A state highway crew removed 117 loose panels from the walls of the Callahan Tunnel — each one bigger than a king-sized bed — late Sunday and early Monday, following an emergency inspection after a panel fell into the roadway late last week, the state’s top highway official said.
Three dozen workers pulled on every one of the 2,400 enamel-coated metal panels that line the roughly mile-long tunnel beneath Boston Harbor, after corrosion in unseen support brackets caused a panel to pop off Friday evening, said Frank DePaola, highway administrator for the Department of Transportation.
“We’re confident that the remaining wall panels are firmly secured, and we feel that no one should have any concerns about the safety of those panels going forward,” DePaola told reporters Monday, promising to retest each panel every three months. “We’ll physically grab ahold of and pull on each panel to make sure they stay firmly attached.”
Those panels, measuring about 4 feet by 9 feet and exceeding 100 pounds, are meant to reflect light to brighten the tunnel and are designed to be easier to clean than the raw concrete walls behind them. They are held in place by a matrix of galvanized-metal frames and stainless-steel bolts, with the frames bolted to the concrete and the panels hooked onto the frames, DePaola explained.
A sample of the freshly removed framework — believed to be only 20 years old — was displayed Monday, looking as corroded and fragile as an artifact hauled up from the Titanic.
Because of annual inspections of all tunnels prompted by a ceiling-tile collapse in a Big Dig section in 2006 that killed a Jamaica Plain grandmother, highway officials knew that some Callahan panels occasionally came loose because of corroded frames and fasteners. None had ever fallen, and highway workers had either removed or reinforced those panels, believing the problems to be isolated, DePaola said.
With all of the Callahan panels scheduled for replacement in a little over a year, officials had not considered the potential problem severe enough to pull on all the panels to test their integrity, DePaola acknowledged.
“The best answer I can give you is that there hadn’t been a large frequency of these panels coming loose,” DePaola said in an interview. “We never really imagined that they would — that enough [fasteners] would fail that they would fall off the wall.”
Officials could not precisely date the panels or say who installed them, but said they were already slated for replacement in 2014 in an estimated $10 million to $12 million project that will also include resurfacing the two lanes of the tunnel. The Callahan carries eastbound traffic from downtown Boston and Interstate 93 toward East Boston and Logan International Airport. It runs parallel to the older, westbound Sumner Tunnel.
Opened in 1961, the Callahan carries roughly 24,000 vehicles a day. It is named for Lieutenant William F. Callahan Jr., who was killed in World War II and whose father presided over the Massachusetts Turnpike Authority during tunnel construction; it opened on what would have been the lieutenant’s 41st birthday, with congressman Thomas P. “Tip” O’Neill Jr. as master of ceremonies.
When the panels were installed, the tunnel was still managed by the turnpike authority, which dissolved three years ago, as lawmakers merged multiple agencies to form the Department of Transportation.
DePaola has run the new department’s highway division since mid-2011, following upheaval over the speed and candor with which the state disclosed that a light fixture had fallen in the Big Dig’s Tip O’Neill Tunnel in February 2011, and that it was indicative of a wider problem with tunnel lights. The fallout included the resignation of the state’s interim highway administrator.
Controversy over the speed and candor with which the state revealed the extent of that problem ultimately cost the interim highway administrator and the state’s transportation secretary their jobs.
The state has inspected the Callahan at least once a year since 2006, DePaola said, when officials promised annual reviews not just of Big Dig tunnels but of all harbor tunnels following a ceiling-tile collapse in the connector that links the Ted Williams Tunnel with other sections of the Big Dig, killing Milena Del Valle.
Those recent inspections indicated that the Callahan wall panels needed replacement, because of corrosion due to moisture, possibly accelerated by interaction between dissimilar metals in the bolts and frames, DePaola said.
But deterioration after two decades is not considered premature, he said. Though bridges and tunnels are typically designed to last 50 to 75 years, some components are less durable.
“Similar to a house, you do the roof every 25 years, but you hope your house would last 100,” DePaola said.
The Callahan problem offers a window into the billions in infrastructure maintenance and replacement needs across the state’s highway and transit systems, and comes just weeks before Beacon Hill leaders are expected to debate solutions to a long-mounting transportation funding crisis.
But DePaola said more money would not necessarily have meant fixing the Callahan sooner, though better technology might have made officials more attuned to the problem. Because of the effects on traffic by working on multiple highways in and out of Boston at once, the Callahan was not due for repair until early 2014 because of recent or ongoing work on the Neponset River and Tobin bridges and the Massachusetts Turnpike’s Prudential tunnel. All but the Tobin will be finished by then, while the painting and rust-remediation work on the Tobin will be on hold for the winter, DePaola said.
The department is in the midst of building a database to monitor the condition of all highway, bridge, and tunnel infrastructure, to track needs and repair work, using a management tool known as Maximo, DePaola said.
Until now, inspections and repairs of bridges and some Big Dig elements have been tracked using primitive databases, but inspection results, maintenance contracts, and everything else exist only as isolated e-mail attachments, computer files, or paper documents, he said.