The left turn is perhaps the most dangerous of legal driving maneuvers, simply due to its nature: you're turning -- often from a standstill -- across another lane of traffic that's moving in the opposite direction.
Here's how it works: instead of a quick left at the intersection of a surface road (as opposed to a freeway), the superstreet re-routes left-hand turns and cross-traffic by forcing the driver to make a right turn, then make a U-turn around a broad median.
While this may seem time-consuming, the study shows that it actually results in a significant time savings since drivers are not stuck waiting to make left-hand turns or for traffic from cross-streets to go across the thoroughfare.
The design promises a 20 percent overall reduction in travel time and a 46 percent reduction in collisions. It's the result of the largest-ever study of superstreets and their impacts, and includes assessments of three existing superstreets with traffic signals located in eastern and central North Carolina, and 13 more across the state without signals.
The superstreet concept isn't new; it's been around for more than two decades. But the researchers say little has been done to examine it in real-world conditions.
(The only problem I see? This appears to be a pedestrian's nightmare. But perhaps it's more effective in less-dense locales.)
The researchers will present their findings on Jan. 24 at the Transportation Research Board Annual Meeting in Washington, D.C.