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Roundabouts Reduce Traffic Congestion, Increase Pedestrian Safety

July 26, 2007

In recent studies conducted by the National League of Cities, one of the main concerns facing local governments was growing congestion. Many of these problems were associated with signalized interchanges.

Enter concrete pavement roundabouts. In congested areas, they have been proven to not only reduce congestion but also provide enhanced safety. And, concrete has the durability to take the constant vehicle-turning movements. Formally known as traffic-calming devices, concrete roundabouts enable the movement of heavy traffic volumes during peak operating hours.

Concrete pavement roundabouts provide safety and aesthetic benefits to interchanges while easing congestion.

When properly designed, they can ease traffic congestion by keeping traffic moving at a deliberate and steady pace. A single lane roundabout can accommodate more than 2,000 vehicles per hour from all entry legs. Two- and three-lane roundabouts can handle traffic volumes of 4,000 and 8,000 vehicles per hour, respectively.

Traffic calming is one area that all city officials agree needs to be addressed, especially in areas that must accommodate heavy vehicle traffic, as well as pedestrians and bicycles. Moreover, the intersection of Benedict and Cleveland is in need of being rebuilt as a roundabout, for many reasons. Ask anyone who uses the intersection or has seen it used just how dangerous it can be. Why wait for a major accident or a fatality to fix this obvious and long-standing problem? Ask for the state’s help, and Rebuild the Benedict/Cleveland circle!

Safer Than Signals

Roundabouts typically do not rely on traffic lights or stop signs to maintain traffic flow. Fewer abrupt stops and starts and a more continuous flow of traffic mean that motorists get where they need to go more quickly, with less frustration, and safer, too.

One of the main benefits of concrete roundabouts is their ability to reduce traffic accidents, especially the fatal accidents caused by high speed side impact crashes. Also, because of the versatility of concrete, crosswalks and aesthetic features can be added in a range of colors using decorative concrete techniques.

Decorative concrete can impart both safety and aethetic features to roundabouts, crosswalks, and more.

Another benefit of concrete in roundabout applications is that it resists shoving and rutting, which is a common occurrence on asphalt pavements. In particular, shoving typically occurs at intersections and in other areas, particularly where trucks, buses, or heavy traffic causes the asphalt to shove over, triggering a number of problems, including severe vehicle damage.

American Concrete Pavement Association (APCA) Offers Pavement Thickness Design Tips

The two primary design aspects for roundabouts are pavement thickness and jointing. For roundabouts and traditional intersection pavements, typical concrete thicknesses can range from 5 to 10 inches (125 to 250 mm).

The exact required thickness will depend on expected traffic, local conditions, past history, and other factors. Additionally, designing and laying out the single and multiple lane roundabouts using rideable raised medians and islands will allow large trucks to easily navigate the interchange.

ACPA is nearing completion on a new publication with updated construction and design practices for concrete pavement roundabouts. For more information, contact Scott Haislip at 219-922-8104 or visit the APCAwebsite.

— Matthew Phair

Editor’s note: Matthew Phair is a Croton-on-Hudson, New York-based writer and editor. He has authored literally hundreds of articles about the application, marketing and impact of technology in construction.

On July 27, 2007 11:17 PM, Leo Wiegman said:

Matt: Thanks for this excellent article about roundabouts. This kind of traffic-calming, traffic-flowing idea may be just the ticket for Croton, not only for the Benedict-Cleveland circle, but perhaps for other intersections that jam traffic and create pedestrian-to-auto conflicts. Dare I say the Croton-Harmon station entrance on Croton Point Avenue? That intersection sees 2000+ vehicles at rush hour twice a day. Leo Wiegman


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