In article , zaphod writes:
OK, This sounded a little strange to me, but during lunch today with some
co-workers, someone asked if I knew of some rules regarding interstate
construction. They had heard a bit of trivia that claimed that an
interstate highway must have sections that are straight, level, and long
enough for a plane to land(at least 1 mile they thought.) I had never
heard of such and was wondering if anyone here knows what they were talking
about?


This gets debated fairly often, concensus is that it is an urban legend,
atleast in the States.

A repeating vector for this UL is provided by a guy from Harvard named
John Stilgoe, a "professor of ordinary things around us". He has several
times stated that not only are they designed for landings, but that SAC
often practices B-52 landings on Interstates - a notion richly poo-pooed
by folks who are in the know regarding all things SAC and B-52
.. He has stated this in an article in the "Smithsonian" a few years back,
and also on an interview done by National Publice Radio.

The date of the NPR show was July 2 1998. It was available in Real Audio format
at www.npr.org, the segment titled "Outside Magic", don't know if it's
still there.