WASHINGTON - In a strategic plan laid out in 1998, the Federal Highway Administration set a 10-year goal of shoring up the nation's nearly 600,000 federally funded bridges so that fewer than 20 percent would be classified as deficient.
But Wednesday's stunning rush-hour collapse of a 600-foot bridge span along Interstate Highway 35W in Minneapolis served as a reminder that the vision fell short: More than one in four of those bridges still are rated "structurally deficient" or "functionally obsolete."
The disaster triggered political finger-pointing over the need for greater infrastructure spending and prompted Transportation Secretary Mary Peters to send an advisory urging state officials to immediately inspect roughly 700 similarly designed truss bridges.
"We have a national bridge problem," said Rep. James Oberstar, D-Minn., the chairman of the House Transportation and Infrastructure Committee. He said that 79,523 federally funded bridges are rated "functionally obsolete," meaning they need replacing.
The tragedy also heightened attention on bridge-inspection standards, which already had drawn scrutiny. Last year, a Transportation Department audit of 43 bridges in Massachusetts, New York and Texas found that bridge inspectors routinely miscalculated the load capacity of structurally deficient bridges, posting weight limits that allowed vehicles exceeding the safety threshold or failing to post limits at all.
The I-35W bridge over the Mississippi River in Minneapolis has a non-redundant truss design, meaning that the failure of any component of its steel superstructure or the buckling of one of its four concrete piers could cause a collapse.
The 40-year-old bridge was erected shortly before the Silver Bridge over the Ohio River, another non-redundant truss bridge, collapsed due to the failure of a single piece of hardware around Christmas in 1967, killing 46 people. That disaster led to changes in the design of truss bridges, although investigators have yet to determine whether the two collapses had similar causes.
Peters responded to Wednesday's collapse by asking Transportation Department Inspector General Calvin Scovel to review the agency's bridge-inspection program, to ensure that states are "looking at the right things in the bridges," department spokesman Brian Turmail said.
"What troubles the secretary is that the kind of indicators that the bridge-inspection program was designed to flag didn't get flagged," he said. "If you look at the paperwork, there were no indicators that the bridge needed to have traffic reductions in place, as some bridges do. There were no indicators that the bridge needed to be shut."
Democrats in Congress suggested that the disaster signals a widespread problem rooted in national neglect.
"This really should be a wake-up call for America," declared Senate Majority Leader Harry Reid, D-Nev. "We have an infrastructure that is deteriorated and deteriorating - bridges, dams, highways, water systems, sewer systems - and since Sept. 11, we simply have taken our eye off the ball."
Shankar Nair, a nationally known structural engineer who specializes in bridge design, agreed in principle that the nation's bridges badly need to repair problems such as corroding steel or cracked concrete, but said in an interview that few, if any, are in danger of collapse.
"I think our bridges are in terrible shape, and I think we need to spend a bundle of money to bring them up to snuff," said Nair, who's based in Chicago. "But the danger of an actual collapse that causes fatalities is still pretty small. I don't worry (when) driving that the bridge I'm on is going to fall down. And that is especially true of the bigger bridges."
Nair said that even non-redundant truss bridges have performed well and shouldn't provoke major concerns "with modern steels and modern design techniques."
"Highway departments and engineers are conservative people," he said. "We're nervous people. When we say that a bridge is unsafe, it doesn't mean it's going to fall down. It means that the margin (of safety) is not as good as it should be."
Oberstar said he'll press next year to increase the nation's annual funding for bridge construction and repair from $2 billion to $3 billion. He blamed President Bush for slashing Congress' highway spending bill last year by nearly $90 billion.
White House press secretary Tony Snow called the Minnesota bridge collapse a "unique disaster," noting that the state has a rigorous bridge inspection program and that bridge collapses occur on rare occasions. He said that politicians should reserve judgment until experts have determined the cause.
California Democratic Sen. Barbara Boxer, the chair of the Senate Committee on Environment and Public Works, vowed to hold hearings after the August recess "on the condition of our national infrastructure and how we can prevent tragedies like this from happening in the future."
"Many Americans are asking, 'Could it happen here?"' said Sen. Patty Murray, D-Wash., the chair of a Senate Appropriations subcommittee and shepherd of a $104 billion transportation and housing spending bill that Bush has threatened to veto.
"He says it spends too much on our nation's transportation infrastructure. I don't see how he can keep making that argument as Americans see the images of a bridge that is now a tangle of steel and concrete languishing in the middle of the Mississippi River."
Bridge Component Ratings
The National Bridge Inventory (NBI) contains ratings on the conditions of three major bridge components: deck, superstructure, and substructure:
8: Very Good
7: Good. No problems noted.
6: Satisfactory. Some minor problems.
5: Fair. All primary structural elements are sound but may have minor section loss, cracking, spalling, or scour.
4: Poor. Advanced section loss, deterioration, spalling or scour.
3: Serious. Loss of section, deterioration, spalling or scour have seriously affected the primary structural components. Local failures are possible. Fatigue cracks in steel or shear cracks in concrete may be present.
2: Critical. Advanced deterioration of primary structural elements. Fatigue cracks in steel or shear cracks in concrete may be present or scour may be removed substructure support. Unless closely monitored, it might be necessary to close the bridge until corrective action is taken.
1: Imminent Failure. Major deterioration or section loss present in critical structural components, or obvious loss present in critical structural components, or obvious vertical or horizontal movement affecting structural stability. Bridge is closed to traffic, but corrective action may put back in light service.
0: Failed/Out of Service; beyond corrective action.
SOURCE: U.S. Department of Transportation/Federal Highway Administration