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Diverging-diamond improves Pleasant Hill traffic

Cars travel through the diverging-diamond interchange on Pleasant Hill Road at Interstate 85. Officials say the new design has drastically improved traffic in the Gwinnett Place area. (Staff Photo: Camie Young)

Cars travel through the diverging-diamond interchange on Pleasant Hill Road at Interstate 85. Officials say the new design has drastically improved traffic in the Gwinnett Place area. (Staff Photo: Camie Young)

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Cars travel through the diverging-diamond interchange on Pleasant Hill Road at Interstate 85. Officials say the new design has drastically improved traffic in the Gwinnett Place area. (Staff Photo: Camie Young)

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Joe Allen of the Gwinnett Place Community Improvement District walks in the pedestrian lane of the diverging-diamond design at Pleasant Hill Road at Interstate 85.

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Cars travel through the diverging-diamond interchange on Pleasant Hill Road at Interstate 85. Officials say the new design has drastically improved traffic in the Gwinnett Place area.

Just months after the 2013 opening of Gwinnett’s first diverging diamond interchange, officials are preparing for the second.

In a few months, crews will convert the Jimmy Carter Boulevard bridge over Interstate 85 to the new design, which has brought a smoother traffic flow to Pleasant Hill Road.

“The feedback we are getting from the business community is very positive,” said Joe Allen, director of the Gwinnett Place Community Improvement District, where the Pleasant Hill bridge is located. “Everyone I have spoken with agrees that the DDI looks great and is moving traffic more efficiently.”

Coupled with some work to coordinate traffic signal timing in the area, Allen said people saw a marked improvement in traffic thanks to the new design, which sends drivers to the opposite side of the road to allow free-flowing turns.

In one study, results showed a 51 percent decrease in the average number of stops and a 43 percent decrease in total delay along Pleasant Hill. A September study about CID-wide timing project encompassing 49 signals showed a reduction of 18 percent in stops and 23 percent for total delay. Analysts said that translated to a $3.9 million per year savings in time and fuel for local drivers.

Allen said CID officials plan a more in-depth study during the new year.

“When traveling through the interchange it now only takes one signal cycle for me to travel through the interchange where before the DDI was constructed, it could take two or more,” Allen said. “Through field observations it appears that more vehicles are using the interchange and certainly through comments that have been received the public seems to have noticed an improvement in mobility through the interchange.”

Work on the Jimmy Carter bridge has been delayed, Warbington said, mostly due to rain and some construction issues.

But the delay has allowed officials to coincide the work with a planned Georgia Department of Transportation project to extend a lane on the ramp of I-85 northbound, allowing a longer merger onto the interstate.

Warbington said that should allay concerns that traffic would continue to stack up onto Jimmy Carter from the Peachtree Corners side of the bridge.

“It’s going to make for a better opening of the two,” Warbington said of the expected transition to diverging-diamond, which will occur on a weekend in the spring. “It’s going to make our DDI perform better than what we expected.”

As many of the Gwinnett Village property owners also own property near the Pleasant Hill bridge, Warbington said the opening of the county’s first diverging-diamond has created a lot of excitement for the second.

“We have heard nothing but positive things,” about the new design, he said. “We are very excited to see what happens with ours.”