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With Hurricane Irma barreling across the Caribbean and headed toward Florida, visitors must leave the Florida Keys now under a mandatory evacuation order. (Sept. 6)
AP

NAPLES, Fla. — Hurricane Irma’s record winds could bring destruction to Florida’s weakest infrastructure, toppling bridges and cutting off access to isolated areas across the state. 

Although Florida has one of the best inspection records in the country, thousands of bridges, some of them crucial arteries, still are considered vulnerable to a strong hurricane’s storm surge and winds. 

More than 12,000 bridges stretch across Florida, and at least 17% of them are designated as structurally deficient or functionally obsolete, two classifications the Federal Highway Administration uses to identify bridges in need of repair or replacement.

The more than 2,000 deficient bridges carry more than 32 million vehicles every day. They connect small inlet neighborhoods on both coasts, span across bays and line the Florida Keys.

► Aug. 30: Texas has 53,488 bridges. Here’s the toll Harvey is expected to take
► March 31: Atlanta bridge collapse shows how fire defeats concrete, steel

During past storms, bridge destruction has blocked evacuations and put people out of rescue’s reach for hours. 

Civil engineers say the vast majority of the maintenance issues with Florida’s bridges are minor. 

But even small problems, such as too shallow a clearance or a clogged drainage system, could leave a bridge exposed during this weekend’s hurricane, said Kathy Ruvarac at the American Society of Civil Engineers. 

► Feb. 15: Nearly 56,000 bridges across USA called structurally deficient
► February 2016: 58,000 U.S. bridges found to be ‘structurally deficient,’ study says

A deficient rating doesn’t mean a bridge is unsafe or dangerous. But inspectors factor concerns about structural integrity when classifying them as structurally deficient — more serious, but far less common — or functionally obsolete, both of which fall under the umbrella of deficient.

Deficient bridges stand throughout the likely path of Irma, including those that carry hundreds of thousands of motorists every day and others along main evacuation routes, according to the bridge data maintained by the Florida Department of Transportation. 

An analysis shows: 

• 1 in 4 bridges in Miami-Dade County are classified as deficient. The county’s oldest and lowest rated bridges, first built in 1927, dot the Venetian Causeway around Miami’s Biscayne Bay.

• More than 300 bridges in Florida now qualify for replacement with federal bridge money.

• 1 in 7 bridges in southern most Florida’s Monroe County — which is likely to be the first to feel the effects of Irma — are deficient. With 20,000 daily vehicles, the Keys’ Cow Key Channel Bridge is the busiest in the county in need of repair.

The historic Camino Real Bridge in Boca Raton, first built in 1939 and renovated in 2007, has one of Palm Spring County’s lowest inspection ratings and most vulnerable structures, with daily traffic of 14,000 and access to beachfront neighborhoods. 

Florida transportatoin officials were not immediately available for comment Wednesday. 

► November 2015: Huge pothole closes I-75 bridge lanes in Michigan
► July 2015: Collapsed California bridge earned ‘A’ rating in previous year

“We are all focused on getting ready for the hurricane,” a department spokeswoman said in an email. 

Several well-known bridges in south Florida are not considered vulnerable, including Long Key and Seven Mile bridges in the Keys, Judge Jolly Memorial Bridge over the Big Marco Pass, and the Cape Coral Parkway over the San Carlos Canal. 

Police Chief Paul Doucette of Bennington, Vt., looks at a collapsed bridge Aug. 28, 2011, on Vermont 9 in Woodford, Vt., after the remnants of Hurricane Irene dumped torrential rains on the state (Photo: Austen Danforth, Bennington (Vt.) Banner via AP)

Gov. Rick Scott suspended all tolls across the state Tuesday to encourage easier travel. The department also has begun coordinating with the Army Corps of Engineers, Water Management Districts, and FHA to brace for infrastructure damage, according to a readiness memo.  

At a press briefing Wednesday in Marathon, Scott highlighted bridge safety as a key concern going into the storm. 

“This has potential for significant storm surge. We didn’t have that in Andrew,” Scott said. “You’re worried about what’s going to happen to bridges. You’re worried about what’s going to happen to our roads. You’re worried about all these things.” 

At 300 miles wide and winds swirling up to 185 miles an hour Wednesday, Irma is expected to blanket the state with a force Floridians haven’t seen in decades. 

Forecasters have predicted storm surges to reach 20 feet, approaching the height of those in Hurricane Katrina, the Category 3 storm that devastated the Mississippi Delta area in 2005 and killed 1,800 people. 

Katrina destroyed dozens of bridges in Alabama, Louisiana and Mississippi. Researchers noticed that huge storm surges created pressure pockets beneath bridges, lifting and bending the support beams until they snapped. 

Katrina’s winds, which topped out at 125 mph, created surges 28 feet high before “submerging or overturning bridges,” researchers wrote in a 2007 forensic engineering study.

► July 2015: I-10 bridge collapse could lead to higher costs
► April 2015: 61,000 U.S. bridges ‘structurally deficient,’ analysis shows

Gilberto Mosqueda, an engineering professor at the University of Buffalo in New York and the study’s lead author, said a lesson learned from Katrina is that bridges “account for gravity. They’re not designed to resist an uplift force.” 

Long stretches of bridge spanning areas such as the Florida Keys and Tampa Bay may pose similar risks beneath Irma. 

Florida Highway Patrol Sergeant Steve Gaskins urged residents to evacuate sooner rather than later to avoid bottlenecks on bridges where wind gusts can be deadly. 

“If everyone leaves at the last minute, we have chaos and pandemonium on the roadways,” Gaskins said.

Follow Brent Murphy on Twitter: @BrettMMurphy

Bridges in harm’s way

Florida has more than 12,000 bridges. About 2,000 of them are functionally obsolete or structurally deficient, making them more vulnerable to damage or destruction from Hurricane Irma. Hover over each county to see bridge details.

 

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