[aaaaaaaabbbby]

Woman killed in Boston Big Dig tunnel fall

Kansas City Star
KEN MAGUIRE
Associated Press

BOSTON - Three-ton concrete panels fell from the ceiling of the city's Big Dig tunnel, killing a woman in a car and shutting down a section of the massive building project that has become both a central route through the city and a source of construction concerns and cost overruns.

The woman was a passenger in a car hit by debris from the ceiling late Monday, authorities said. A man believed to be the driver was able to squeeze out and was taken to a hospital with minor injuries, authorities said.

Authorities say safety has not been compromised by problems with the $14 billion Big Dig highway project, which buried Interstate 93 beneath downtown and extended the Massachusetts Turnpike to Logan Airport.

Massachusetts State Police said that stretch would be closed indefinitely while authorities clean up debris and inspect the area.

In a news conference early Tuesday, Massachusetts Turnpike Authority Chairman Matthew Amorello said the ceiling collapse was caused by a steel tieback giving way. The tieback held a 40-foot ceiling section in place over Interstate 90.

"There was a snapping sound heard," Amorello said. "One of the tile panels from the roof released. It caused a series of panels to be released."

Amorello said he's confident there is only one 200-foot section of the Big Dig project where the type of tieback that failed was used. Those ceiling panels were erected in 1999 and the contractor was Modern Continental, he said.

In that section, the tiebacks are bolted to a concrete ceiling.

"Any responsible party will be held accountable for what happened," Amorello said. "This is an unacceptable, horrible tragedy."

There was no answer at Modern Continental's office on Tuesday morning before business hours.

The accident happened about 200 feet from the end of the connector tunnel. The site is near the entrance to the Ted Williams Tunnel, which goes under Boston Harbor to Logan International Airport.

Shortly after the accident, at least three large pieces of debris, tilted slightly at one side, were lying across a lane of the roadway about 100 feet from the end of the connector tunnel.

There have been water leaks in parts of the tunnel system and at least one incident when smaller amounts of dirt and debris from an airshaft in another section of the tunnel system fell onto travel lanes, causing minor damage to cars.

In May, prosecutors charged six current and former employees of a concrete supplier with fraud for allegedly concealing that some concrete delivered to the Big Dig was not freshly mixed.

State and federal officials said any effects on maintenance would likely be long-term, and did not pose an immediate safety threat.

Amorello said preliminary investigation shows that the quality of the concrete was not to blame for the fatal accident Monday night.

Copyright

[ResuNezily]

CNN


Firefighters inspect part of a tunnel ceiling
in Boston that collapsed Monday night and killed a woman.

[sueplydup]

CNN


Firefighters inspect part of a tunnel ceiling
in Boston that collapsed Monday night and killed a woman.

I think they replaced the Queens midtown with a precast ceiling.

[VIAGRA-VIAGRA]

Yikes.

[denSmumbSes]

Collapse Slideshow

Officials React Slideshow

[KacypeJeope]

Emergency crews prepare to remove the crushed car trapped underneath
steel ceiling plates of the I-90 E extension tunnel.(Herald photo by Matthew West)


An FBI investigator pointed to an anchor bolt while investigating the debris
in the tunnel yesterday. (Essdras M. Suarez/ Globe Staff)


Workmanship and design of tunnel are called into question
Problems with bolts, glue found in other tunnel in '98
By Scott Allen and Sean P. Murphy, Globe Staff | July 12, 2006

Investigators unraveling how concrete ceiling panels cascaded onto a car in one of the Big Dig tunnels should focus on some basic, troubling questions about the way the tunnel ceiling was built, civil engineers and highway construction specialists said yesterday.

Officials from the Massachusetts Turnpike Authority suspect that the accident that killed Milena Del Valle began with the failure of a single steel hanger that helped hold up the concrete ceiling, setting off a chain reaction that caused other hangers to fail and send 12 tons of concrete to the highway surface as Del Valle's husband drove underneath.

