they must hoof it.....the railways will be much less traveled than the roads....until they get out of the city.

Also there are a lot of berms and cover areas....not to mention fences to keep folks out of rail areas. If you move quickly....the idea of "OFF LIMITS" will still be in the minds of a lot of evil doers.