Why the loop isn't a circle

DRAFT

If you asked a designer to draw the beltway around a city, you would get a circle. If you asked a highway engineer in 1960s Ohio, you would get 270. Two different jobs.

The east bulge

The eastern side of the loop swings out farther than the west. That is Easton, John Glenn International, and the ridgeline the road takes to skirt Alum Creek. Building the ring closer in would have meant condemning more of what was, at the time, small farms and orchards on the east side. Instead the engineers took the long way around, and the airport ended up inside the loop by inches.

The flat north side

The north run, from Sawmill east to Cleveland Avenue, is close to a straight line. That is because the Olentangy and Alum Creek valleys are shallow up there, and the corridor between Worthington and Westerville had room. Nothing pretty, but geometry does not always reward the map.

The southwest cut

The 71 interchange at Grove City is the sharpest bend in the ring. 270 south comes off the hill and hooks northeast to catch 71 before it crosses the Scioto. The corner is tight because there was already a rail line there and the freeway had to thread between the tracks and the river.

The moment you round any of these corners into a smooth arc, you lose the reason the road bends at all. The mark keeps them.