Now, federal and state investigators are looking into the possibility that there was some defect in the way the hangers were manufactured or secured to the roof of the tunnel connecting the turnpike to the Ted Williams Tunnel. A 1998 report from the state Office of the Inspector General documented numerous problems with the bolts and glue used to secure the ceiling in the Ted Williams Tunnel, including the use of bolts that were too short and trouble with an epoxy used to glue the bolts into the concrete.

The inspector general's report was written before construction of the ceiling section that later collapsed, and it's not clear whether the same methods were used. However, Governor Mitt Romney said the report should have served as a warning.

``That would suggest to a layperson like myself that a very high degree of care should have been taken in inspecting that section of the ceiling, and I don't know whether that care was given or not," said Romney, referring to the I-90 connector tunnel at an afternoon press conference.

The tunnel section was inspected before it opened to the public in January 2003 and another inspection was ``in the process" when the accident happened, Turnpike Authority chairman Matthew J. Amorello said yesterday. He said turnpike records from Modern Continental, the company that built the tunnel, show that the hangers were individually inspected and tested when completed.

Big Dig officials say there is no indication of a link between the ceiling collapse and previous problems such as leaks and use of inferior concrete.

Civil engineers said the questions must go beyond the quality of workmanship to the tunnel's design: Why were the concrete panels so heavy, weighing 2 1/2 to 3 tons apiece? Why were they there at all, since there was already a higher tunnel roof? And why did the failure of a single steel hanger send six to 10 of the slabs crashing down?

Initial reports from eyewitnesses and investigators indicate the accident began with a loud snap as a steel hanger gave way and the other three holding up a 40-foot steel bar couldn't handle the extra weight.

``I can't imagine anybody signing off on a design of suspending 3-ton concrete panels such that the failure of any one hanger would lead to 12 tons of concrete coming down on the highway," said Steve Banzaert , who teaches a course in ``spectacular failures in engineering" at MIT.

A spokesman for Modern Continental said the company would not answer specific questions. The company issued a statement saying it promised to cooperate with the investigation, while defending its workmanship. ``We are confident that our work fully complied with the plans and specifications provided by the Central Artery Tunnel Project," read the statement, adding that Big Dig officials inspected and approved the tunnel ceiling.

Bechtel/Parsons Brinckerhoff, the consultant that managed the design and construction of the project for 20 years, also promised to work with the Turnpike Authority to determine the cause.

The ceiling that collapsed -- inside the eastbound lane of I-90 under South Boston -- is structurally similar to a drop ceiling, with a lower ceiling suspended from the original one. However, instead of the light fiber panels used in homes, the drop ceiling in the Big Dig tunnel is composed of 20-by-40-foot slabs of concrete. The slabs rest on 40-foot-long steel bars that are suspended from the original concrete ceiling by steel hangers. The hangers are connected directly to the upper ceiling by a combination of bolts and glue.

Although such drop ceilings were built elsewhere in Big Dig tunnels, a 200-foot stretch where the accident occurred and the Ted Williams Tunnel have ceilings constructed differently from those in the rest of the connector and the Interstate 93 tunnel, which were built later, Amorello said. In the I-93 tunnel, a beam with ready-made steel connection points was embedded inside the concrete when it was poured to make it easier to suspend the ceiling. But in the affected section, crews didn't install the drop ceiling until 2000, five years after the original ceiling was built, forcing them to use another approach.

``They used this system of drilling in bolts and bolting it in with epoxy, and that's what we're investigating," Amorello said.

Michael P. Lewis , the state Big Dig project manager, said at a morning press conference that this was ``an approved method."

``It was actually the method used in the entire Ted Williams Tunnel," he said. ``It's a well-known way of attaching anchors to concrete structures."

One state official who has been briefed about the investigation said one focus is on whether ``a cheaper, quicker" ceiling design was approved by Big Dig officials for the turnpike section without adequate consideration of the possible consequences. The official is not authorized to speak publicly about the investigation.

