While yesterday's bridge collapse in Minneapolis underscored the importance of regularly inspecting and repairing bridges, local officials previously have had that point driven home in dramatic fashion.

The most recent case was in 2005, when a section of bridge over Interstate 70 in Washington County collapsed.

"I feel comfortable that we have a safe transportation system, but we have to keep addressing our backlog of structurally deficient bridges," Pennsylvania Transportation Secretary Allen Biehler said last night. "We have 5,900 of them considered in that condition."

Mr. Biehler was watching live coverage on CNN of the tragedy in Minneapolis but said pictures and information were too sketchy for him to draw even a preliminary conclusion as to a possible cause.

However, when he called his bridge expert, Scott Christie, Mr. Christie speculated that construction involving nearby pile driving -- pounding huge steel I-beams into the ground -- as part of a bridge widening project might have disturbed the foundation and produced an "instant weakness."

PennDOT's long-standing concern about the condition of its bridges sounded loud and clear in December 2005, when a box-beam bridge over I-70 crumbled, leaving five people injured.

The incident triggered an investigation into other bridges of similar age and design throughout the state. Three were closed and razed in Washington County alone; two have been replaced, including the North Main Street Bridge at the South Strabane-Washington, Pa., line.

In the aftermath, PennDOT adopted a more rigorous inspection program that extended to other concrete and steel bridges. Dozens of other types have been closed or weight-restricted as well as the box-beam bridges, including some smaller concrete bridges called T-beam bridges built more than 60 years ago.

"We reacted in a very, very forceful way and on a broad scale," Mr. Biehler said. "People don't generally think too much about bridges until something like this [Minneapolis bridge collapse] occurs."

The Federal Highway Administration requires bridges 20 feet or longer to be inspected every two years. PennDOT inspects all bridges 8 feet or longer -- often every year if severe problems are suspected.

"Only when we did a forensic analysis [after the I-70 bridge incident] did we understand that things were going on inside beams that we couldn't know from inspecting them from the outside," Mr. Biehler said. "So we adopted more conservative standards. Our goal has been to err on the side of safety, even if it means closing a big bridge. We won't hesitate to do that if we feel it's necessary."

PennDOT has ramped up spending on bridge repairs and rehabilitation from $260 million in 2003 to $558 million last year. With increased state transportation funding that was recently approved, "significantly more money will be spent on bridges," Mr. Biehler said. "To this point, we've only been treading water."

Jim Struzzi, spokesman for PennDOT District 11, which includes Allegheny County, said the Washington County incident resulted in a "concerted effort" to keep the region's bridges in better condition and to inspect them more thoroughly.

"We spend literally hundreds of thousands of dollars each year on bridge maintenance," he said.

"This gets to the heart of the issue that the governor is fighting for right now," he said, referring to Gov. Ed Rendell's efforts to secure long-term funding for highway and bridge repairs.

Mr. Struzzi said last night that it was too soon to tell whether the Minneapolis collapse would prompt any special reaction on the part of local officials.

He said officials likely would review engineering information on the failed span to see if any comparisons can be drawn to bridges here.

In 2003, nearly three years after an interstate highway bridge in Milwaukee sagged and nearly collapsed into a river, Pennsylvania ordered remedial work on the welded plates fastening the steel beams of a dozen bridges in Allegheny County and two in Beaver County.

After it was determined that plates on the Milwaukee bridge fractured suddenly and caused a chain reaction of cracks in the superstructure, repairs were ordered to bridges with the same type of welded plates here.

That marked the third time for weld repairs on the massive Interstate 79 bridge between Robinson and Glenfield, a 3,700-foot steel arch bridge over the main channel of the Ohio River and a shorter box-beam bridge over Neville Island and the smaller river channel.

A catastrophe involving that bridge was averted in 1977, just months after the span opened, when a riverboat captain noticed a crack in a steel girder. PennDOT closed the bridge for three months while the crack was repaired.

Hairline cracks that started showing up in other pieces of steel necessitated $1.8 million of repairs and preventive work to the I-79 spans during the summer of 1999.