No left turn.
That is the simple concept behind the Superstreet traffic design which promises significantly faster travel times, plus a drastic reduction in auto-collisions and injuries.
These superstreets are ground level streets – not raised freeways or highways – that allow for greater volume of thru-traffic by re-routing traffic from side streets that would normally be trying to get across the main road. While the idea has been around in urban transport modeling textbooks for over 20 years, researchers from the North Carolina State University have been the first to test the concept in the real world and the results are promising.
The central concept to the superstreet design is a thoroughfare, a stream of constantly moving traffic that follows a main arterial road. Drivers wanting to cross the thoroughfare or to turn left are first required to make a right turn, joining the main stream of traffic. A little way down the superstreet they then make a U-turn after which they can continue on along the thoroughfare if they had been trying to turn left or they can turn right into the side street if this was their planned route. 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 study shows a 20 percent overall reduction in travel time compared to similar intersections that use conventional traffic designs,” Dr Joe Hummer, professor of civil, construction and environmental engineering at NC State and one of the researchers who conducted the study said. “We also found that superstreet intersections experience an average of 46 percent fewer reported automobile collisions – and 63 percent fewer collisions that result in personal injury.”
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