Rampant sprawl in Orange County, Florida, was creating rush hour back-ups half a mile long at the Town of Windermere’s quaint Main Street. The conventional solution—widening Main Street to four-lanes—would have destroyed the town’s character. Planner Brian Canin and transportation designer Jurgen Duncan instead proposed a pair of single-lane modern roundabouts with circulating speeds of 12-14 miles per hour. The Town approved construction and, to everyone’s amazement, the traffic congestion disappeared. In the low-speed environment, motorists stop for pedestrians and wave them across the street. Canin and Duncan saved Main Street.
Unlike the big, fast, scary and dangerous rotaries and traffic circles of old, compact modern roundabouts—when properly designed—reduce entry, circulating, and exit speeds to below 20 miles per hour.[i] Because kinetic energy increases as the square of velocity,[ii] a vehicle traveling 45 miles per hour through a conventional intersection has nine times the kinetic energy of one traveling 15 miles per hour through a modern roundabout.[iii] Reducing kinetic energy lessens crash severity. Intersections converted to single lane roundabouts experience a 76 percent reduction in injuries and a more than 90 percent reduction in fatalities.[iv] Roundabouts replace the “kill zone,” where deadly head-on and T-bone collisions occur, with a central island that can be beautiful.