roads
- The Eisenhower interstate system requires that one mile in every five must be straight. These straight sections are usable as airstrips in times of war or other emergencies
- In Singapore, some of their highways can be converted to runways by removing potted plants from the median strip
- In 2007, a Hokkaido inventor realized different pitches could be created by cutting grooves into roads – the result? Melody roads as you drive on them
