Diamond interchange

[2][1] Because roundabouts can generally handle traffic with fewer approach lanes than other intersection types, interchange construction costs can be reduced by eliminating the need for a wider bridge.

An example in Canada is found on the Pat Bay Highway in North Saanich, British Columbia, near Victoria International Airport.

One such interchange exists at the junction between the Ruta Interbalnearia and Route 35 North near La Floresta, Uruguay (34°44′58″S 55°40′39″W / 34.7495°S 55.6775°W / -34.7495; -55.6775).

Several interchanges similar to those along Keystone Parkway are being built along the new US 31 freeway under construction in northern Indiana.

Some examples are at exit 38 of the N7 road in Groningen, Netherlands (at 53°12′53″N 6°36′09″E / 53.21462°N 6.602509°E / 53.21462; 6.602509); and Ennis Avenue (National Route 1) at Safety Bay Road (State Route 18 / Tourist Drive 202) on the border of the suburbs of Waikiki and Warnbro in the City of Rockingham, Western Australia (at 32°19′29″S 115°46′01″E / 32.32486°S 115.76704°E / -32.32486; 115.76704).

Such a design is found in Perth, Western Australia, between Roe Highway (State Route 3) and Berkshire Road (at 31°58′10″S 116°00′04″E / 31.96945°S 116.00107°E / -31.96945; 116.00107).

[1][7] This spacing forces the turn lanes for each direction to run beside each other, causing the minor road to be wider than it would be if it were a standard diamond.

[8] A single-point urban interchange (SPUI) is built with a large over- or clear underpass providing space for a single traffic signal controlled intersection with the ramps and the cross street.

In a three-level diamond interchange, the cross street is built in a third level with free flowing traffic as a second arterial road.

[11][12] A two-leg CFI, also in San Marcos, was built in 2015 at the intersection of Hopkins Street (State Highway 80), I-35's frontage roads and I-35's Texas U-turns.