COVINGTON, Ky. - A bridge that is both fracture critical and structurally deficient connects Covington and Cincinnati.
It's not the Brent Spence, but the Roebling Suspension Bridge.
The Brent Spence Bridge gets all the attention because a replacement structure is badly needed. It is classified as functionally obsolete, but not structurally deficient.
What do those terms mean?
Under Federal Highway Administration classifications , a structurally deficient bridge suffers from either poor design or physical decay that requires limits on the weight or spacing of vehicles allowed to travel on it. A functionally obsolete bridge is a span that is either too narrow or carries more traffic than it was designed to handle. A bridge can be classified as either structurally deficient or functionally obsolete, but not both.
Out of Ohio's nearly 14,000 bridges, 6,381 bridges are either structurally deficient or functionally obsolete, according to the 2011 National Bridge Inventory.
Kentucky has 4,257 deficient bridges, while Indiana has 3,939. In all, roughly one out of every four bridges in the Tri-State can be classified as either structurally deficient or functionally obsolete.
Such bridges can also be considered fracture critical.
A fracture critical bridge is a steel structure with no redundancy. The failure of a single piece of steel could cause the entire bridge to fail.
The I-35W bridge in Minneapolis was both fracture critical and structurally deficient. When it collapsed in 2007, 13 people were killed.
The Silver Bridge connecting Gallipolis, Ohio and Point Pleasant, West Virginia was also a fracture critical bridge. A small, unseen crack in a single steel eye bar caused the entire bridge to fall into the Ohio River in 1967. Because the failure occurred during rush hour when the bridge was packed with vehicles, 46 people were killed in the collapse.
"It's always in the back of your mind, you know, is this bridge safe?" said Cindy Cherry. She lost her mother and her sister in the Miamitown Bridge collapse in 1989.
The temporary span across the Great Miami River was not designed to handle the lateral forces created by flood waters. Helen Zorn, 52, and her daughter Terry Siemon, 27, were driving across the bridge when it suddenly gave way. Their bodies were pulled from the river days later.
"That it didn't have to happen is what's so troubling," Cherry said.
Ironically the temporary bridge was erected because the old Miamitown Bridge was deemed unsafe as both a fracture critical and structurally deficient structure. It was demolished once the temporary bridge was completed right next to it.
Saveourbridges.com analyzed data from the 2009 National Bridge Inventory to map the 7,980 bridges in the US that are both fracture critical and structurally deficient. Remember, that means the bridge is in poor condition and it could fall down if only one steel member fails.
That brings us back to the Roebling Suspension Bridge. It has stood majestically as the icon of Cincinnati since its twin towers were constructed in 1865, the year President Lincoln was assassinated. Experts say the Roebling Bridge should outlive us all, just as it has outlived its original builders.
But the suspension bridge is both fracture critical and structurally deficient. Annual inspections have uncovered cracks in the steel and other defects that have required temporary weight limits and repairs.
Recently the 11-ton vehicle limit was reduced to three tons while engineers inspected a crack near the Cincinnati tower . Over the decades, the bridge has been retrofitted, strengthened and maintained to preserve both the history and function of the Tri-State's most beloved span.
Other bridges considered both fracture critical and structurally deficient include the recently-closed 11th Street Bridge in Covington , and the Sixth Street Viaduct in Cincinnati.
Construction crews are nearly finished demolishing what's left of the most dangerous section of the Sixth Street Viaduct, and a replacement structure has already begun to take shape.
The I-Team used the map from saveourbridges.com to investigate about a dozen Tri-State bridges, expecting to find a series of dangerous spans in desperate need of replacement. Instead we found that since the time the data was collected in 2009, most of the worst bridges in our area have either been replaced, closed or are in the process of reconstruction.
View LePatner Bridge Map in a larger map
The Roebling Bridge was the one major exception, because replacing the historic span is out of the question. The commonwealth hires contractors to inspect the bridge every year .
The Ohio Department of Transportation inspects every bridge, every year. ODOT is currently building several replacement bridges in the southwest part of the state.
The new Jeremiah Morrow Bridge on I-71 is being constructed between the northbound and southbound lanes of the existing bridge.