The head of the agency overseeing Boston's Big Dig highway project ordered a review of the entire highway system Wednesday after investigators looking into the fatal collapse of concrete ceiling slabs found 60 more questionable areas inside the same tunnel.

About 12 tonnes of concrete ceiling panels collapsed on a couple's car Monday, killing Milena Del Valle but sparing the life of her husband, Angel Del Valle.

Emergency workers at the scene of a tunnel ceiling collapse in Boston that crushed part of a car, shown at rear, killing passenger Melina Del Valle.
(Associated Press/Michael Dwyer)

Initial inspections after the accident revealed dozens of signs of bolts loosening and other potential failures in the eastbound connector tunnel, part of the main route to Boston's Logan Airport, Turnpike Authority officials and the Big Dig project manager said.

There were trouble spots in the westbound lanes of the tunnel as well, they said.

"We're evaluating each of these individual sites," said Matthew Amorello, chairman of the Massachusetts Turnpike Authority.

However, he added: "The tunnel system is safe."

There had been plans to reopen the connector tunnel Wednesday, but Amorello said it would remain closed indefinitely to ensure motorists' safety.

Del Valle's death could lead to charges of negligent homicide, said Massachusetts Attorney General Tom Reilly, who is treating the section of Interstate 90 eastbound as a crime scene.

Contractors' work under microscope

In a related development, U.S. Attorney Michael Sullivan said federal investigators are looking into whether contractors who worked in the area of the collapse actually delivered the goods and services they promised.

Sullivan told the Associated Press that a year-long investigation by his office into the massive highway project is focusing on the section of a highway tunnel where Del Valle died.

Sullivan's office brought the first criminal charges in the trouble-plagued project in May, accusing six men who worked for its largest concrete supplier of falsifying records to hide the inferior quality of concrete.

"We obviously want to identify any public safety risks … but also to ensure that what the government paid for — through tax dollars — is in fact what was delivered," Sullivan said.

Falling cement 'was like a bomb'

Angel Del Valle, 46, and his 38-year-old wife were driving to the airport Monday night to pick up relatives when four of the slabs dropped on their car just after 11 p.m.

"It was like a bomb," Angel Del Valle, who was able to climb out a window to safety, told the Boston Herald. "Everything was falling. It was too fast. I couldn't stop. I couldn't do anything."

His wife was on the passenger side, which bore the brunt of the damage. There was no way to pry open her door, he said.

Authorities immediately began checking at least 17 other areas with similar steel "tiebacks," which officials believe failed to hold the ceiling panels in place in the tunnel Monday night.

Massachusetts governor promises action

Gov. Mitt Romney pinned much of the blame on the Massachusetts Turnpike Authority and promised to take legal action to oust Amorello as its chief. He compared the situation to the replacement of former Federal Emergency Management Agency head Michael Brown after Hurricane Katrina.

"People should not have to drive through the Turnpike tunnels with their fingers crossed," said Romney, a longtime critic of Amorello.

The highway project, known formally as the Central Artery and Third Harbor Tunnel project, buried Interstate 93 beneath downtown and extended the Massachusetts Turnpike to the airport.

It has gained nationwide notoriety for its soaring costs, years of traffic snarls, the criminal investigation into the concrete suppliers and problems with leaks that sprouted in another of the Big Dig tunnels.

The section that collapsed was near the entrance to the Ted Williams Tunnel, which runs under Boston Harbor to Logan International Airport. That segment of the tunnel was completed in 1995-96, but ceiling panels were installed in 1999.

Modern Continental, the contractor of that portion of the project, issued a statement that its work "fully complied with the plans and specifications provided by the Central Artery Tunnel Project. In addition, the work was inspected and approved by the Central Artery Tunnel Project."

Andrew Paven, a spokesman for project manager Bechtel/Parsons Brinckerhoff, said the company was working with the Turnpike Authority to help pinpoint the cause and prevent future accidents.