The $150 million project, to be paid for with bonds and federal funds, would place new lanes on a 12-mile strip of I-75, on what is now a grass median, between McDonough Road and Stockbridge Highway at the I-675 junction.
The department held two public information open houses in McDonough on Tuesday and Thursday.
GDOT engineer Darryl VanMeter said at Thursday’s event that the combined attendance of about 300 residents weighed in for and against the project.
“The concept of managed lanes is new to Henry County and to this area. It’s a tough concept to explain and get people comfortable with,” he said.
GDOT project manager Loren Bartlett said managed lanes are “any high-occupancy type” travel corridors, but the new lanes would not be restricted to car pools like HOV lanes in metro Atlanta.
The project shares aspects of the I-85 HOT lanes in Gwinnett County, which opened in 2011.
The managed lanes would have tolls that vary with traffic volume and demand, payable with a Peach Pass.
But, unlike I-85, which converted an existing lane to a toll lane, the I-75 project will add new lanes and physically separate them from the existing lanes with a barrier.
“This is a completely different system,” Bartlett said. “This would be buffer-separated. There won’t be any weaving between the two.”
Drivers could enter using either new ramps which will be built or “slip ramps” allowing them to merge from the free lanes.
Morning traffic will be northbound only, toward Atlanta, and evening traffic will be southbound only.
Bartlett said the project will improve travel in the free lanes and up to 12 minutes can be shaved off trip times in the new lanes.
“This should be a very smooth, free-flowing trip,” she said.
VanMeter said the project will relieve congestion at a bottleneck south of the project area.
According to research posted on www.I75express.com, the need for more capacity in that corridor has come about from population growth.
Bartlett said the planners looked ahead to what will be needed in 2037, 20 years after the proposed lanes will open.
All revenue from the tolls, which have not been calculated yet, will go into maintenance and operations, she said.
Plans can be seen at the GDOT District 3 area office, 1001 Highway 19 South, Griffin, through May 5. Through May 9, residents can send in comments at www.I75express.com or email@example.com. The project is scheduled to be sent out to bidders in June. Construction is scheduled to begin in July 2014 with completion in December 2016.