Some say it is folklore other not. But the story is that one in five miles of interstate are built straight and flat to serve as an emergency runway in times of war. Rather that is true or not I don't know. I do know that part of the big push for the interstate system from Eisenhower was to be able to move troops quickly from place to place. This purpose, I beleive was the reason for the Autobahn.
Was in East Germany just after the wall came down and there are/were areas where the central reservation was fully covered with the barriers in; thus (I assumed at the time) that these could be removed easily and thus provide extra run-ways.....
