From The Observer News
Are Our Bridges Safe?
By Mitch Traphagen email@example.com
Aug 9, 2007, 23:14
TAMPA – On a hot Wednesday afternoon, hundreds of people sat in rush hour traffic just outside downtown Minneapolis as they did every other afternoon. People chatted on cell phones, fiddled with iPods or radio stations, wondered what was for dinner or how the Twins baseball team would fare in a game that would soon begin. Traffic on the eight-lane bridge was bumper to bumper – nothing unusual but also made worse because of bridge construction that reduced the lanes to two in each direction. It was just an ordinary day in rush hour until everything went crashing down.
|One of the signature bridges in the state of Florida, the Sunshine Skyway Bridge was also the scene of a bridge tragedy in 1980 during which 35 people died after a freighter struck the bridge in bad weather. The bridge was subsequently rebuilt with increased protection against a similar threat. In 2004, significant corrosion problems were resolved by the Florida Department of Transportation. Mitch Traphagen Photo|
Despite being rated as structurally deficient, it is likely that no one expected the I-35W bridge over the Mississippi River would suddenly collapse. Certainly no one driving on the bridge expected that. Last May while traveling for a series of stories, I drove over that bridge with no thoughts of imminent danger. Had their been signs warning drivers that the bridge was deficient, that it rated only a four out of ten on a scale of structural integrity, many drivers probably would have simply driven past – the freeway is a major artery into the city, after all.
The bridge was built in 1967 and appeared on the problem radar as early as 1996 and was considered deficient two years ago. Everyone involved in decision-making knew the bridge would have to someday be replaced but someday was continually pushed back for another day. On Aug. 1, that day arrived as a tragic event.
In the end, with more than 100 people injured and an estimated 13 dead, attention is now being focused on the aging infrastructure of the nation’s highways and bridges. The warning bells, some of which, like those for the bridge in Minneapolis, had been ringing for years but now people are starting to listen. No one wants another tragedy.
On August 2, U.S. Secretary of Transportation Mary E. Peters called on each state to immediately inspect each of the 756 bridges that are similar in construction to the I-35W Bridge. That list included only one in Florida, the Pollywog Point Bridge near Labelle, a community between Ft. Myers and Lake Okeechobee.
On August 3, Hillsborough County issued a press release stating a bridge near Memorial Highway over Double Branch Creek was closing immediately until Sept. 3 due to structural issues. The bridge averaged less than 600 vehicles per day. Officials state the timing of the closure was coincidental to the Minneapolis collapse. On that bridge, pieces of concrete had fallen into the water exposing steel reinforcing beams.
While the sudden focus on potential problems is welcome by many, the task is daunting. In Hillsborough County, 78 bridges are considered structurally obsolete and five bridges are considered structurally deficient. Structurally obsolete means that a bridge is of older design that is not technically unsafe but cannot handle current traffic volume and vehicle weight. A structurally deficient bridge is restricted due to deteriorated components and, while not necessarily unsafe, should be restricted for speed and weight. The Double Branch Creek Bridge, now closed, was one of those considered deficient. Nationwide, there are nearly 600,000 bridges with more than 20 percent thought to have problems.
There are literally dozens of bridges in South Hillsborough alone ranging from small spans crossing creeks in residential neighborhoods to larger bridges such as those which traverse the Alafia River on U.S. 41 and on I-75. No bridge in South County is considered deficient, although a number are considered obsolete, including the U.S. 41 bridges over the Alafia.
In 2001, repairs were completed on the I-75 Alafia River Bridge. According to FDOT, deteriorated timbers on the fender system were repaired as well as improvements made to the riding surface. Part of the project goals included increasing the lifespan of the bridge and reducing the chance of unplanned, emergency repairs.
Around the Tampa Bay area, The Sunshine Skyway Bridge with the world’s longest cable stayed span was opened in 1987 after a freighter accident destroyed the southbound span of the original bridge that had been built in 1954. In that accident, which occurred on May 9, 1980, 35 people were killed as six cars and a Greyhound bus plunged into Tampa Bay at the collapse. Recently, corrosion problems had been a cause for concern on the current bridge, however the superstructure had been reinforced in 2004. FDOT is currently repainting the cables and retaining walls as well as updating the lighting.
The Howard Frankland Bridge, connecting Tampa to St. Petersburg, was originally built in 1959. A new span, the southbound lanes, opened in 1990 and the original bridge was reconstructed and opened as the northbound lanes in 1992.
The Gandy Bridge, originally opened in 1924, has been replaced and updated several times over the years. The westbound span was built in 1996; the eastbound span was built in 1976.
Are the nation’s bridges safe? Engineers began voicing concerns about bridges in the early 1980s – less than 30 years after construction on the Interstate Highway system began. But just as no one expected the I-35W Bridge to collapse, no one is able to give a definitive answer to that question. On one hand, the answer is clearly that some are not. The data does suggest, however, that the state of Florida and Hillsborough County have been reasonably proactive in taking steps to ensure the area’s bridges are safe. Florida does, after all, have it’s own experience with such tragedy. The bridge management program of Hillsborough County Public Works has committed to the biannual inspection and monitoring of all county bridges.
But as the shock and mourning of the tragedy in Minneapolis gives way to anger, it is also reasonable to conclude that a number of bridges will be, perhaps must be, safer in the future. Hopefully that will occur before another unexpected tragedy strikes more innocent people on an otherwise ordinary day.
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