Just about every time we drive, we’re forced to make left turns, risking head-on or 90-degree collisions with cars coming from the opposite direction. An innovative new highway interchange significantly reduces this risk. Called a diverging diamond, this design allows drivers to avoid the hazardous turns altogether.
Diverging diamond interchanges may appear complicated at first glance, but research reveals that drivers consistently navigate them with few issues. Roads cross each other so drivers on the right hand side of the road cross to the left and vice versa. Therefore, drivers on a diverging diamond interchange don’t have to turn against traffic when they go left; they simply merge away to the left. The roads cross again further down the street after left turns for both sides. Drivers entering the interchange simply merge left or right, and only have to worry about oncoming traffic from one direction instead of two.
France constructed some diverging diamond highways in the 1970’s, but they didn’t really catch on in America until a graduate student named Gilbert Chlewicki wrote about the design in 2000 and realized his idea had already been implemented overseas. Nearly a decade later, diverging diamonds began to gain popularity as states such as Missouri and Utah adopted the concept. Wired reports that since 2009, 22 states have built 62 of these innovative, safe roads.
Research shows they work. University of Missouri engineers, along with colleagues around America, performed “the first in-depth safety analyses” in 2015. These are the stats: five out of seven intersections experienced “serious safety improvements.” Deadly crashes occurring on terminal ramps declined by more than 60 percent. And crashes that do occur don’t result in death as often. The team estimated that crashes overall on the new safe roads are reduced by 33 percent.
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