Chapter 1360
Interchanges
WSDOT Design Manual M 22-01.20
Page 1360-3
September 2021
1360.02(2)(c) Cloverleaf
The full cloverleaf interchange has four loop ramps for the left-turning traffic. Outer ramps provide for the right
turns. A full cloverleaf is the minimum type interchange for a freeway-to-freeway interchange. Cloverleaf
designs often incorporate a C-D road to minimize signing difficulties and remove weaving conflicts from the
main roadway.
The principal advantage of this design is the elimination of all left-turn conflicts with one single-level structure.
Because all movements are merging movements, it is adaptable to any grade line arrangement.
The cloverleaf has some major disadvantages. The left-turn movement has a circuitous route on the loop ramp,
the speeds are low on the loop ramp, and there are weaving conflicts between the loop ramps. The cloverleaf
also needs a large area. The weaving and the radius of the loop ramps are a capacity constraint on the left-turn
movements.
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