Quadrant roadway intersection

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Sketch of a Quadrant Roadway Intersection
Sketch of a Quadrant Roadway Intersection

A quadrant roadway intersection includes an extra roadway between two legs of the intersection. This roadway adds two three-way intersections in addition to the original four-way intersection.

The advantage is that all left-turns1 are removed from the primary intersection. Therefore, the three-way intersections may operate with three signal phases and the four-way intersection may operate with only two signal phases. The reduced quantity of signal phases improves the efficiency of the intersection.

The disadvantage, however, is that motorists wishing to turn left from either the major or minor road may have to travel further to do so. Also, right-of-way and cost limitations may reduce the feasibility of this type of intersection treatment.

1 For countries that drive on the right-hand side of the road.

[edit] Grade separations

In some areas, the two main roads are grade-separated (with one traveling over the other), and the quadrant road serves to link the two main roads together. This is most frequently found in the Greater Toronto Area in Ontario, Canada.

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