As state and local dignitaries officially dedicated the state’s first “diverging diamond” interchange Friday on Ashford Dunwoody Road at I-285 in Dunwoody, figures showed accidents at the interchange are down over the same period last year.
The three-year, $5.5 million project opened to traffic in June and sits amid metro Atlanta’s busiest business centers. Close to 55,000 vehicles a day pass through the interchange.
The new design channels north- and southbound traffic on Ashford Dunwoody Road into the left lanes of the overpass to allow unencumbered left turns onto I-285. Traffic is then diverted back to the right lanes as it leaves the overpass.
“I think it works well,” said Dunwoody resident Anne Glenn, who uses the interchange regularly. “It allows traffic to move on Ashford Dunwoody without all the delays I used to see.”
Fewer accidents are another benefit. Figures from the Dunwoody Police Department show accidents at Ashford Dunwoody Road at I-285 are down almost 30 percent since the new configuration was launched. Records show 28 accidents reported at the interchange from June 1 through Nov. 14 last year, while 20 accidents were reported at the site during the same period this year.
Friday’s ceremony marked completion of signaled crosswalks and a protected sidewalk that runs between the four traffic lanes on the overpass.
The DDI project was launched in 2009 by the Perimeter Community Improvement Districts to improve the more-than-40-year-old interchange. The PCIDs received grant funding from the State Road and Tollway Authority and DeKalb County for engineering and design work. The Georgia DOT funded the $4.6 million cost of construction.
Traffic flow figures will not be completed until summer, but most of the feedback has been positive, said Todd Long, Georgia DOT deputy commissioner. The DOT is working on two other diverging diamond interchanges in Gwinnett County.
“It’s been hugely successful at moving traffic,” said Brandon Beach, a member of the Georgia DOT board of directors. “Some people were a little nervous about it at first, but now that they’ve driven it, they like it.”
However, kinks are still being worked out at Ashford Dunwoody and Hammond Drive. Here, traffic exiting westbound I-285 often has to cut across multiple lanes of northbound traffic on Ashford Dunwoody to access Perimeter Mall at Hammond. At this site, accidents are up from 14 from June 1 through mid-November last year to 16 during the same period this year.
“We’re still working with the timing, seeing if we can get that ‘weave’ fixed,” said David Purcell, chief financial officer for the PCIDs.
PCID leaders say the design succeeds in providing a cheap fix to an interchange long overdue for an upgrade.
“Overall, I think the diverging diamond is money well spent on an improvement,” Purcell said.
About the Author