This isn't the first time that investigators have looked at the quality of Big Dig drop ceilings. In 1998, Inspector General Robert A. Cerasoli said the project wasted $800,000 attaching hangers to the ceiling of the Ted Williams Tunnel because designers hadn't foreseen the need to attach hangers to the original concrete ceiling.

Although Cerasoli was focused on the needless cost of drilling and redrilling holes, he said yesterday that he is also concerned that low-quality work generally could have compromised tunnel safety. During construction, Cerasoli's report says, the contractors had trouble with the epoxy -- workers didn't give it time to cure properly or improperly cleaned holes, and the epoxy's manufacturer suspected the contractor was not mixing it properly. In a first set of tests, eight bolts failed out of 50.

Peter Zuk , the former state Big Dig director, had promised in a written response to the report to use a better way of fastening the steel hangers in the future, but the letter didn't describe the changes, and it was unclear yesterday whether they happened. However, Modern Continental's contract was modified several times in 1999, at a cost of almost $600,000, to allow for changes in the installation of ``adhesive anchors for ceiling struts" in the I-90 tunnel, according to state records.

``They really ought to have an independent group come in and evaluate all of these tunnels," said Cerasoli, inspector general from 1991 to 2001.

One construction industry specialist said he questioned whether the drop ceiling in the turnpike tunnel was needed at all. Turnpike officials said yesterday that the drop ceiling was needed to improve the flow of fresh air into the tunnel and move exhaust fumes out. But the specialist, who is familiar with the connector tunnel design but asked not to be identified, said the drop ceiling was there mainly for aesthetic reasons, to hide fans. He said the section is vented by open air entrance ramps only about 200 feet away.

Amorello said engineers will consider reopening the tunnel without any panels in the section where the accident occurred. He said that, if ``we can do without it, then we are going to do without it."

Gareth Cook of the Globe staff contributed to this report.

[expiclefich]

This is what PaulC from ArchBoston has to say about it:

About a year before the big dig tunnel opened I got a private tour of the project from one of the quality engineers on the project. All he did was complain about the poor workmanship and inferior material they were using and how every time he reported his findings he was ignored. Half way through the tour I decided he was some kind of malcontent. Guess I was wrong.

I would expect we are yet to find out how badly this project was done. Modern Continental had about 25 percent of the contracts.

[Forex Autopilot]

Who thought a concrete drop ceiling was a good idea?

[Erexecike]

The only functional property to the drop ceiling mentioned so far is found in the first graphic Jasonik posted -

"Concrete panels attached by metal tiebacks form a drop ceiling used to help ventilate the tunnel."

[Wymdqcvb]

If they wanted a drop ceiling I'm very surprised they didn't go with metal.

[BrifsGefel]

Man, this is such a sad story. I smell a BIG ass lawsuit coming.

[sirmzereigMix]

Workmen yesterday loaded steel panels onto a lift for installation,
while behind them lay a section of a concrete panel and its supports that
had been removed from the I-90 connector. (George Rizer/ Globe Staff)

Need for heavy panels was debated

By Scott Allen, Globe Staff | July 13, 2006

The engineer who oversaw completion of the Interstate 90 connector said in an interview with the Globe yesterday that he questioned the need for heavy concrete panels in the tunnel's drop ceiling when he came on the job, but that he didn't press the issue with senior Big Dig officials, because the ceiling work was already well underway and he was persuaded it was being done safely.

Several of the 2 1/2- to 3-ton slabs crashed to the roadway Monday night, killing a 38-year-old mother of three and closing the tunnel indefinitely.

Officials of the Massachusetts Turnpike Authority said yesterday that the concrete panels were part of the tunnel's ventilation system and needed to be heavy to remain still when powerful fans operated at full power.

But some have questioned whether the slabs were needed at all, since their main purpose was to improve air circulation and fresh air was already entering at the entrance to the tunnel 200 feet away.

James Bruno, who served as project manager for Modern Continental on the $91 million contract to complete the connector tunnel, said that he and other construction managers suggested in meetings with Big Dig officials using lighter material for the ceiling, pointing out that the side walls of the tunnel are made of thin metal.

