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.[1] 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.

Three-level diamond diagram. Arrows are for traffic driving on the right.

Road enthusiasts sometimes use the terms volleyball interchange or split-level diamond interchange to refer to these interchanges.[2]

Description

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).

Examples
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 51°16′16.9″N 6°45′1.8″E; 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.

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References
  1. Indiana Department of Transportation, "Interchanges" (PDF). (203 KiB), pages 21 and 22
  2. Oglesby, Scott. "Volleyball Interchange". Kurumi's Field Guide to Interchanges. Retrieved 23 August 2013.
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