Transportation officials displayed examples of the corroded frames that are supposed to hold the panels.
Transportation officials displayed examples of the corroded frames that are supposed to hold the panels.
Eric Moskowitz/Globe Staff

Workers removed 117 wall panels in the Callahan Tunnel overnight due to concerns that the frames holding them up had become corroded, raising the risk that they would fall into the roadway, transportation officials said this morning.

Dozens of workers spent seven hours examining the panels overnight, performing “pull tests”—pulling on them from the top and bottom and to see if they were loose. If there was “any degree of looseness,” the panel was removed, said Frank DePaola, highway administrator for the state Department of Transportation.

“We’re confident that the remaining wall panels are firmly secured, and we feel that no one should have any concerns about the safety of those panels going forward,” DePaola said at a news conference at the department headquarters.

Advertisement - Continue Reading Below

The inspection was ordered after one panel fell into the roadway Friday night, tying up traffic for several hours. Three other panels were also immediately removed.

The panels, 4 feet by 9 feet and weighing about 100 pounds, were installed about 1990. They are not only decorative and easier to clean than the concrete walls of the tunnel, they are also reflective, improving the lighting in the tunnel, DePaola said.

DePaola said that in the past, the panels have been inspected visually at least annually. Now, he said, at least quarterly, workers will perform the pull tests to make sure the panels are firmly attached.

State officials are in the process of planning a series of renovations to the Callahan that will take place January to April 2014, DePaola said.

Officials displayed some of the corroded frames and bolts at the news conference. They noted that the frames are made of galvanized metal and the bolts are stainless steel. They said it was possible that there was some kind of reaction due to the different kinds of metal, but much of the problem was likely simply age and moisture. The frames are about 20 years old.

The tunnel reopened at about 4 a.m., said Sara Lavoie, spokeswoman for the Massachusetts Department of Transportation.

The panel that fell into the roadway Friday did not hit any vehicles or injure anyone.