Diamond interchanges are generally interchanges used to connect regular
roads to limited access roads, or
freeways. The road meets the freeway at roughly a ninety degree angle, passes under or above the freeway and continues out the other side. Ramps off and on each direction of the freeway are built parallel to the freeway, meeting the road at two intersections on opposite sides of the freeway.
Diamond interchanges are cheap to build and the most common form of freeway-roadway interchange. However, they generally do not scale to large volumes of traffic because of congestion at the street-level intersections. Because of this, busy boulevards and freeways are often upgraded to partial cloverleaf interchanges.