Crucial East Coast highway bridge closed

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WILMINGTON, Del. (AP) — Highway engineers say a crucial
bridge on the Eastern Seaboard’s interstate highway system could imperil
drivers if traffic is allowed back on it.
The bridge, near
Wilmington, Delaware, was closed Monday when its support pillars were
found to be tilting. The Interstate 495 bridge won’t reopen anytime
soon, highway officials said Tuesday, and the 90,000 vehicles that cross
it every day are being diverted onto the main north highway, I-95,
further overloading one of the most crowded arteries in America.
Engineers
say ground under the columns moved and caused the supports to tilt.
Officials said they believe the mile-long bridge over the Christina
River is not in any danger of collapsing under its own weight. But out
of concern for public safety, they do not want to allow traffic back on
it until they find out more about what caused the pillars to shift.
"We
never said that it was ready to fail. We were concerned about the tilt
because that was abnormal behavior for that structure," said Rob
McCleary, chief engineer for DelDOT.
In a worst-case scenario,
such as a crash that forced traffic to back up and stall in both
directions on the six-lane bridge, certain parts of it might not be able
to handle the weight load within acceptable safety standards, officials
said.
"If all the traffic was stopped and you were directing
maximum stress and load on that bridge, you could get overload of
certain members, … that could potentially lead to failure," state
Transportation Secretary Shailen Bhatt said in an interview Tuesday with
The Associated Press. "But you never want to overload."
Four
pairs of 50-foot-tall columns that are 5 feet in diameter were leaning,
with the top of one roughly two feet out of line with the bottom. They
are tilting by as much as 2.4 degrees, or 4 percent, from vertical. The
whole bridge, built in 1974, needs to be inspected, officials say.
The
closing forces more traffic onto I-95, which runs through downtown
Wilmington, and already is heavily clogged during the morning and
afternoon rush hours. McCleary said a system to shore up and brace the
bridge will have to be designed, a process that will take weeks, not
days, and there is no exact timetable for the important roadway to
reopen.
"It’s not going to be open anytime soon," Bhatt said.
The problem was discovered by crews working on an unrelated project.
Two
employees of private geoscience consulting company Duffield Associates
saw some cracking in the soils around a dirt pile dumped on the east
side of the bridge — the direction in which the columns are tilting.
They then looked at the leaning columns and contacted transportation
officials, said the firm’s chairman, Jeff Bross.
"They were significant cracks," Bross said.
Bhatt could not say whether the dirt pile was there legally but noted that part of it appears to be in
DelDOT’s right of way.
It’s the latest crisis involving the half-century-old interstate system.
An
AP analysis of more than 600,000 bridges last year showed that more
than 65,000 were classified as "structurally deficient" and more than
20,000 as "fracture critical." Of those, nearly 8,000 were both — a
combination of red flags that experts say indicate significant disrepair
and similar risk of collapse.
The now-closed Delaware bridge was
classified as "fracture critical." A bridge is deemed that when it
doesn’t have redundant protections and is at risk of collapse if a
single, vital component fails. Bridge collapses are not common, but some
of the more prominent ones in recent history took place on fracture
critical spans.
As for the detours and traffic, the transportation
department has sent out notices from Maine to Florida, telling people
the best routes to take to avoid the 11-mile closure.
Joe Erthal
heard about the problem Tuesday morning while heading to Maryland from
Philadelphia, where he lives. Driving home that afternoon, he got mixed
up while trying to bypass the closure and mistakenly ended up on I-495.
"I
guess we’re just going to have to find another way around ’til
everything’s fixed again," Erthal said while consulting a map app on his
cellphone for directions.

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