Two months after a 110-lb light fixture fell onto a roadway along Boston’s Big Dig highway project, Massachusetts Dept. of Transportation inspectors have found some corrosion in the 23,000 lighting fixtures that line the Central Artery tunnel. In the wake of the resignation of a highway administrator following a delay in notifying the public about the fixture, the agency’s operational procedures are under scrutiny

“I have acknowledged our failure to alert the public in a timely manner and the lapse in our internal communications, which we are currently working to address,” state transportation Secretary Jeffrey Mullan says. “We are continuing to gather facts in our review of this matter and will provide an update upon completion of that review.”

Adam Hurtibise, MassDOT spokesman, said inspections of the tunnel light fixtures are complete, and about 300 lights—less than 2% of some 23,000 in the tunnels—displayed some corrosion. After the incident, MassDOT inspectors determined there is corrosion. “Preliminary findings indicate that water and salt may have accelerated this corrosion process,” he says.

MassDOT hired Massachusetts Material Research Inc. to help determine the corrosion’s source. The West Boylston, Mass., company declined to provide ENR with additional details on the incident.

The 110-lb light fixture fell from the ceiling on the morning of Feb. 8 onto the roadway in the O’Neil tunnel. No injuries or property damage was reported.

In a press conference on April 1, Mullan said Frank Tramontozzi had left his position as acting highway administrator, a post he assumed on March 2, as well as his position as chief engineer for the highway division. Tramontozzi did not reply to requests for comment.

In a March 25 internal MassDOT communications review, Tramontozzi claimed he was at an offsite meeting on Feb. 9 and says he was not notified about the fixture incident until Feb. 24 by Helmut Ernst, a highway director. Tramontozzi failed to notify Transportation Secretary Jeffrey Mullan until March 8. However, Ernst claims he telephoned Tramontozzi about the incident and ordered visual inspection of the lights on Feb. 9, the review notes.

Some experts have questioned how MassDOT’s technical support contractor—Los Angeles-based AECOM, which collected $4.5 million under a three-year contract—could have missed the problem. Hurtibise says AECOM was hired to inspect the lights and perform additional work on the tunnels. While the state has not openly criticized AECOM’s performance, he says, MassDOT has changed the inspection protocols to require a hands-on inspection of the lights. Previously, a visual inspection sufficed.

Requesting anonymity, a structural engineer with knowledge of tunnel inspections says the cause of the incident “appears to be a case of very localized corrosion.”

Based on a New England Cable News video clip from March 16, an aluminum lighting support rod in the tunnel appeared to be in good condition, the engineer says, except at the point lighting fixture clips are attached.