University of Pittsburgh
February 7, 2008

Pitt Bridge Expert Kent Harries Available to Discuss Possible Severity And Circumstances of Birmingham Bridge Bearing Shift

Contact:  412-624-4147

PITTSBURGH—Bridge specialist Kent Harries, an assistant professor of civil and environmental engineering in the University of Pittsburgh's Swanson School of Engineering, is available to discuss the possible severity and circumstances of the rocker bearing shift that has led to the closure of the Birmingham Bridge.

Rocker bearings support the bridge deck and are designed to accommodate a degree of movement. Excessive movement resulting in a failure of these bearings can result from a number of factors. Until more is known about why the rocker bearing on the Birmingham Bridge shifted, it is difficult to determine whether the problem is isolated or the result of a larger, more serious problem, Harries said. A worse case scenario would include movement of the bridge's support columns, he said.

A simple inspection can most likely determine the cause of the shift, Harries said.

Harries added that although temperature changes could be a factor in the bearing's movement, as is currently thought, there are most likely additional contributing factors.

"These bearings are designed to accommodate temperature changes, and we haven't experienced the kind of extreme temperatures recently that alone would cause them to fail," Harries said. "There has to be another contributing factor. Unfortunately, we may never know what that is."

Harries commended PennDOT on its quick response to the problem. "In this case, the system worked," he said.

Harries can be reached at 412-624-9873 (office) or at kharries@pitt.edu, or by calling Morgan Kelly.

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