``You're just controlling air here; you don't need heavy concrete slabs," said Bruno, now a senior project manager at Beacon Consulting Group.

But he said senior Big Dig officials were not interested in using a lighter material, because doing so would have required many more supports to prevent the ceiling from vibrating. A lighter material is generally less sturdy and more likely to shift in the face of wind or vibration from traffic.

``When I came to the job, it was roughly 30 percent done," Bruno said. ``They were already doing it this way . . . So I stepped in and said OK. "

He said he dropped the issue after he saw that work crews were doing a careful job installing the ceiling, testing many of the bolts with a device that pulls on them to test their resistance.

Bruno stressed that he feels the tunnel was built safely, in spite of Monday's accident. ``It was excellent people doing excellent work," he said.

``We really tried to do the highest quality job and the safest job," said Bruno, adding that all the workers were well aware that the tunnel ceiling would be suspended over people's heads for decades to come. ``There were no shortcuts."

A number of government agencies are focusing on whether shoddy workmanship or design flaws in building the ceiling contributed to the accident. Much of the attention has focused on durability of the bolts-and-glue combination that hold up the steel frame on which the concrete ceiling panels rest.

The drop ceiling in the nearby Ted Williams Tunnel is affixed to the actual ceiling in a similar fashion, but Turnpike Authority officials said yesterday that panels in the connector tunnel ceiling were at least six times heavier than ones used in the Ted Williams Tunnel, which were a thin composite of metal and concrete that weighed about 800 pounds each.

But Michael P. Lewis, the state's Big Dig project manager, said during a press conference yesterday that the panels in the I-90 connector needed to be heavy for stability in the face of ``hurricane force winds" generated by fans near the roof of the tunnel. In an emergency, such as a tunnel fire, Lewis said, the fans would be turned up to maximum velocity to bring in fresh air, requiring a heavy drop ceiling that would not vibrate.

``We all know from watching the Weather Channel what happens to something like a piece of plywood or something light in hurricane force winds," Lewis explained.

The air flow is less forceful in the Ted Williams Tunnel, Lewis said, and its drop ceiling was primarily for aesthetics.

Now that the concrete panels are all being removed from the connector tunnel as part of the safety review, Turnpike Authority chairman Matthew J. Amorello has said he will consider reopening the tunnel without any drop ceiling at all. Some industry observers have said all along that the drop ceiling was mainly cosmetic, concealing the fans from the drivers below.

As project manager for the last phase of connector tunnel construction, Bruno was primarily responsible to keep the work running smoothly and as close to schedule as possible, rather than to change design of the project.

Ultimately, the tunnel opened to the public in 2003, and final construction work was completed in late 2004, more than a year behind schedule. However, Bruno said the time pressure didn't affect the quality of the work on the drop ceiling.

``We knew it was going to be hanging over the roadway," he said. ``We didn't fool around."

Scott Allen can be reached at allen@globe.com.

[icyfreshy]

Thursday, July 13, 2006
Engineers find 240 more “suspect bolts” in tunnel
By Andrew Ryan, Globe Correspondent

Engineers investigating the collapse of the Interstate 90 connector tunnel said this afternoon that they have found about 240 more "suspect bolts" securing concrete ceiling tiles similar to those that fell Monday night and crushed a woman to death.

In some areas, inspectors have found a gap of at least 1/16 of an inch between the steel hangers and concrete, according to Michael P. Lewis, the state's Big Dig project director.

“It may not be a failure,” Lewis said, speaking at an afternoon press conference. “It may just be a natural gap.”

Massachusetts Turnpike Authority Chairman Matthew J. Amorello said workers have already removed 12 sections of the concrete tiles and plan to remove tiles from another 20 areas in the eastbound and high occupancy lanes.

Officials did not give a timetable for how long the tunnel would remain closed and said it may open in sections, a process that could take weeks.

The 200-foot tunnel, which links Interstate 93 to the Ted Williams Tunnel, has been closed since late Monday night. Bolts in the ceiling failed and 12 tons of concrete cascaded into the tunnel and crushed a car, killing Milena Del Valle, 38. Her husband, Angel Del Valle, 46, escaped with minor injuries.

