BOSTON – Massachusetts transportation officials say they have discovered some corrosion in the lighting for the Big Dig tunnels in Boston.

Secretary of Transportation Jeffrey Mullan said Wednesday that a 110-pound fixture fell but did not hit any cars.

Mullan said there are about 23,000 light fixtures in the tunnels, and corrosion has been found in fewer than 2 percent. He says there’s no danger to the public, but the state is starting a full review.

The Big Dig was the most expensive highway project in U.S. history and was plagued by cost overruns and design problems.

In 2008, contractors who worked on the project agreed to pay more than $450 million to settle a lawsuit over a fatal tunnel ceiling collapse and to cover costs of leaks and design flaws.