Longfellow, other spans scrutinized
Bridge similar to design in Minneapolis
State officials revealed yesterday that the time-ravaged Longfellow Bridge is a steel arch truss bridge similar in design to the bridge that collapsed in Minneapolis Wednesday and are examining inspection reports for two dozen bridges, including the Longfellow.
The span, which carries tens of thousands of cars and Red Line commuters over the Charles River each day, is one of 588 bridges in Massachusetts that are considered structurally deficient under federal safety standards. The century-old bridge has undergone just one major overhaul, in 1959.
Officials also said they added the Whittier Bridge, which carries Interstate 95 across the Merrimack River in Amesbury and Newburyport, and the Eliot Bridge on the Charles River to the list of bridges they will review this weekend before beginning on-site inspections Monday.
The Longfellow is already slated for a major reconstruction project in 2010 -- several years later than initially planned -- that will cost up to $200 million. But the disaster in Minnesota focused new attention on structurally deficient bridges, particularly those of similar design. The Minneapolis bridge was also a steel arch deck truss bridge, though it was built with a single, 458-foot steel arch to avoid putting piers in the Mississippi River and impeding river navigation, according to the Federal Highway Administration.
Two days after the Minneapolis tragedy spurred states across the nation to examine their aging infrastructure, Massachusetts officials were still scrambling to assess which of the state's 5,000 bridges warranted further study. On Thursday, just hours after the collapse, state highway officials said there were 27 Bay State bridges of similar design. That number rose to 38 by Thursday night, but then yesterday declined to 24 -- a list that included all of the state's steel deck truss bridges and steel arch truss bridges, like the Longfellow.
"There was confusion as to whether or not this qualified as one of the bridges," John Lamontagne, state transportation spokesman, said yesterday of the Longfellow.
Of those 24, nine bridges -- including the Longfellow and the Amesbury spans -- have been deemed structurally deficient by federal standards, which does not necessarily mean they are unsafe or at risk of imminent collapse, but that they need to be monitored or repaired.
Investigators have not determined the cause of the collapse of the Interstate 35W bridge in Minneapolis, which killed at least five and injured 100. But officials in many states are scrutinizing their bridge inspection records, hoping to prevent a similar disaster.
Massachusetts officials said they will work through the weekend to scrutinize inspection reports for bridges with the same basic design as the Minneapolis span. As of yesterday, they had reviewed inspection records for 14 and found no cause for concern, said Thomas Broderick, director of highway safety for the Massachusetts Highway Department. By Monday, they intend to begin hands-on examinations of the nine structurally-deficient bridges and others, if deemed necessary after reviewing the inspection reports.
"These inspections are really a precaution. We don't know exactly what caused the collapse, and we don't know whether the design itself was a factor in the collapse of the bridge," said Luisa Paiewonsky, commissioner of the Massachusetts Highway Department.
The collapse occurred just a day after the Pioneer Institute think tank issued a report, chronicling the lack of funding for Massachusetts' infrastructure, which singled out the Longfellow as a symbol of the dangers of political neglect. On Thursday, the state did not include the Longfellow on its original list of bridges under scrutiny.
The Longfellow Bridge was last inspected in September, and undergoes annual inspections because of its condition.
But one only needs to glance at the structure to know it has seen better days.
Greenish-gray paint peeks through layers of dark-brown and orange rust covering the steel arches. The reinforcements look like the wreckage of an old ship, idle for years on the ocean floor. Some of the large bolts that lock the steel into the granite bases look like they are shrinking from rust. A few newly painted steel panels and beams stand out amid the corrosion.
"The bridges need work, there's no question," said Richard Regan, 60, of Arlington, who was walking near the Longfellow this week. "It's a serious problem and I don't know how we're going to fix it. . . . The only time we pay any mind to it is when something bad happens."
The Pioneer Institute report pointed to design problems with the bridge, built on 20,000 wooden pilings driven into the bed of the Charles River. Current engineering practice would call for those piles to be driven into bedrock to eliminate settling. Granite piers -- no longer used in modern bridges -- have been cracked due to water seepage and the cycle of freezing and thawing.
David Westerling, associate professor of civil engineering at Merrimack College who coauthored the report, characterized the bridge as safe. But, he asked, "when we have these minor structural pieces that are in poor condition, how long is it going to take before some of the major components are in poor condition? Probably not too much longer. We described it in the report like taking care of your car. . . . You've either got to repair it or run it into the ground."
With its trademark "salt and pepper shaker" towers, granite piers, and concrete deck, the Longfellow looks dramatically different than the Minneapolis interstate did. But it shares a similar steel arch design.
Westerling says it has a very sturdy base -- as long as the steel girders and posts that support loads are secure.
Those century-old steel elements have been subject to corrosion over the years and will be examined as part of the major state reconstruction of the bridge. In 2006, some of those elements received a score of 4 -- meaning poor -- on a scale of 1 to 9, according to the Pioneer report.
The bridge is owned by the state Department of Conservation and Recreation, but MassHighway has agreed to manage the reconstruction.
Because the bridge, which carries the Red Line, is such a major thoroughfare -- traversed by about 90,000 transit users, 40,000 motorists, and countless pedestrians and cyclists each day -- the state intends to keep the bridge open during reconstruction.
The work will focus on upgrading the structural capacity -- steel elements supporting the deck have deteriorated -- as well as modifying abutments for handicapped accessibility, adding lighting, and restoring ornate railings.
While considered structurally deficient, the Longfellow is not among the worst bridges in the state, according to federal data. It has a deficiency rating of about 51 percent, just short of the 50 percent threshold that would indicate it might need replacement.
Globe correspondent Claire Cummings contributed to this report. 