PennDOT is reshaping its bridge inspection system after two collapses in the past three years, and highway agency officials say they hope the changes will prevent similar problems.
The partial collapses of a bridge over I-70 in Washington County in 2005 and the Birmingham Bridge in February 2008 have led to the changes. These changes include retraining inspectors and rewriting criteria on how to identify potential problems.
Since the Birmingham Bridge collapse, PennDOT has been updating its Bridge Safety Inspection Manual and retraining inspectors about rocker bearings. A rocker bearing—a movable mechanism that allows the bridge to shift with temperature changes and traffic conditions—jammed, leading to the collapse.
"Based on lessons learned, we became more conservative about making judgments on the condition of the concrete box beams during inspections," PennDOT spokesman Rich Kirkpatrick said.
"PennDOT has, in draft, a procedure for evaluating the rocker bearings so that inspectors have detailed guidance as to what to look for, like how much movement and capacity they have in the bearings, and how to measure that based on time and temperature," PennDOT District 11 Executive Dan Cessna said. "It's a statewide policy change."
"There are better ways to inspect bridge structures," said bridge expert Kent Harries, an engineering professor at the University of Pittsburgh. "The problem is, it's a change in technology and a change in paradigm. There are bottlenecks and hurdles that have to be overcome."
The expense of developing and implementing better technology is a problem for the agency. In 2007, state lawmakers adopted Act 44, which would generate about $1 billion annually for road and bridge work, but the state’s network of nearly 40,000 miles of roads and more than 25,000 bridges requires more money than Act 44 can provide.
