Have you ever been stuck blocks away from a busy intersection, then inched forward watching the light ahead turn green and red several times before you even reach the front of the line? This is frequently because a single traditional signal simply has too many jobs to do. As traffic grows, left turn arrows are added for safety. But these arrows add inefficiency, complexity, and pedestrian uncertainty. It all translates into fewer vehicles able to traverse the intersection. To compensate, planners and engineers have historically seen little choice but to resort to expensive and destructive solutions such as adding more lanes or even bridges.
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Fortunately there are a number of emerging designs that are finding innovative ways to serve left turns without traditional left-turn arrows at the main intersection. This restores maximum efficiency - and that can translate into huge increases in the number of vehicles served, and huge reductions in overall delay. So racing at 45 mph only to be stopped for several minutes at each signal can actually be much slower than traveling 25-35 mph through quality pedestrian environments - if you can get through the signal on the first try!

Many designs, originally conceived to simply move more vehicles, also have many amazing Place Making attributes that can support and even encourage quality pedestrian spaces and Transit Oriented Development. Some, such the Town Center Intersection actually require streets to be narrowed rather than widened in order to move more vehicles.read more...

Quadrant Intersections spread some of the traffic to "backage roads", which means prime right-of-way at the main intersection can be relinquished for landscaping, transit stations, and other amenities.

ThrU-Turn Intersections such as Bowties and Median U-Turns create a simpler, safer street for pedestrians to cross, and they often utilize roundabouts and center islands where place-making monuments and landscaping can help define a Place.

Continuous Flow Intersections are typically better suited for more auto-oriented environments, but they also achieve amazing efficiency and are good candidates for locations where eventual grade separation is a strong possibility.

In all, there are over a dozen specific design types that all have a common thread - they achieve high efficiency by handling left turns in creative ways. Some are relatively common in certain locales, others have yet to be built anywhere in the world! All are getting a lot more attention than they used to, and more and more are coming on-line quickly!

1. Very High Return on Investment!
2. Improves Quality of Life!
3. Many designs are very aesthetically pleasing, and can catalyze pedestrian-oriented "Places!"
4. Attracts investment to revitalize struggling areas!
5. More feasible to convert general purpose lanes into other uses such as transit only lanes!
6. Better access management, but also frequently better business access!
7. Reduces right-of-way impacts!
8. Avoids widening streets, and even grade separation!
9. Fewer conflicts and less congestion improves safety!
10. Better mobility enhances the local economy!