BOSTON -- Bay State motorists who thought they were safer taking the Callahan or Sumner tunnels following this summer's fatal Big Dig accident at the entrance to the Ted Williams Tunnel might want to think again.

Gov. Mitt Romney said Tuesday that an intensive Big Dig safety audit launched after an Interstate 90 ceiling panel fell and killed a Boston woman in July shows that both the Sumner and Callahan tunnels also have significant structural problems that could pose safety risks to drivers.

Although Romney insisted the older tunnels leading under Boston Harbor to Logan International Airport are "a lot safer than they were three months ago," other officials said they were "surprised" the older tunnels were in such bad shape.

The public is not in any immediate danger using the tunnels, Romney said, in large part because of the recent safety inspections and subsequent repair work that has taken place.

"Finally, we're getting a chance to see the problems. We're looking past the panels and looking at what's behind them," Romney said. "It reminds me a bit of somebody who took the siding off their house and saw that the structural members, the two-by-fours, were rotted, and they said, 'Well, better put up some new siding quick.'"

"This suggests to me that we're finally taking the siding down on our highway system ... and we're recognizing there's been a lot of rot under those panels that needs to be repaired. And they may well have known about it but just didn't choose to tell people about it," Romney said.

In a Statehouse presentation, Romney said the Sumner Tunnel, originally built in 1934, and the Callahan, built in 1961, had renovations and repair work done in the 1990s, when some ceiling panels were replaced with less heavy panels using adhesive bolts similar to what was used in the I-90 connector. But the repair work apparently caused more problems, because the aging concrete inside the tunnels was and is falling off in chunks and the rebar underneath is rusted.

According to the safety inspections, when renovations were done inside the tunnels, the corroded concrete and rebar were not repaired before new ceiling struts were attached to the unstable materials. As a result, there could be safety issues with some of the ceiling panels.

"The anchors, these brackets, are not embedded as deeply as you'd like them to be," Romney said, adding that there is "some risk associated with panel strength."

Inspectors also found that there were no diagonal struts placed in the Callahan ceilings to cushion any kind of seismic or motion shifts.

Romney said bolts had also slipped in the Callahan, and 418 of them were repaired or remediated since this summer.

The governor said it was clear that the Sumner was going to require major, massive repairs after the other Big Dig tunnels were fixed, and all the tunnels would require frequent and regular safety inspections.

"The Sumner's condition is such that a long-term structural repair is going to have to be done," he said. "This is not something which is going to be repaired in the evenings on occasion. This is a major project to reline and repair the inside of that tunnel system."

He said the state would likely have to pay for the additional repairs to the two older tunnels. He said it wasn't clear yet how much they would cost. He also said the audit did not look at who was responsible for the substandard renovations to the older tunnels because the main priority of the audit was to identify public safety issues.

Other Repair Work

As far as the other Big Dig repair work that is under way, Romney said work on Ramp D is now 48 percent complete and contractors hope to have all the work finished by the end of October. That ramp connects the Ted Williams Tunnel to Interstate 93 north and south and is completely closed right now, Romney said.

He said that on I-90 eastbound, work is progressing to open it from one to two lanes but there was no time frame given for when the work will be completed. He said the same goes for I-90 westbound lanes.

Romney said some of the "easy" repairs that have taken place so far included reinforcement of vaulted abutment panels where brackets mounted to the ceiling had bolts that were coming loose. He said some roadway signs and traffic signals also had bolts coming loose or had been damaged where steel had rusted and aluminum had cracked.

The repairs were sparked by the death of Milena Del Valle, 39, when three-ton ceiling panels fell on her car in the eastbound I-90 connector tunnel in July. Her husband, Angel, survived and the family has filed a wrongful death suit against the state. The accident sparked a public outcry over problems associated with the $14.6 billion Big Dig project, which has been plagued by cost overruns, leaks and mismanagement.