Three-level diamond interchange
A three-level diamond interchange is a type of highway interchange where through traffic on both main roads is grade-separated from intersections which handle transferring traffic. It is similar in design to a three-level stacked roundabout except for its use of (usually signalled) conventional intersections, and can be thought of as two diamond interchanges fused together.
In a three-level diamond interchange, the two main roads are on separate levels, and on a third level, usually in the middle, there is a square of one-way roads. The square circulates clockwise where traffic drives on the left, or anticlockwise where it drives on the right. At each corner of the square is the terminal of an exit ramp from one main road and an entrance ramp to the other main road.
Traffic transferring from one road to the other to make an overall right turn only passes through one corner of the square, at which point a right turn is made. Transfer traffic making an overall left turn must proceed straight through the first intersection it encounters, turn left at the next, and then proceed straight through a third intersection to enter the other main roadway.
Three-level diamond interchanges are most common in urban settings where the right-of-way for a new interchange must be kept to a minimum.
|Location||First Route||Second Route||Notes|
|Cedar Rapids, Iowa||I-380||Iowa 100||Collector/distributor roads intersect.|
|Sioux City, Iowa||I-29||US 77||Being replaced with diamond interchange|
|Detroit, Michigan||I-75 (Walter P. Chrysler Freeway)||M-102 (8 Mile Road)||I-75 uses frontage roads|
|Detroit, Michigan||M-1 (Woodward Avenue)||M-102 (8 Mile Road)|
|Detroit, Michigan||M-10 (John C. Lodge Freeway)||M-102 (8 Mile Road)||Includes flyovers from northbound M-10 to westbound M-102, eastbound M-102 to southbound M-10, and westbound M-102 to northbound M-10. M-10 uses frontage roads|
|Redford Township, Michigan||I-96 (Jeffries Freeway)||US 24 (Telegraph Road)|
|Jefferson City, Missouri||US 50 / US 63 northbound||US 54 / US 63 southbound||A flyover ramp allows southbound US 63 traffic to join US 50 east, bypassing one intersection. The ramp from east 50/north 63 to west 54 is closed and motorists must use a nearby city street to make a such maneuver.|
|Asheville, North Carolina||I-240||US 70||I-240 exit 7|
|Marple Township, Pennsylvania||I-476||US 1||I-476 exit 5|
|Robinson Township (Washington County), Pennsylvania||Toll PA 576||US 22||PA 576 exit 6; partially completed, temporary terminus of PA 576|
|Waco, Texas||US 84||SH 6||Includes frontage roads at-grade with interchange|
|Alexandria, Virginia||I-395 (Shirley Highway)||Seminary Road||I-395 exit 4|
|Fairfax County, Virginia||SR 286 (Fairfax County Parkway)||US 29||The south end of West Ox Road also meets this interchange.|
|Welch, West Virginia||US 52 (King Coal Highway)||US 121 (Coalfields Expressway)||As of 2011, grading has been completed for interchange but interchange itself has not been constructed.|
|Wheeling, West Virginia||I-470||US 250 / WV 2||Entire interchange is elevated above city streets.|
|Wauwatosa, Wisconsin||US 45||WIS 190 (Capitol Drive)||An access road for the adjacent Harley-Davidson plant is also part of the interchange.|
|Belmont, Queensland, Australia||Gateway Motorway (State Route M1)||Old Cleveland Road (State Route 22)||Two of the ramps are two-way for a short distance to allow access from the interchange to and from local streets.|
|Düsseldorf-Stockum, Germany||Autobahn 44||Bundesstraße 8||At; rare design in Germany|
Many examples of this interchange type can also be found in Texas; however, the interchanges almost always include the frontage roads as well. If the traffic amounts increase the interchange is usually converted into a stack interchange, also as the second level of the High Five Interchange.
- Aerial view of a three-level diamond interchange (Interstate 380 and Iowa Highway 100 in Cedar Rapids, Iowa). Highway 100 runs from left to right; Interstate 380 runs from top to bottom.