AP IMPACT: Many US Bridges Old, Risky and Rundown
WASHINGTON
September 15, 2013 (AP)
By JOAN LOWY
and MIKE BAKER Associated Press
Motorists
coming off the Frederick Douglass Memorial Bridge into Washington are treated
to a postcard-perfect view of the U.S. Capitol. The bridge itself, however, is
about as ugly as it gets: The steel underpinnings have thinned since the
structure was built in 1950, and the span is pocked with rust and crumbling
concrete.
Here is the structurally deficient Frederick Douglass bridge...you notice how nicely painted (corrosion prevention) this dangerous bridge is compared to the not structurally deficient Hinsdale NH route 119 bridge. Check out how nice those bridge piers look. You can click on the picture to make it bigger. This bridge looks almost new compared to the 1921 Hinsdale bridge.
District
of Columbia officials were so worried about a catastrophic failure that they
shored up the horizontal beams to prevent the bridge from falling into the
Anacostia River
And
safety concerns about the Douglass bridge, which is used by more than 70,000
vehicles daily, are far from unique.
An
Associated Press analysis of 607,380 bridges in the most recent federal
National Bridge Inventory showed that 65,605 were classified as
"structurally deficient" and 20,808 as "fracture critical."
Of those, 7,795 were both — a combination of red flags that experts say
indicate significant disrepair and similar risk of collapse.
So the Hinsdale bridge is "not" structurally deficient....not even on the red list.
This is where the huge truss arching over the top of the
deck gets attached to the concrete footing or foundation. The paint job or corrosion preventing
coating is disgusting on our bridge and it is indicative of disgraceful NHDOT
maintenance.
A
bridge is deemed fracture critical when it doesn't have redundant protections
and is at risk of collapse if a single, vital component fails. A bridge is
structurally deficient when it is in need of rehabilitation or replacement
because at least one major component of the span has advanced deterioration or
other problems that lead inspectors to deem its condition poor or worse.
Actually that roller bearing on this truss above is damaged and non functional...it is rust or corrosion frozen. This crumbling concrete holds up one of the four truss legs...the concrete foundation under all the legs are no better.
Engineers
say the bridges are safe. And despite the ominous sounding classifications,
officials say that even bridges that are structurally deficient or fracture
critical are not about to collapse.
The
AP zeroed in on the Douglass bridge and others that fit both criteria — structurally
deficient and fracture critical. Together, they carry more than 29 million
drivers a day, and many were built more than 60 years ago. Those bridges are
located in all 50 states, plus Puerto Rico and the District of Columbia, and
include the Brooklyn Bridge in New York, a bridge on the New Jersey highway
that leads to the Lincoln Tunnel, and the Main Avenue Bridge in Cleveland
The
number of bridges nationwide that are both structurally deficient and fracture
critical has been fairly constant for a number of years, experts say. But both
lists fluctuate frequently, especially at the state level, since repairs can
move a bridge out of the deficient categories while spans that grow more
dilapidated can be put on the lists. There are occasional data-entry errors.
There also is considerable lag time between when state transportation officials
report data to the federal government and when updates are made to the National
Bridge Inventory.
Many
fracture critical bridges were erected in the 1950s to 1970s during
construction of the interstate highway system because they were relatively
cheap and easy to build. Now they have exceeded their designed life expectancy
but are still carrying traffic — often more cars and trucks than they were
originally expected to handle. The Interstate 5 bridge in Washington state that
collapsed in May was fracture critical.
Cities
and states would like to replace the aging and vulnerable bridges, but few have
the money; nationally, it is a multibillion-dollar problem. As a result,
highway engineers are juggling repairs and retrofits in an effort to stay ahead
of the deterioration.
There
are thousands of inspectors across the country "in the field every day to
determine the safety of the nation's bridges," Victor Mendez, head of the
Federal Highway Administration, said in a statement. "If a bridge is found
to be unsafe, immediate action is taken."
At
the same time, all that is required to cause a fracture critical bridge to
collapse is a single unanticipated event that damages a critical portion of the
structure.
"It's
kind of like trying to predict where an earthquake is going to hit or where a
tornado is going to touch down," said Kelley Rehm, bridges program manager
for the American Association of State Highway and Transportation Officials.
Signs
of age are clear. The Douglass bridge, also known as the South Capitol Street
Bridge, was designed to last 50 years. It's now 13 years past that. The
district's transportation department has inserted so-called catcher beams
underneath the bridge's main horizontal beams to keep the bridge from falling
into the river, should a main component fail.
The so-called catcher beams...
Why doesn't the Hinsdale bridge have catcher beams...
Alesia
Tisdall, who drove over the bridge every day for 15 years but now crosses it
only occasionally, said she found its "bounce" unnerving.
"You'd
look at the person sitting next to you like, 'Did you feel that bounce?' And
they'd be looking back at you like they were thinking the same thing,"
said Tisdall, a computer systems specialist at the Justice Department.
Peter
Vanderzee, CEO of Lifespan Technologies of Alpharetta, Ga., which uses special
sensors to monitor bridges for stress, said steel fatigue is a problem in the
older bridges.
"Bridges
aren't built to last forever," he said. He compared steel bridges to a
paper clip that's opened and bent back and forth until it breaks.
"That's
a fatigue failure," he said. "In a bridge system, it may take
millions of cycles before it breaks. But many of these bridges have seen
millions of cycles of loading and unloading."
