Good news for the Portland Bureau of Transportation: One of their newest tools to improve crossing safety at intersections just got a stamp of approval from new research from the nonprofit Insurance Institute for Highway Safety (IIHS).
Last summer PBOT rolled out a new type of speed bump they call ‘left turn calming’. These rubberized bumps are placed in intersections where car users tend to turn left too quickly and/or cut the corner. The idea is that the bumps force people to make sharper turns, drive at slower speeds, and have better visibility of people in the crosswalk.
According to new research from Washington D.C., this “centerline hardening” treatment is associated with a 70.5% decrease in conflicts between drivers and crosswalk users. A paper published this month by IIHS-funded researchers Wen Hu and Jessica Cicchino, also found that the bumps lowered mean left-turn speeds by nearly 10% and reduced the odds of people going over 15 mph while turning left by 67%. Hu and Cicchino studied 10 intersections in D.C.
Left turn collisions are the bane of traffic safety advocates. In 2018 they accounted for almost one third of all intersection collisions nationwide that involved a person on foot. According to State of Oregon data, 20% of crashes involving walkers (between 2006 and 2015) were the result of left-turning drivers failing to yield to people in crosswalks at signalized intersections.
Last year PBOT installed left turn calming bumps at over two dozen intersections citywide. Learn more on their website.
— Jonathan Maus: (503) 706-8804, @jonathan_maus on Twitter and firstname.lastname@example.org
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