Construction continues on the upcoming roundabout at the intersection of Fairground Street and Allgood Road in Marietta. Chicopee Drive, right, will be closed from July 2 to August 3.
Staff/Laura Moon
Staff/Laura Moon
The roundabout is part of a $5 million SPLOST-funded project that includes medians, new sidewalks with brick accents, and street lighting on Fairground Street between Allgood Road and Rigby Street.
Westbound drivers on Allgood Road, coming away from the QuikTrip gas station, will still be able to turn left onto North Fairground Street. Only the portion of Allgood that turns into Chicopee Drive, just west of North Fairground Street, will be closed, city engineer Jim Wilgus said.
The roundabout should be open before school begins in early August, Wilgus said.
About 1,200 vehicles use the intersection during peak hours, with about 14,220 vehicles traveling through the intersection a day, according to the city.
The roundabout is part of a $5 million SPLOST-funded project that includes medians, new sidewalks with brick accents, and street lighting on Fairground Street between Allgood Road and Rigby Street. It will cost $450,000 to build, plus another $193,911 in right-of-way expenses, Wilgus said.
The idea for the roundabout came from the engineering consultant for the project, Croy Engineering, which told the city that the grading and intersection geometry at the site were favorable for a traffic circle.
Drivers enter a roundabout and travel in a one-way, counter-clockwise direction until they reach their desired roadway. Drivers entering the roundabout must yield to other drivers already in the traffic circle. There are no stop signs, only yield signs.
Voters approved funding another roundabout, at the intersection of Mountain View Road and Polk Street, for $490,000 in the SPLOST 2011 referendum. Wilgus said that project is about two years from getting under way.
Cobb County built its first roundabout at West Sandtown and Villa Rica roads in 2008. It has two more under construction, one at Davis Road at Holly Springs, which should be mostly complete by early next month, and another on Lower Roswell Road at Timber Ridge Drive, which should get under way later this summer, county spokesman Robert Quigley said.
Replacing an existing intersection with a roundabout reduces accidents by more than 35 percent and injuries by more than 60 percent, according to the Georgia Department of Transportation.
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Slow and go also means less delay than a stop light, especially the other 20 hours a day people aren’t driving to or from work. Average daily delay at a signal is around 12 seconds per car. At a modern roundabout average delay is less than five seconds. Signals take an hour of demand and restrict it to a half hour, at best only half the traffic gets to go at any one time. At a modern roundabout four drivers entering from four directions can all enter at the same time. Don’t try that with a signalized intersection.
Here’s a quote:
“By 2025, a quarter of all drivers in the United States will be over the age of 65. Intersections are the single most dangerous traffic environment for drivers of any age with left-hand turns being the single most dangerous traffic maneuver that any of us can make. Forty percent of all crashes that involve drivers over the age of 65 occur at intersections. This is nearly twice the rate of experienced younger drivers. AARP would like to see more roundabouts constructed because of the many safety benefits that they present for drivers of all ages.” - Jana Lynott, AARP Public Policy Institute
But let's change timing of lights so we don't delay traffic as we have in the past...