Tuesday 29th February 1916

The cloverleaf interchange (junction) was patented in the US by Arthur Hale, a civil engineer from Maryland. It is a two-level interchange in which left turns (in countries that drive on the right) are handled by loop roads (US: ramps, UK: slip roads). To go left (in right-hand traffic), vehicles first pass either over or under the other road, then turn right onto a one-way three-fourths loop ramp (270°) and merge onto the intersecting road.