A cloverleaf interchange is a two-level interchange in which left turns (reverse directions in left-driving regions), are handled by ramp roads (US: ramps, UK: slip roads). To go left (in right-hand traffic), vehicles first continue as one road passes over or under the other, then exit right onto a one-way three-fourths loop ramp (270°) and merge onto the intersecting road. The objective of a cloverleaf is to allow two highways to cross without the need for any traffic to be stopped by red lights, even for left and right turns. The limiting factor in the capacity of a cloverleaf interchange is traffic weaving.