The 30 miles of reversible lanes on I-75 and I-575 in Cobb and Cherokee counties opened last September. In their first eight months, motorists took more than 4.2 million trips on the lanes, GDOT says.

Traffic in the new toll lanes has moved 30 percent faster than traffic in the general purpose (or “free”) lanes, the agency says. But vehicles in the regular lanes also have benefited.