South Florida has problem bridges, website says
Aug 2, 2012
The following article was published in the Sun Sentinel on August 2, 2012:
South Florida Has Problem Bridges, Website Says
By Michael Turnbell
When drivers cross the Camino Real bridge over the Intracoastal Waterway in Boca Raton, few probably realize the 73-year-old span is in such poor condition that the failure of one major part could cause its collapse.
It is one of three such bridges in Palm Beach County, according to SaveOurBridges.com, a new bridge data website. The site was created by the author of a book on bridges who fears a catastrophe similar to one five years ago in Minneapolis, when the Interstate 35W bridge suddenly collapsed, killing 13 and injuring 145.
All three Palm Beach County bridges are on routes to the beach and are in various stages of being either replaced or repaired. Officials, however, stress that none are unsafe or in danger of collapsing and that each undergoes rigorous routine inspections, some as frequently as six months.
No bridges in Broward made the list. Six of the seven bridges listed inMiami-Dade County have been either repaired or replaced since 2009.
The Minnesota collapse resulted mainly from a design flaw that had gone undetected.
LePatner’s website lists bridges in the U.S. that are both “fracture critical” and “structurally deficient,” based on a 2009 database from the Federal Highway Administration.
“Fracture critical” is an engineering term meaning the bridge was designed in a way that lacks redundancies, so a failure of any number of structural elements would cause the entire bridge to collapse.
Bridges rated “structurally deficient” have problems with beams or pilings, erosion, or, if it’s a drawbridge, machinery. While they need repair or replacement, officials stress that doesn’t mean they are in danger of collapsing.
Every drawbridge over the Intracoastal in South Florida is fracture critical. Engineers say the term doesn’t mean they are unsafe.
“We still design fracture critical bridges today,” said John Danielsen, structures maintenance engineer for the Florida Department of Transportation. “The term tells the fabricator that more stringent testing requirements are necessary for those pieces of the bridge.”
The Camino Real bridge is slated for major rehabilitation next year. Palm Beach County is planning to spend more than $6 million to replace its pilings and repair the deck.
The span, built in 1939 over the Intracoastal Waterway next to the Boca Raton Resort & Club, had been scheduled for replacement until engineers found out it was eligible to be listed on the National Register of Historic Places.
The bridge’s deteriorating condition led the county to lower its maximum allowable weight from 36 tons to 30 tons. A $1.7 million minor renovation in 2007 did nothing to substantially improve the structure.
County officials are considering whether the bridge tender house on the south side of the span can be relocated to the north side to improve views for the bridge tender and still keep the historic integrity of the bridge.
The other problem bridges in Palm Beach County include the Flagler Memorial Bridge and the Southern Boulevard bridge, both in West Palm Beach and both targeted for replacement over the next several years.
In both cases, it’s the pilings that are driving their replacement, Danielsen said.
The state will begin construction of the new Flagler Memorial Bridge this summer. The startup was delayed for months over a dispute between the Florida Department of Transportation and the Palm Harbor Marina. The state is paying $6 million to the marina and the city of West Palm Beach to settle a dispute over potential damage to the marina and easements.
The $94.2 million span will be built directly south of the existing bridge. As soon as it opens in 2014, construction will begin on a new Southern Boulevard bridge.
In Miami-Dade County, repairs were completed to the Venetian Causeway, the Interstate 395 westbound bridge from Biscayne Boulevard to Northwest Third Avenue, the northbound I-95 bridge from Southwest Eighth to Northwest Eighth streets, the Northwest 17th Avenue bridge over the Miami River and the Northwest South River Drive bridge over the Tamiami Canal.
The U.S. 1 bridge over the C-111 Canal along the 18-mile stretch between Florida City and Key Largo has been replaced. Only the South Miami Avenue bridge over the Miami River awaits repairs.
The state has a much larger inventory of bridges classified either structurally deficient or functionally obsolete. The latter means the bridge needs to be widened or expanded to handle current traffic.
In Broward, there are 14 structurally deficient bridges and 96 functionally obsolete bridges. Palm Beach County has six structurally deficient bridges and 77 functionally obsolete bridges.
Florida bridges are inspected at least every two years. If they are found to be “structurally deficient,” inspections are made at least once a year, sometimes every six months.
In the wake of the Minneapolis bridge collapse, fracture critical components now must all be inspected “hands on” in the field. Before 2007, inspectors would look at design plans for the bridge and do calculations. “Now we have to go out and physically measure those pieces,” Danielsen said.
Next year, the Sunrise Boulevard bridge over the Middle River just west of the Galleria will be replaced. A temporary bridge will be built to carry traffic while the existing bridge is replaced. In 2014, the eastbound Broward Boulevard bridge over the North Fork of the New River just east of I-95 will be replaced.
View the original article here: http://www.sun-sentinel.com/news/palm-beach/fl-fracture-critical-bridges-20120802,0,4766992.story