Summary of "Placemaking Alternative Intersection" research underway for the North Carolina Department of Transportation.
What is a Quadrant Intersection?
Instead of managing lefts directly at the main intersection, a Quadrant redirects those movements along a back-way path as shown here. Notice that vehicles on the red path have no out-of-direction travel. Those following the blue path have some out-of-direction, but even they are likely to get to where they’re going quicker due to less congestion. Former left-turn lanes can now be converted into planted medians with trees and pedestrian refuge areas in the middle of cross-walks. The Quadrant backway improves access and visibility for parcels along that backway, adding value to that land and making it attractive for mixed-use development. There are many variations of this idea, such as a four-quadrant system that converts blue paths into red paths, but this diagram is a good start.
Concepts in Greenville: Quadrants at Arlington and Evans
The series of sliders below show Before / After for the four Quadrant intersection at Arlington Blvd and Evans Street.