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Florida Traffic Engineers Propose “Diverging Diamond” to Slash Intersection Crashes

Authorities in Delray Beach are investigating an intersection crash at Federal Highway and Northeast First Street, where a fitness club mogul in a Lamborghini t-boned an 82-year-old Uber driver in a Buick. Investigators believe speed and alcohol were factors in the crash, according to the Orlando Sentinel.crosswalk1

But what if those two vehicles never needed to cross paths? This is the theory behind the traffic re-engineering proposed by Florida Department of Transportation. Although we typically think of “advancements” in travel these days as being technological or electronic, this has to do with good old-fashioned road design. It’s called the, “diverging diamond interchange,” or DDI.

The goal of this design is to not only reduce the amount of potentially hazardous left turns, but also to make it tougher to enter a highway on-ramp traveling the wrong direction.

It’s actually not the first time the interchange has been used. In fact, according to Wired, since 2009, there have been 62 DDI built in 22 states, and there are many more under construction. It was first created in France during the 1970s, but a U.S. graduate student who wrote a paper on it back in 2000 sparked its growing popularity here in the U.S. (That student is now a director at the ATS/American design firm.) The very first of these interchanges was constructed in Springfield, Missouri. At that location, traffic collisions have fallen by 60 percent.

The strength of the design is the fact that it has a “zero tolerance policy” when it comes to left turns. These turns are dangerous because they force drivers to be at risk for especially violent 90-degree collisions and head-on car accidents. In addition, traffic analysts say, they’re not very efficient. That’s because particularly at busy intersections, the through-traffic is slowed by the left turn arrows. The green light time is being wasted by allowing safer left turns.

The DDI is best for areas where surface roads cross with highways and where cars are moving between those two.

The first in-depth analysis of the DDI was done last year in a paper published by The Transportation Research Board. Of the seven intersections scientists examined, five of those resulted in major improvements in safety. The conclusion was that the DDI design could potentially reduce the number of crashes by fully a third. What’s more, even those crashes that did occur tended to be less serious. Deadly crashes on terminal ramps dipped by 60 percent. Property damage dropped by 50 percent.

While at first glance it might seem that drivers could be easily confused by these configurations, traffic researchers say drivers very rarely went the wrong way with DDI designs. They found that even when drivers did err, which was usually after dark, the crashes that resulted were usually not fatal.

What’s especially interesting about this idea is how fast it’s catching on. The U.S. has been notoriously slow to adapt its traffic patterns, even when it becomes clear they aren’t working. But more and more Florida communities are adopting this design.

The one downside of DDI is that it’s primarily only for highway interchanges, which means it’s probably not going to be much help in most urban intersections. Nonetheless, anything that can improve driver safety and lower traffic deaths is worth exploring.

Call Freeman Injury Law — 1-800-561-7777 for a free appointment to discuss your rights. Now serving Orlando, West Palm Beach, Port St. Lucie and Fort Lauderdale.

Additional Resources:

New “Diverging Diamond” Intersection Design Cuts Crashes by Sixty Percent, June 5, 2016, By David Z. Morris, Fortune

More Blog Entries:

Teens at Higher Risk of Injury, Death in Florida Car Accidents, Sept. 16, 2016, Orlando Car Accident Lawyer Blog

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