How to reverse the direction of traffic on a busy interstate? Very carefully

Credit: David Wickert

Credit: David Wickert

So how do you reverse the direction traffic on a major highway carrying hundreds of thousands of vehicles?

Very carefully, according to the State Road and Tollway Authority.

That agency and the Georgia Department of Transportation are preparing for this month's opening of 12 miles of reversible express lanes on I-75 in Clayton and Henry counties. The lanes are separated by barriers from the general purpose lanes and will allow vehicles to travel north toward Atlanta in the morning and south out of town in the afternoon.

On Thursday, the agencies gave the media a tour of GDOT’s Transportation Management Center (TMC), where they monitor traffic and will control the reversible lanes. But changing the direction of so much traffic isn’t a matter of flipping a switch.

First, overhead signs will alert motorists that the lanes are closed. That will happen around 11:30 a.m. or noon each weekday to prepare for the afternoon rush hour.

Then a series of gates – at least three and as many as seven, depending on the location – will close behind vehicles already in the lanes. The state has sensors that will alert employees at the TMC when cars are still present. But there will also be GDOT Highway Emergency Response Operators on the scene to ensure there are no vehicles or debris on the road.

When it’s clear, operators at the TMC can open the gates for traffic moving the other way.

The whole process will take up to two hours. It will be repeated at around midnight to prepare for the morning commute.

If it sounds like a lot of work, think about what would happen if the lanes were reversed prematurely, opening them to hundreds of vehicles while someone was still driving in the opposite direction.

“We’re going to be very thorough with it,” said GDOT spokeswoman Jill Goldberg.

The reversible lanes will open the weekend of Jan. 28. While you're waiting, don't forget to get a Peach Pass. You'll need one to be able to use the lanes.