Quadrant roadway intersection
A quadrant roadway intersection adds an additional "quadrant roadway" between two legs of an intersection. This roadway adds two three-way intersections in addition to the original four-way intersection moving all left turns (in right-hand traffic countries) or right turns (in left-hand traffic countries) from the main intersection. The design is intended to improve traffic flow by reducing signal timing phases from four to two in the main intersection. The design is intended for intersections where large artery routes meet in an area of dense development and high pedestrian volume.
Proponents also point to a reduction in places where accidents could occur from vehicles potentially crossing paths as well as a low development cost compared to roundabouts or the more complex single-point urban interchange designs. Opponents point to the increase in points where accidents could occur with merging traffic as well as the non-traditional nature of the design which has the potential to confuse drivers. Opponents also refute low cost claims pointing to right-of-way and construction costs of the quadrant road.
Single-quadrant intersections (pictured above) feature a single quadrant road.
Another variant links grade-separated roads, generally a faster road with denser traffic, to a less traveled, slower road, via the quadrant road. This design is referred to as a one-quadrant interchange or as a single-loop intersection. This type of junction is common in Germany, where it is called a "partial at-grade intersection" (German: Teilplangleicher Verkehrsknoten). A so-called two-quadrant interchange also exists, which adds a second quadrant road (although the term "two-quadrant interchange" could be applied to any grade-separated junction in which there are ramps in two quadrants).
-  Dundas Street and Cawthra Road, Mississauga, Ontario
-  Highway 7, Langstaff Road, and Dufferin Street, Vaughan, Ontario
-  Highway 7 and Bathurst Street, also in Vaughan, Ontario
-  Highway 7 and Yonge Street, Markham, Ontario
-  Highway 7 and Bayview Street, Markham, Ontario
-  Bloor Street and Stevenson Road, Oshawa, Ontario
- Wallingford, Connecticut – Colony Road and Church Street
-  Gurnee, Illinois – Illinois Route 21 and Illinois Route 132
-  Carmel, Indiana – Meridian Street and 146th Street via Greyhound Pass
- Carson Township, Pottawattamie County, Iowa – Iowa Highway 92 and US 59. Two-quadrant interchange (at ).
-  Owings Mills, Maryland – Maryland Route 140 and Owings Mills Boulevard
- Ann Arbor, Michigan – Washtenaw Avenue and Huron Parkway. Platt Road is the quadrant road.
- Birmingham, Michigan – Woodward Avenue and Maple Road. Peadbody Street is used as the quadrant road.
- Lansing, Michigan – Martin Luther King Avenue at Grand River Avenue
- Billings, Montana – Hilltop Road and Lake Elmo Drive
- Clarks, Nebraska - US 30 at Nebraska Highway 92. Link 61D is the connector road.
- Golden Triangle, New Jersey – Kaighns Avenue and Chapel Avenue
-  Depew, New York – New York Route 130 (Broadway Street) and New York Route 277 (Union Road)
- North Carolina and Virginia - Blue Ridge Parkway features numerous grade-separated one- and two-quadrant interchanges along its length.
- Cary, North Carolina – High House Road and Cary Parkway (proposed)
-  Akron, Ohio – Exchange Street and Wolf Ledges Parkway. (The quadrant roadway has its own name, Arc Drive, but has no driveways or addresses and serves solely as the quadrant roadway.)
- Fairfield, Ohio – State Route 4 at State Route 4 Bypass (4B) and Ross Road. Diversion Road is used as the quadrant road.
- Knox County, Tennessee – State Route 33 (Maryville Pike) and State Route 168 (Governor John Sevier Highway). Two-quadrant interchange.
- Smyrna, Tennessee – Lee Victory Parkway (State Route 102) and Old Nashville Highway. One-quadrant interchange.
- Aldie, Virginia – John Mosby Highway (US Route 50) and James Monroe Highway (US Route 15)
- Mill Creek, Washington – Washington State Route 527 and Washington State Route 96 via 16th Avenue SE (partial).
- Turner-Fairbank Highway Research Center (August 2004). "Signalized Intersections: Informational Guide". ALTERNATIVE INTERSECTION TREATMENTS. United States Department of Transportation. Retrieved 3 January 2010.
- Cooke, Jordan (Mar 24, 2009). "Left turns left out of road redesign". Cary News. Archived from the original on April 10, 2009. Retrieved 3 January 2010.
- Hummer, Joseph E. (May 14, 2003). "Moving More Cars Through the Same Space Using Unconventional Intersection Designs" (PDF). NCDOT Traffic Engineering Conference. North Carolina State University. Retrieved 3 January 2010.
- "Quadrant Roadway Intersection vs. Traditional Intersection" (PDF). Community Planning Assn. of Southwest Idaho. Retrieved 3 January 2010.
- "Quadrant Roadway Intersection". Alternative Intersections/Interchanges: Informational Report (AIIR). Federal Highway Administration. April 2010. FHWA-HRT-09-060. Retrieved September 4, 2017.
- Wilbur Smith Associates; Thompson Transportation; HDR; Hummer, Joseph E., Ph.D., P.E. (April 21, 2008). "Intersection Concept Layout Report" (PDF). High Volume Intersection Study (PDF). Community Planning Association of Southwest Idaho. Retrieved September 4, 2017.
- Nelson, Catherine M., P.E.; Belleque, Kent; Crossler-Laird, Rich; Gutierrez, Rodger; Henson, Christopher; Lindland, Steve; Nguyen, Lily; Polly, Dave; Warrick, Dave (2012). "Chapter 2: Design Controls and Criteria" (PDF). ODOT Highway Design Manual (PDF). Oregon Department of Transportation. Retrieved September 4, 2017.
- "Archived copy" (PDF). Archived from the original (PDF) on April 12, 2015. Retrieved December 23, 2014.CS1 maint: Archived copy as title (link)
- Institut für Straßen- und Eisenbahnwesen am KIT: Entwurf und Bau von Straßen – Teil: Straßenentwurf. (PDF; 8,44 MB) Abgerufen am 7. September 2013.
- Maze, T.H.; Hochstein, Joshua L.; Souleyrette, Reginald R.; Preston, Howard; Storm, Richard (2010). Appendix A, Detailed Green Book Review with Comments (PDF). National Cooperative Highway Research Program (NCHRP) Report 650: Median Intersection Design for Rural High-Speed Divided Highways (PDF). Transportation Research Board. doi:10.17226/22958. ISBN 978-0-309-43543-7. Project Number 15-30. Retrieved September 12, 2017.
- "Cary Parkway and High House Road Intersection". Town of Cary, North Carolina. Retrieved 3 January 2010.