BOSTON — At least 12 tons of concrete fell from the ceiling of this city's Big Dig late Monday night, crushing a woman to death and fueling new questions about the safety of the $15-billion underground highway and tunnel system.
The ceiling collapse in a connector section of Interstate 90 followed a winter in which one of the country's most ambitious urban infrastructure projects was plagued by falling debris, floods, leaking walls and concerns about construction methods in the transportation labyrinth.
Declaring that "people should not have to drive through turnpike tunnels with their fingers crossed," Gov. Mitt Romney said Tuesday that he understood why motorists might be losing confidence in the Big Dig.
"I don't think anyone can feel safe driving through a tunnel system where just last night, someone got killed by a 3-ton piece of concrete falling on their car," he said.
Romney and Massachusetts Turnpike Authority Chairman Matthew J. Amorello have long been at odds, and the tunnel accident only stepped up the battle. On Tuesday, Romney angrily called for Amorello's ouster as head of the agency that supervised the vast Big Dig construction project and now oversees its operation.
State Atty. Gen. Tom Reilly on Tuesday described the area where the collapse occurred as a crime scene, and said the incident could lead to charges of negligent homicide. State police, the U.S. attorney's office and the Federal Highway Administration also promised prompt probes.
The incident also is expected to add a contentious note to the state's gubernatorial race. Independent candidate Christy Mihos, a former member of the Turnpike Authority board, on Tuesday urged Romney to seize control of the agency.
The governor, a Republican who is exploring a 2008 presidential bid, on Tuesday cut short a vacation in New Hampshire to tour the damaged area. Romney also expressed sympathy to the family of Milena Delvalle, a 38-year-old Boston restaurant worker killed in the Monday night accident.
Delvalle and her husband were headed to Logan International Airport to pick up relatives when at least four slabs of concrete -- each weighing three tons -- fell on their car around 11 p.m.
Angel Delvalle, 46, was able to escape through the driver's side window with only minor injuries. His wife was killed instantly, authorities said.
Steel tiebacks that held the 40-foot ceiling sections in place gave way, causing the accident, Amorello said Tuesday. The ceiling panels were set in place in 1999, bolted to the tunnel roof by the tiebacks. At least 17 areas of the Big Dig use similar construction, authorities said.
Standing near the accident site, Amorello said: "Any responsible party will be held accountable for what happened."
Giant slabs of concrete lay strewn on the stretch of highway that leads to the Ted Williams Tunnel. The "Ted," as the tunnel is known, passes under Boston Harbor and ends at Logan Airport. The I-90 connector, opened in 2003, runs under an industrial part of South Boston near the city's gleaming new convention center.
"This is an unacceptable, horrible tragedy," Amorello said. Insisting that "these tunnels are safe," he called the incident "an anomaly" and promised an independent investigation.
But Boston Mayor Thomas M. Menino said: "We don't need a six-month study. We need an immediate reaction and action by the different authorities so that we can reassure the public as they drive into the city or drive over to the airport that the tunnel is safe to go through."
The same worries apparently were on the minds of some motorists Tuesday. The fatal ceiling collapse made havoc of Tuesday's commute hours. Drivers racing to catch planes struggled to find new routes to an airport that lies across the harbor from the city it serves.
Boarding a ferry to catch a plane to Virginia, accountant Mary Sullivan, 52, said the ceiling collapse increased her doubts about the Big Dig.
"What ceiling's going to come down next?" she said. "The inspectors, what were they doing?"
Scott Tarentino, 26, said he wondered about "all the billions of dollars they have spent so far" on a project that was under construction for 15 years.
"At first I was like, oh, they know what they are doing," said Tarentino, who sells paving materials. "But after so many things keep happening, you wonder if those people know what's going on."
The Big Dig has long been faulted for cost overruns, questionable construction and what Romney on Tuesday called "an ongoing pattern of mismanagement." In May, six men who supplied concrete to the Big Dig were charged with providing substandard materials.
Boston University journalism professor Fred Bayles, who covered the Big Dig as a reporter starting in the 1990s, said: "The Big Dig is now officially a boondoggle. With this terrible accident, it becomes not only a boondoggle, but a dangerous, and perhaps criminal boondoggle.
"Most huge public works projects have glitches and cost overruns.... But with last night's incident, the Big Dig goes beyond harmless but costly mistakes."
The Big Dig was shepherded through Congress by Massachusetts Sen. Edward M. Kennedy and the late speaker of the House of Representatives, Thomas P. "Tip" O'Neill. The network of subterranean roads and tunnels replaced a decrepit elevated expressway that marred the city's waterfront.
Building the Big Dig, a seven-mile system, has been compared to constructing the Panama Canal -- under a major American city. The last major section of the project was completed this year, but some construction continues.