Summary of "Placemaking Alternative Intersection" research 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:
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Red path has no out-of-direction travel.
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Blue path has some out-of-direction, but still faster due to less congestion.
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Former left-turn lanes converted into planted medians
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Pedestrian refuge areas in the middle of cross-walks.
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Improves access and visibility for backway parcels, for a larger Activity Center.
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.
Before: Stroad with pathways for lefts, forming a "Kitty-Corner Quadrant"
After: Sets stage for buildings to transition from auto-oriented to walkable.
Notice that right-of-way and intersection shrinks, even though the system can handle more vehicles!
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Left: Shortly after project opens.
Right: Years later after market has time to react to walkable environment! Many original buildings still there, but many "higher and better" mixed-use buildings have also been built.
Before: Auto-oriented commercial, but with pathway for diverting lefts.
After: Community amphitheater, parking garage, residential + commercial.
Cars drive slower, but travel faster due to less signal delay. System can handle more vehicles, which is good because more development means more vehicles, even with many trips via Alt. Modes.
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.