Reader's Digest October 2009 - Quick Study: Unlocking Gridlock
•This feature, light on text but heavy on numbers, sources and graphics, provides a snapshot of our driving habits along with fun facts. Reader's Digest Unlocking Gridlock - (PDF)
Circles vs. Signals - Are modern traffic circles better than traditional signalized intersections? If so, how
are they better?
• Studies from the Insurance Institute for Highway Safety (www.iihs.org) found that there were 76% fewer injury-producing crashes -- and 39% fewer crashes overall -- at modern traffic circles than there were at intersections with signals or stop signs. Such circles (also called "rotaries" or "roundabouts" and common in Europe) reduce traffic speed and eliminate the right-angle turns that often lead to accidents. source: Parade Magazine 07/09/00
Go to the Insurance Institute for Highway Safety for more information
Driving a Roundabout - How do I approach and drive the roundabout?
• Remember drivers entering the roundabout must yield to pedestrians using crosswalks and to vehicles already traveling in the roundabout lanes.
• A modern roundabout is a circle designed for very low traffic speeds, about 15 mph. Entrances and exits are curved so that motorists must travel slowly — far different from the rotaries of decades ago, which typically allowed drivers to enter at 35 mph or faster. The modern roundabout typically needs to be about 100 feet across so that it can be properly designed to slow the entering traffic. Reduced speeds help explain roundabouts’ safety, other factors in their success are the elimination of left turns against oncoming traffic, the elimination of right-angle collisions, and a reduction in rear-end collisions. Raised “splitter” islands divide the roadway at the entrances and exits, providing refuge for pedestrians and at the same time separating opposing traffic. Roundabouts may help reduce traffic delays, vehicle emissions, fuel consumption, and noise. They can save local governments money by avoiding the need to buy, install, and maintain traffic signals. After a long period of being out of favor among traffic engineers, roundabouts have been built in growing numbers in recent years. “We use roundabouts often in both infill and greenfield design,” says Peter Swift of Swift and Associates, town planners and civil engineers in Longmont, Colorado. Roundabouts, Swift says, can accommodate high road capacity, give retail and commercial enterprises valuable exposure to traffic, provide pedestrian comfort, and create “a very safe multi-modal environment,” all at the same time. Swift points out a two-lane roundabout in a commercial, mixed-use location in Towson, Maryland, that handles 30,000 to 40,000 vehicles a day safely.
• Driving Modern Roundabouts - video on roundabout safety for cars, pedestrians and bikers.
• Federal Highway Administration - reference materials on roundabouts
• Institute for Transportation Engineers - traffic calming
• IIHS Safety and Capacity Study - (PDF)
• ITE Performance Study - (PDF)
• ITE UAE Study -a study of three cities - (PDF)