Officials said that all the sections of the tunnel with the problem bolts have been closed since the accident.

Earlier today, Secretary of Transportation John Cogliano said that the ceiling above the westbound lanes in the connector tunnel was in “worse shape” than the concrete ceiling panels above the eastbound lanes.

Cogliano made the remark at a press conference at which Governor Mitt Romney announced he was filing emergency legislation to take control of the investigation of the Big Dig tunnels, a move that has support of legislative leaders.

Romney said he wants inspectors and engineers examining the connector tunnel to report to Cogliano, instead of the Massachusetts Turnpike Authority.

“We want to have our personnel watching on site, making a determination as far as go or no go as far as the tunnel re-opening,” Romney said. He added: “The current leadership of the turnpike authority has lost public confidence, pure and simple.”

Romney wants to take control of both the immediate investigation of the ceiling system and a longer term inspection of the entire Big Dig tunnel system. The governor said he wants access to Turnpike Authority records, designs and inspections.

Romney’s legislation calls for $20 million to complete a “stem to stern” safety audit of the entire Central Artery/Tunnel project. The measure would take effect immediately if passed by the Legislature.

Posted by the Boston Globe City & Region Desk at 06:05 PM

[GinaIsWild]

Amorello's head's about to roll. Who says we don't do beheadings in this country?

[turbutbamethyg]

Hmmm... So, how's traffic in Boston these days?

[cingularring]

It takes four times as long to get anywhere. You have to roll through tiny surface streets in the centre of the city to get to the old airport tunnels, and unpredictable road closures tend to be conveniently timed for the start of rush hour. Every intersection has a coterie of police. It's been a fun few days here.

[DoterrFor]

NTSB team coming to Hub tonight
By Julie Mehegan/ Breaking news
Thursday, July 13, 2006 - Updated: 06:51 PM EST

The federal agency that investigates plane crashes and train derailments is sending a six-person civil engineering team to Boston tonight in the wake of the Big Dig ceiling collapse that killed a Jamaica Plain woman on Monday.
An aide to U.S. Rep. Michael Capuano (D-Somerville) said the National Transportation Safety Board is sending the director of its highway safety group along with the engineering team.
It is unclear exactly what role the NTSB team will play at this stage of the investigation into the collapse of the ceiling in the I-90 connector tunnel. Earlier today, Capuano wrote to the agency seeking an independent inquiry into the deadly collapse. Capuano said the letter was signed by the entire congressional delegation.
“I can’t think of anybody who doesn’t have a conflict, or the appearance of a conflict,” Capuano said earlier today. “This is the only agency I can think of.”
NTSB is an independent government agency that investigates transportation disasters. Agency officials could not be reached for comment.

[Klorissana]

Problems not new for the project's largest contractor
By Christopher Rowland, Globe Staff | July 14, 2006

Modern Continental Construction Co. has performed work that resulted in some of the Big Dig's highest-profile problems: chronic tunnel leaks, defective walls, and now a flawed ceiling that fell and killed an automobile passenger Monday, rocking public confidence in the safety of the $14.6 billion tunnel complex.

It has been a long road for a company that got its start building sidewalks in Peabody in the 1960s, then grew into the biggest contractor on the Big Dig and one of the largest construction companies in the country. But its rapid growth faltered; the company was close to a bankruptcy filing; and it lost its independence. Now its road and heavy construction business has been tarnished by the very project that fueled its success.

Authorities have not established whether design or construction or both are to blame for the ceiling collapse. But Jordan Levy , a former board member of the Massachusetts Turnpike Authority who was highly critical of the project during his tenure, said Modern Continental's deep financial problems, cost overruns, and poor workmanship have left a lasting legacy.

``The general public will see them as responsible for doing shoddy workmanship on this project that caused the death of a person and destroyed the credibility of this project," he said.

