Quadrant roadway intersection

A single quadrant roadway intersection.

A quadrant roadway intersection adds an additional "quadrant roadway" between two legs of the 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.[1][2]

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.[1][3][4] 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.[1][3]

Variants

Single quadrant intersections (pictured above) feature a single quadrant road. Double quadrant intersections add an additional quadrant road placed opposite of the other quadrant road. Another variant links grade-separated roads via the quadrant road, typically to bring together a faster road with denser traffic with an overpass (or flyover) over a less traveled, slower road. This design is also referred to as a single-loop intersection.[4]

A One Quadrant Interchange uses an overpass and two T-intersections.[5] This is the only and very common one quadrant variant in Germany, where it is called a "Partial At-grade Intersection" (German: Teilplangleicher Verkehrsknoten).[6]

Examples

Canada

The single-loop variant is used frequently in the Thornhill area, in the Greater Toronto Area in Ontario, Canada, examples include:

United States

Germany

References

  1. 1 2 3 Turner-Fairbank Highway Research Center (August 2004). "Signalized Intersections: Informational Guide". ALTERNATIVE INTERSECTION TREATMENTS. United States Department of Transportation. Retrieved 3 January 2010.
  2. ↑ 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.
  3. 1 2 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.
  4. 1 2 "Quadrant Roadway Intersection vs. Traditional Intersection" (PDF). Community Planning Assn. of Southwest Idaho. Retrieved 3 January 2010.
  5. ↑ "Archived copy" (PDF). Archived from the original (PDF) on April 12, 2015. Retrieved December 23, 2014.
  6. ↑ Institut für Straßen- und Eisenbahnwesen am KIT: Entwurf und Bau von Straßen – Teil: Straßenentwurf. (PDF; 8,44 MB) Abgerufen am 7. September 2013.
  7. ↑ "Cary Parkway and High House Road Intersection". Town of Cary, North Carolina. Retrieved 3 January 2010.
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