That
fatigue is evident in a steel truss bridge over Interstate 5 in Washington
state — south of the similar steel truss that collapsed in May. The span that
carries northbound drivers over the east fork of the Lewis River was built in
1936.
Because
of age, corrosion and metal fatigue caused by vibration, the state has
implemented weight restrictions on the bridge. Washington state Department of
Transportation spokeswoman Heidi Sause said the bridge wasn't built for the
kind of wear — bigger loads and more traffic — that is now common.
"This
is a bridge that we pay close attention to and we monitor very carefully,"
Sause said.
The
biggest difference between the bridge over the Lewis River and the one over the
Skagit River that collapsed May 23 is that the span still standing has actually
been listed in worse condition. State officials hope to replace it in the next
10 to 15 years.
While
the Skagit span was not structurally deficient, the I-35W bridge that collapsed
in Minneapolis in 2007 had received that designation. The bridge fell during
rush hour, killing 13 people and injuring more than 100. The National
Transportation Safety Board concluded that the cause of the collapse was an
error by the bridge's designers, not the deficiencies found by inspectors. A
gusset plate, a fracture critical component of the bridge, was too thin.
Many
of the bridges included in the AP review have sufficiency ratings — a score
designed to gauge the importance of replacing the span — that are much lower
than the Skagit bridge. A bridge with a score less than 50 on a 100-point scale
can be eligible for federal funds to help replace the span. More than 400
bridges that are fracture critical and structurally deficient have a score of
less than 10, according to the latest federal inventory.
The
Brooklyn Bridge is among the worst.
There
are wide gaps between states in historical bridge construction and their
ongoing maintenance. While the numbers at the state level are in flux, Iowa,
Nebraska, Missouri and Pennsylvania have all been listed recently in the
national inventory as having more than 600 bridges both structurally deficient
and fracture critical.
Pennsylvania
has whittled down its backlog of structurally deficient bridges but still has
many more to go, with an estimated 300 bridges in position to move onto the
structurally deficient list every year if no maintenance is done. Barry Schoch,
the state transportation secretary, said in an interview that officials would
like to add redundancy to fracture critical bridges when they can, particularly
if a bridge is also structurally deficient.
"Those
are high on the priority list," Schoch said.
After
the 1983 collapse of the I-95 bridge over the Mianus River in Connecticut, the
focus turned to a fracture critical bridge style known as pin-and-hanger
assembly.
Pennsylvania
worked over the following years to add catcher beams to its pin-and-hanger
spans. That's the case now on the George Wade Bridge that carries I-81 traffic
across the Susquehanna River. More recently, crews have also been trying to
move the bridge off the structurally deficient list after finding significant
cracks in the piers.
Officials
say northeastern states face particular challenges because the infrastructure
there is older and the weather is more grueling, with dramatic and frequent
freeze-thaw cycles that can put stress on roads and bridges.
Many
Pennsylvania lawmakers have long sought to boost transportation funding, in
part to address crumbling bridges. But this year's proposals, including Gov.
Tom Corbett's $1.8 billion plan, stalled amid fights over details.
That's
a common issue among infrastructure managers in other states, who say they
don't have the money to replace all the bridges that need work. Instead, they
continue to do patch fixes and temporary improvements.
Washington's
Douglass bridge has been rehabilitated twice. The catcher beams were added
because the pin-and-hanger expansion joints that hold the bridge's main girders
in place had deteriorated to the point "we were concerned that we could
have a failure, and that the failure could be catastrophic," said Ronaldo
Nicholson, the chief bridge engineer for the area.
"If
the joint fails, then the beam doesn't have anything to carry itself because
there are only two beams. Therefore the bridge fails, which is why we call it
fracture critical," Nicholson said.
The
bridge has a sufficiency rating of 60, an increase from the 49 rating in 2008
before some repair work was done. It remains structurally deficient because
inspectors deemed the superstructure in poor condition due to "advanced
structural steel section loss with holes and overhang bracket connection
deficiencies," according to an inspection report from earlier this year.
A
new bridge would cost about $450 million if it was required to be able to open
so large ships can travel the Anacostia, an infrequent occurrence, Nicholson
said. If not, the cost could be as low as $300 million, he said.
Nicholson
emphasized that if city officials feel the bridge is unsafe, they'll prohibit
trucks from crossing or close the span entirely. Inspections have been stepped
up to every six months instead of the usual two-year intervals for most
bridges. In the meantime, officials are trying to stretch the bridge's life for
another five years — the time they estimate it will take to build a
replacement.
Congressional
interest in fixing bridges rose after the 2007 collapse in Minneapolis, but
efforts to add billions of extra federal dollars specifically for repair and
replacement of deficient and obsolete bridges foundered. A sweeping
transportation law enacted last year eliminated a dedicated bridge fund that
had been around for more than three decades. State transportation officials had
complained the fund's requirements were too restrictive. Now, bridge repairs or
replacements must compete with other types of highway projects for federal aid.
The
new law requires states to beef up bridge inspection standards and
qualifications for bridge inspectors. However, federal regulators are still
drafting the new standards.
"Do
we have the funding to replace 18,000 fracture critical bridges right
now?" Rehm asked. "No. Would we like to? Of course."
———
Baker
reported from Seattle. Interactive Newsroom Technology Editor Troy Thibodeaux
in New Orleans contributed data analysis.
———
The
AP National Investigative Team can be reached at investigate@ap.org