Since Monday's accident that killed Milena Del Valle, 38, of Jamaica Plain, Modern Continental has declined to make executives available for interviews. In a prepared statement, the company said it performed its job correctly and followed design specifications.

State Senator Marc R. Pacheco -- chairman of the Senate Post Audit and Oversight Committee, which authored a blistering critique of Big Dig supervisors in 2004 -- said Modern Continental's performance is part of a broader pattern of oversight problems on the project that resulted in substandard work.

While Pacheco's 2004 committee report focused much of its ire on the project manager and designer, Bechtel/Parsons Brinckerhoff , the contractors performing the work also share the blame, Pacheco said. He cited a cozy atmosphere between state supervisors and the designers and contractors hired by the state.

``There was less-than-arms-length relationships between the hierarchy that was overseeing the Big Dig and the contractors that were doing work on the job," including Modern Continental, he said.

Andrew Paven , spokesman for Bechtel/Parsons Brinckerhoff, declined to comment.

Modern Continental has collected an estimated $4 billion in Big Dig contracts since the early 1990s. Nonetheless, the company teetered at the edge of bankruptcy in 2004, the same year that the Big Dig sprang its biggest leaks and the public learned that some tunnel walls were poorly constructed.

The company had invested in a wide variety of businesses, from restaurants to healthcare, and has ventured into heavy construction projects as far away as California and Brazil, leading the Conservation Law Foundation and other groups monitoring the Big Dig to speculate that the company had become overextended.

To avoid a default and the resulting chaos it would inflict on the Central Artery project, the state helped arrange a merger with another large Big Dig contractor, Jay Cashman Inc. Cashman now controls Modern Continental, which still maintains its own corporate headquarters on Memorial Drive in Cambridge.

Strong support for the merger with Cashman came from Modern Continental's insurance carriers, which would have been left with the responsibility of hiring another contractor to finish the work.

The company was founded by Lelio ``Les" Marino with a $4,000 sidewalk contract in Peabody in 1967. But it was not until he won huge Big Dig contracts in the early 1990s by submitting exceptionally low bids that the company really grew. Just two months after state officials disclosed the merger in late 2004, Marino died after suffering from stomach cancer and heart problems.

Also in 2004, the state barred the company from bidding on major highway contracts because of delays in another state project, the $400 million job to widen Route 3 from Route 128 to the New Hampshire border.

Under Marino's leadership, Modern Continental ran into a variety of other problems. In 1998, it agreed to pay $500,000 in penalties to state and federal authorities after a former MBTA resident engineer was indicted on charges of accepting free construction work and building materials from a vice president of Modern Continental who was Marino's nephew. As part of the settlement, Modern Continental agreed to set up a training program to teach business ethics to its employees.

On the Big Dig project, Modern Continental won state work with low bids but then returned to the state with demands for more money because costs were higher than expected.

In other cases, the state officials negotiated a series of global settlements of tens of millions of dollars with Modern Continental to handle the company's demands for additional funds. In 2002, the Globe reported that the company had received approximately $500 million in such contract changes, called change orders.

``It was like open feeding season for change orders," said Levy.

[StethyEntinic]

It is typical government contract BS.

There is a rule in private construction, get bids from a bunch of different qualified individuals with cost and familiarity with both the project and the owners being influential factors (one more public than the other, but still).

Any outrageously low or high bids, for essentially the same work, are thrown out and the other factors are weighted to try to get the most for their money.


I heard that with a lot of government contracts, certain laws were either made, or removed, that made it so that the cheapest bid won the project in an attempt to lower the budgets of many municipalities. This seemed to work only for the ones that enacted it, with cost overruns happening well after the start and possible repertory steps needed to be taken long after the people forgot who put in this "cost saving" measure.


The only cost saving I have seen work so far has been the completion bonus that some contracts have been awarded. If the project is completed up to spec AND ahead of schedule, the company stands to gain a substantial financial incentive. While these incentives may appear gross, you see what happens with the alternative.

I am crossing my fingers that something is figured out that will promote good work rather than getting ones foot in the door long enough to piss all over the peoples atrium.....

