When the American Eisenhower interstate system was constructed it was a specific requirement that one in every five of the 46,837 miles of road had to be kept perfectly straight. The idea was that during times of war the roads could be used as emergency runways, negating the need for more airports.
Actually, the 405 freeway in Los Angeles was designed as a backup runway for LAX airport. As far as I know it’s only been used for this purpose once, as documented in the documentary “405″ available at
http://www.405themovie.com/Home.asp.
This is what you are after...M55 photo.