The 2013 study focused on the number of crashes along four stretches of road where operational and safety issues were addressed using funding from the 2005 special purpose local option sales tax, said David Montanye, manager of the DOT’s traffic operations division.
Chairman Tim Lee said he and the other commissioners were “very pleased” with the safety report.
“I think we have to remember, with any of our SPLOST projects, the primary responsibility is always to improve safety of the motoring public and the walking public,” Lee said. “You cannot improve effectiveness or efficiency at the expense of safety.”
The intersection of Atlanta and Paces Ferry roads saw 85 percent fewer morning crashes since $800,000 worth of improvements were completed in 2008, with 66 percent fewer crashes overall, Montanye said.
Overall, the intersection was the site of 86 crashes before the improvements were in place and 29 after, said Paul Giles, a DOT traffic engineer.
Improvements to the juncture included the removal of a center lane and addition of a second left turn lane, which Montanye said made the turn safer by adding a turn-only light allowing more cars to turn left. He said the reduction was sharper in the morning because crashes were more prevalent along the commuter route during that time. The morning commute requires a left turn at that intersection, Montanye noted, while the evening commute funnels drivers into a right turn as they head home in the opposite direction.
He said left turns carry a higher “crash likelihood” than right turns because they force drivers to cross the paths of opposing vehicles.
Faye DiMassimo, director of Cobb DOT, said the study indicates SPLOST projects are making a positive mark on driver safety.
“Time is clearly showing these safety and operational investments have been effective in making our Cobb County residents and roads safer and more efficient,” DiMassimo said. “Even with the improvements, because of the large volume of traffic, we encourage drivers to always be alert and drive defensively.”
An about $1 million roundabout that replaced the four-way stop at Villa Rica and West Sandtown roads in 2008 decreased the wait times of morning commuters by 83 percent, Montanye said, while bringing evening commute delays down by 68 percent. The roundabout shaved an average of 77 seconds off how long drivers waited at the intersection in the morning, Montanye said, and 26 seconds off how long they waited in the evening.
Commissioner Helen Goreham, who represents northwest Cobb, applauded the project, which gave commuters the first county-sponsored roundabout.
“Roundabouts in general improve safety at intersections, and they allow for an increased flow of traffic,” Goreham said.
She said the four stop signs at the old Villa Rica and West Sandtown intersection caused traffic to stall because drivers would get confused about whose turn it was to pull forward.
“(The roundabout) makes for a more safe intersection,” Goreham said.
The segment of Childers Road that runs from Shallowford Road to the Fulton County line received more than $2 million worth of improvements, Montanye said, including updated signage and markings and the addition of sidewalks and crosswalks and alignment improvements. He said the department also flattened the curves of the road to make turns safer, as well as widened lanes to bring the route up to current standards.
Those repairs yielded a 72 percent overall reduction in crashes along the Childers stretch, Montanye said.
Giles said the number of crashes in the area fell from 25 before the improvements to seven after they were completed.
The report also looked at the impact of the $7.4 million in improvements to the portion of Wooton Lake Road that runs between Wade Green and Shiloh roads.
Montanye said those upgrades, which resulted in a 14 percent overall reduction in crashes, entailed widening lanes, smoothing out curves and improving sight distance, or how far drivers can see when making turns along the road. The number of crashes along Wooton Lake fell from 69 to 59 with the improvements, Giles said.
“What we’ve done is, we’ve looked back at projects that’s been completed over three years ago, because we wanted to have three years of data,” Montayne said of the study.
Since construction for many of the transportation projects included under the 2011 SPLOST is still underway, he said the study looked at the previous round of improvements. Transportation officials will likely perform a similar analysis when 2011 SPLOST projects have been finished long enough for their effects to become evident, Montanye said.
While Lee said he was not surprised at the report’s findings, he noted improving road safety remains high on his list of priorities for the proposed list of projects that would fall under the 2016 SPLOST renewal if approved.