[Donlupedron]

Probe looks at possible problems with handling epoxy
By Scott Allen and Sean P. Murphy, Globe Staff | July 14, 2006

Investigators are focusing on the possibility that the failure of epoxy caused the ceiling collapse in the Interstate 90 connector tunnel Monday night.

Glue on bolts removed from the tunnel roof near the accident site was brittle and cracked, instead of having the consistency of smooth glass it should have had, according to a source briefed on the state investigation but not authorized to speak publicly. The decayed appearance may be a sign of premature aging.

Investigators are looking at problems Big Dig crews might have had in handling the epoxy, which requires a precise series of steps to get maximum holding power, according to the source.

The industrial-strength epoxy that was supposed to hold up the concrete ceiling is no ordinary glue. Used properly, it's actually stronger than concrete by some measures, and it's widely used in construction all over the world.

Typically, the epoxy comes in two cylinders, one containing resin and the other hardener, that must be mixed to create the glue on the spot. Workers installing the ceiling in the connector tunnel would have drilled holes into the concrete roof of the tunnel, squirted the epoxy ingredients inside, and then inserted a bolt. Once the epoxy had hardened and workers had tested it, they could suspend steel hangers from the bolt assembly, creating the frame that holds up the tunnel's drop ceiling.

In the past, ceiling bolts in the connector and in other Big Dig tunnels have failed safety tests because construction workers failed to mix the two epoxy ingredients correctly, didn't let it harden long enough, or failed to properly clean the surfaces being glued together, according to state reports.

In addition, moisture on the bolts or in drill holes could have weakened the epoxy, engineers said. The connector tunnel had water leaks in the roof in 2000, when the contractors were paid an additional $10,000 for cleanup, according to Big Dig documents. However, it is not clear whether the 2000 leaks were in the area of the accident.

``It was either a progressive decline in the strength of the epoxy or more stress was progressively put on the bolt fixture assembly than planned for," said Jeffrey C. Evans, head of the department of engineering at Bucknell University in Pennsylvania.

If manufactured and applied properly, industrial epoxies are strong enough to bear heavy loads for generations. A 1996 study by engineers at the University of Johannesburg in South Africa concluded that epoxy can hold a metal rod several times better than concrete. An official at Hilti USA of Oklahoma, a leading maker of industrial adhesives, said some adhesive anchors are designed to hold more than 100,000 pounds each, a far greater load than the 5,000- to 6,000-pound concrete panels in the connector ceiling.

The bolt-and-epoxy system for fastening the connector ceiling relied heavily on the strength of the glue because the bolt isn't screwed tightly into the concrete. The hole is deliberately larger than the bolt to allow room for the epoxy, which adheres to the concrete and the threads of the bolt.

The specifications for the kind of epoxy used in the tunnel ceiling would require a worker to use a masonry drill to leave a rough surface in the hole for better adherence, and the bolt would need to be free of grease. The worker would also need to clean out dust from the drill hole with a wire brush and high-powered air hose, acording to Paul J. Malinaric, a semi-retired physicist in Groton who worked for numerous industrial companies.

``It's a very exact protocol that has to be followed," he said.

In the past, crews constructing the drop ceiling in the nearby Ted Williams Tunnel sometimes fell short in following protocols, resulting in bolts that didn't hold strongly. In 1994, eight out of 50 bolts failed strength tests because of ``improper mixing of the epoxy," according to a 1998 report by the Massachusetts Inspector General.

Later in 1994, five out of 58 bolts in the Ted Williams Tunnel tested failed because crews didn't allow the epoxy to harden long enough, didn't use enough of the material, and didn't properly clean the drill holes.

As the ceiling was being installed in the connector tunnel, at least five bolts failed pull tests in 1999 to see if they were securely fastened, according to the attorney general's office. Investigators looking through construction logs this week found no indication the drill holes had been cleaned out by air hoses as required, and the source briefed on the state investigation said there is evidence workers improperly used water as a cleaner.

Gareth Cook of the Globe staff contributed to this report.