All drivers know that intersections pose particular dangers to motorists, passengers, pedestrians and cyclists. In fact, the Federal Highway Administration (FHWA) reports about 2.5 million intersection accidents every year — most involving left turns — and 40% of all crashes happen at intersections. This represents the second largest category of accidents, behind only rear-end collisions. Intersections are also the location of 50% of serious collisions and 20% of fatal collisions.¹
So why exactly are intersections so dangerous? A variety of factors create challenging conditions at intersections. Typically, intersections represent a large amount of traffic converging in one area. In a standard two-lane intersection, there are 32 conflict points that could potentially lead to traffic accidents.² Drivers are required to either slow down or come to a complete stop. Drivers also need to interpret sometimes-complex traffic signals.
Because of the danger of intersections, the FHWA has started recommending that agencies consider implementing roundabouts instead of standard intersections during new construction or reconstruction projects. Roundabouts have proven to be a much safer, more efficient way to manage speeds while moving traffic through an intersection.
This is because roundabouts reduce the number of conflict points at an intersection from 32 to eight — a 75% reduction. Additionally, the conflict points occur while all traffic is traveling in the same direction. This substantially reduces the severity of accidents by eliminating the likelihood of sideswipe or head-on collisions. Studies have shown that converting a standard two-way stop-controlled intersection into a roundabout can reduce severe crashes by 82%, while converting a signalized intersection into a roundabout can reduce severe crashes by 78%.³
For your roundabout to effectively improve traffic flow, manage traffic speeds and reduce accidents, it’s important to install signs and pavement markings that deliver clear and consistent communication.
One of the main challenges of planning effective roundabouts is the wide entrance angle of a standard roundabout, which makes it more difficult to accurately and consistently predict the location of a vehicle relative to the traffic sign. This, in turn, makes it challenging to ensure that light will be reflected from the sign to the driver. Without reflected light, the driver may not be able to see the road sign at night, dawn and dusk. To counteract this challenge, it’s important to use sign sheeting that creates a large, bright cone of reflectivity. This helps to ensure that light is reflected back to the driver so the sign can be seen despite a possibly disadvantaged sign location.
Here are some other things to keep in mind when you’re choosing signs and pavement markings for roundabouts:
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¹ Source: Statistics on Intersection Accidents. Retrieved from https://www.autoaccident.com/statistics-on-intersection-accidents.html
² Source: Roundabouts and Mini Roundabouts. (2019). U.S. Department of Transportation. Retrieved from https://safety.fhwa.dot.gov/intersection/innovative/roundabouts/
³ Source: Proven Safety Countermeasures: Roundabouts (2017). U.S. Department of Transportation. Retrieved from https://safety.fhwa.dot.gov/provencountermeasures/roundabouts/
⁴ Source: Evaluation of Fluorescent Orange Signs, Texas Transportation Institute, TDOT, TX-00/2962-S, 2000