Left turns are terrible. When they aren’t extremely hazardous for drivers, they cause significant delays for other movements in the intersection because of dedicated left turn phases. Engineers have been plagued with this problem for years and have come up with many solutions, but usually the public doesn’t want anything to do with them. Even when they work exceptionally well, the Jughandle, the Michigan Left, and the all-powerful SPUI (single point urban interchange) all took time to introduce to the public. Even the roundabout is feared in areas where drivers don’t use them often, and the super-street causes uproar over driveway access to businesses. A personal favorite of mine, one I studied extensively in an unconventional intersection design course, is the Diverging Diamond Interchange. I designed a hypothetical DDI for Raleigh back in undergrad. It’s neat, but it’s been a hard press on the public to try something as different as driving on the wrong side of the road. Continue reading →
Mike Roselli is a Civil Engineer and consultant, licensed in the States of NC, SC, GA, and FL, and is focused on providing land development services to clients building in the Triangle Area. He currently resides in Cary, NC.