Cloverleaf Interchange

A cloverleaf interchange is a junction where two highways cross at different levels and connect entirely through curved ramps rather than a single traffic signal, so that a left turn is handled by continuing straight past the crossing road and then curving back through a three-quarter, 270 degree loop ramp onto it. The Maryland civil engineer Arthur Hale patented the design on February 29, 1916, and the first cloverleaf built in the United States opened in 1929 at Woodbridge Township, New Jersey, where the Lincoln Highway crossed Amboy Avenue, reportedly copied from a photograph of a Buenos Aires road junction that had appeared on a magazine cover. The design reached Europe in October 1935 at Stockholm Slussen interchange and Germany Schkeuditzer Kreuz followed in 1936, and the type became one of the standard interchange forms of the twentieth century growing highway networks even though its long loop ramps use considerably more land than later stack designs.