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.
Its two-level variant is the split diamond interchange.
Its at-grade variant is the town center intersection (TCI).
|Location||First Route||Second Route||Notes|
|Cedar Rapids, Iowa, United States||I-380||Iowa 100||Collector/distributor roads intersect.|
|Detroit, Michigan, United States||I-75 (Walter P. Chrysler Freeway)||M-102 (8 Mile Road)||I-75 uses frontage roads|
|M-1 (Woodward Avenue)||M-102 (8 Mile Road)|
|M-10 (John C. Lodge Freeway)||M-102 (8 Mile Road)||Includes slip ramps 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, United States||I-96 (Jeffries Freeway)||US 24 (Telegraph Road)||I-96 uses frontage roads|
|Jefferson City, Missouri, United States||US 50 / US 63 northbound||US 54 / US 63 southbound||A flyover ramp has been added to allow westbound US 54 traffic to join US 50 east, bypassing one intersection. This addition necessitates the use of a nearby city street to transfer from westbound US 50 to westbound US 54.|
|Asheville, North Carolina, United States||I-240||US 70||I-240 exit 7|
|High Point, North Carolina, United States||I-74 / US 311||I-85 Bus. / US 29 / US 70||I-74 exit 71B|
|Oklahoma City, Oklahoma, United States||SH-74||Kilpatrick Turnpike||A flyover ramp has been added to allow westbound Kilpatrick Turnpike traffic to join State Highway 74 south, bypassing one intersection.|
|Marple Township, Delaware County, Pennsylvania, United States||I-476||US 1||I-476 exit 5|
|Robinson Township, Washington County, Pennsylvania, United States||PA Turnpike 576||US 22||PA 576 exit 6; partially completed, temporary terminus of PA 576|
|Frisco, Texas, United States||SH 121 Toll||SH 289||Includes frontage roads at-grade with interchange|
|Richardson, Texas, United States||US 75||Spring Valley Road||Includes frontage roads at-grade with interchange|
|Round Rock, Texas, United States||US 79||SH 130 Toll||Includes frontage roads at-grade with interchange|
|Sherman, Texas, United States||US 75||US 82||Includes frontage roads at-grade with interchange|
|Waco, Texas, United States||US 84||SH 6||Includes frontage roads at-grade with interchange|
|Alexandria, Virginia, United States||I-395 (Shirley Highway)||Seminary Road||I-395 exit 4|
|Fairfax County, Virginia, United States||SR 286 (Fairfax County Parkway)||US 29||The south end of West Ox Road also meets this interchange.|
|Welch, West Virginia, United States||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, United States||I-470||US 250 / WV 2||Entire interchange is elevated above city streets.|
|Wauwatosa, Wisconsin, United States||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.