[Green]

LOL My ex's father and brother are both civil engineers and one works for the state highway department...guess I could have asked him.

[Daniel Ramsey]

I recall I may have seen somewhere that fact and also I think it may still be used on aeronautical charts where the 3-mile zones are shown on the interstates for emergency landings, they must be straight, level, no immediate obstructions near the medians so large aircraft can land without the wings hitting stuff like power lines, streetlights etc.