The Minnesota Department of Transportation (and other agencies, too) often put down temporary lines to guide motorists through and around road construction zones. But when the "Road Closed" signs, cones and barrels are taken down, some motorists say remnants of the temporary lines left behind create confusion and lead drivers to blindly change lanes.

That was the case for one motorist who recently witnessed that behavior on westbound Interstate 494 near Cedar Avenue in Bloomington. It prompted him to write to The Drive and say, "How about painting over the old traffic lines?"

While that might seem like a plausible option, painting over old lane markings would be only a temporary fix. When the fresh paint wears away, the confusing markings would show through and the problem would recur, said Tiffany Dagon, a metro district pavement engineer at MnDOT.

The two most common methods MnDOT uses to cover obsolete markings are water blasting and sand blasting. While effective, those methods have drawbacks, too. Water blasting might not get all the paint off, and sand blasting can leave a scar or groove in the pavement. Scars can also be misinterpreted as lane markings, causing confusion again.

One example of that is on the I-94 overpasses near Cedar and Riverside avenues in Minneapolis. Two years ago the bridges were reconfigured from having four lanes to three, and grooves in the concrete indicate where the previous lane markings were. Eventually those will fade and will be less noticeable by summer. Newer grooves, such as those on I-494 near Cedar, will take some time to wear down.

"There is no product made that will completely make it look like there was never a stripe there to begin with," said T.K. Kramascz, director of communications and public affairs for MnDOT's Metro District.

On concrete surfaces, MnDOT has been trying to make it easier for drivers to see lane markings by placing a black strip on either side of white lane markings to make them stand out, Dagon said.

"We do that for contrast," she said. "We try to make it more noticeable so drivers don't follow the scar."

MnDOT monitors the roads and follows up on calls from motorists who report roads or lane markings that are in poor shape.

"We are consistently trying for higher quality [line] removal," Kramascz said. "They are always looking to correct markings that are not clear."

To report poor road conditions or confusing markings, motorists can contact MnDOT at 651-296-3000 or

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Tim Harlow • 612-673-7768 Twitter: @timstrib, @stribdrive