Motorists on Ga. 400 in Forsyth County are doing a double-take these days. And it's not over a fender-bender or abandoned clunker.

Commuters are turning their heads — and apparently scratching them, too — over what looks like a sidewalk being laid down the median.

Phil Skinner/AJC (ENLARGE)

Sidewalks? Nope, they're concrete pads in the GA 400 median in Cumming.

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Who would want to take a stroll, or go for a jog, between tens of thousand of screaming cars and trucks?

Officials with the state Department of Transportation said they've repeatedly tried to reassure the public that they've not lost their minds.

They are not putting a sidewalk on Ga. 400.

The long stretches of concrete that commuters see are part of the cable barrier being installed on 13.3 miles of Ga. 400 the between McFarland Parkway and Keith Bridge Road, to prevent cross-over wrecks.

Similar barriers were installed last summer on I-85 in Franklin and Hart counties and got the same reaction. Others are going up on I-985 between I-85 and Jesse Jewel Parkway in Gwinnett and Hall counties, starting in the next couple weeks, and on I-85 through Gwinnett, Barrow, Jackson and Banks counties later this summer.

But the inquiries keep coming to the DOT, like this recent e-mail from a commuter who travels Ga. 400 five days a week from Cumming to work in Alpharetta.

"I do not understand the purpose of what appears to be 'sidewalks' being installed in the median!" the person wrote. "As if traffic wasn't already bad enough in this area (especially in the afternoons), this construction of what appears to be a project which will do nothing to ultimately improve the flow of traffic in the area is annoying, to say the least!"

Teri Pope, a DOT spokeswoman, said she's been surprised that so many people have jumped to the wrong conclusion.

"That just doesn't make sense. Walking on a limited-access state route like 400 or interstate is illegal — not to mention that it's not wise," Pope said. "We're all about safety."

The concrete that's been laid is about half the width of a standard sidewalk. But it's got a big purpose: helping to hold steady the tension cables and steel posts that are designed to keep a careening car from crossing the median and hitting vehicles traveling in the opposite direction.

Already in Franklin County, the cable barrier is credited with stopping a tractor-trailer that was hauling a bunch of cars, weighing over 40 tons, Pope said.

"This barrier will stop anything that doesn't get airborne! " she said.