A long line of lessons on bridge safety

The St. Georges Bridge over the C&D Canal is one of several with "fracture-critical" design features that could lead to a complete collapse. The Army Corps of Engineers has recommended the bridge be removed. (Buy photo) The News Journal/JENNIFER CORBETT

The state and federal governments have fought over the St. Georges Bridge over the C&D Canal for years. The state says it can be properly maintained, but the Army Corps of Engineers wants to close it down.(Buy photo) The News Journal JENNIFER CORBETT

Workers install instruments under the I-95 bridge over the Brandywine in 2003, when a birdwatcher spotted a large crack on its underside. News Journal file/ROBERT CRAIG

Ed Bried of Wilmington spotted a 7-foot crack on the Brandywine Creek Bridge in 2003.

Sometimes even the best managed bridges take people, and engineers, to places they'd rather avoid.

Witness the I-95 Brandywine Creek Bridge, a heavily used span that twice in 17 years developed dangerous cracks that were first spotted by pedestrians on the ground, rather than government inspectors.

Although neither discovery turned into the kind of tragedy now playing out around the collapsed I-35W span in Minneapolis, experts say Delaware's sometimes bumpy experience with bridges is typical for much of the nation.

For years, the public's vast and aging highway investments have produced shocks and surprises, from cracking lanes and closed highways to broken or load-restricted bridges.

"We have to recognize that assuring absolute safety is not achievable with finite resources," said Bilal M. Ayyub, professor and director at the Center for Technology and Systems Management at the University of Maryland. "Always, in any engineered or built-up system, there is some risk, although it's calculated and very small."

Wilmington resident Michael J. Paul had a glimpse of that very small risk in 1986, when he spotted a cracked girder in the I-95 bridge while jogging through Brandywine Park. Department of Transportation officials said there was no danger, but inspections and repairs crippled traffic on the busy highway for weeks.

"I think it's fair to say that would have been a bit of a surprise to DelDOT," recalled Paul, who now works as an engineer for Duffield Associates. "They did a very thorough inspection afterward. I think that particular condition was an anomaly."

Lightning struck again 17 years later, however, when birdwatcher Ed Bried of Wilmington spotted a 7-foot crack on the northbound side of the same bridge. The larger crack, traced to strains that followed construction-related shifts in traffic lanes, produced even larger travel disruptions and costly repairs, but no disaster.

Costly lessons

Delaware's highway program now rates among the best for bridge maintenance, and relies both on state employee experts and contractors to inspect its more than 1,400 structures. But the past 20 years have seen a series of emergency bridge closings, long, forced detours for buses and emergency vehicles and extended speed and truck restrictions.

At one point in 1991, highway officials resorted to a "Weak Bridge Ahead" warning to motorists along U.S. 13 north of Odessa after inspectors found dangerous and unexpected deterioration at a busy crossing at Drawyers Creek. Continuing problems there will cost taxpayers more than $10 million in coming years.

Victor Singer, a retired engineer who spent much of his career studying and working with aerospace metals, said the 2003 cracking episode on the Brandywine Creek Bridge exposed deep cracks in the nation's overall inspection program.

"The interstate bridge over the Brandywine broke in a situation where there was not a heavy load. If it had been heavily loaded and a little bit weaker, it would have come down," said Singer. "It was under repair at the time for something other than what caused the thing to break. That's a cause for substantial public interest."

Singer said inspections now fail to account for new understandings about metal strength and fatigue. He also pointed out that modern standards would prohibit use of the kind of steel used to build the Brandywine span.

Harry "Tripp" Shenton, an associate professor with the University of Delaware's Center for Innovative Bridge Engineering, said that engineers are constantly making discoveries about the strength and weaknesses of bridge-building materials and techniques. Some lessons come harder than others.

"They're not going to know for a long time what happened in Minneapolis," Shenton said. "It's an exclamation point. A reminder that we have a deteriorating infrastructure and that federal funds need to be allocated to maintain and replace and rehabilitate it, which the profession has been calling for for some time now."

Indian River bridge top concern

DelDOT's current top overall safety concern is the Del. 1 bridge over the Indian River Inlet in Sussex County. That span, which carries up to 28,000 vehicles daily during peak summer days, has the same "structurally deficient" rating as the Minneapolis Bridge, although federal officials rate it as meeting "minimum tolerable limits" to stay in service. Chief concerns include severe erosion around the bridge foundations in the fast-moving inlet and structural deterioration.

Traffic and planning officials say the inlet crossing is crucial to emergency service evacuation plans. A shutdown would add as much as 45 minutes to a trip between southern areas and Beebe Medical Center, and jam up remaining evacuation routes in the event of a storm or other natural disaster.

Only one DelDOT-maintained bridge has basic support features closely resembling the Minneapolis bridge: the Augustine Cut-off crossing of the Brandywine. State officials had that structure rebuilt, to higher standards, in the early 1990s in response to reforms that followed a bridge collapse in West Virginia.

The Army Corps of Engineers reported Friday that portions of the Summit Bridge on Del. 896 and Reedy Point Bridge on Del. 9 also rely on the same steel deck-and-truss design found at Minneapolis. All three corps-owned bridges over the Chesapeake & Delaware Canal, including the once-heavily used St. Georges Bridge, also have "fracture-critical" design features that, if broken, could lead to a complete collapse.

Delaware and the corps have sparred for years over upkeep of the St. Georges crossing, which operated with truck weight and speed restrictions for years. Delaware officials want the bridge to remain in service and properly maintained, but the Army Corps of Engineers has recommended its removal.

DelDOT spokesman Darrel Cole said state engineers began a review of the Augustine bridge on Friday, even before the Federal Highway Administration formally asked the state to review its share of the 749 steel deck-and-truss bridges now in use.

Cameron Chasten, a structural engineer with the Army Corps of Engineers' Philadelphia District, said a similar review was under way for that agency's truss bridges, although all have completed recent required inspections.

Cole said DelDOT also is examining the 20 state bridges known to have design features that, if broken, could lead to a complete collapse. That list includes the I-495 bridge over the Christina River, according to the Federal Highway Administration, and the I-95 bridge over Norfolk Southern Railroad tracks south of Wilmington. "We're going to look at the files again, a little more closely, to see if there's anything we can do," Cole said.

'A wake-up call'

FHWA reports from 2006 list 35 Delaware bridges that rate as "structurally deficient," the same classification given to the Minneapolis bridge. DelDOT already has plans for repairs or replacements to all of the most serious problems, but has had to cut its overall budget in recent years.

"It wouldn't surprise us if we learned that we might need to invest more than we anticipated to shore up some of our bridges," said Catherine L. Rossi, AAA Mid-Atlantic's manager of public and government affairs. "Certainly we're going to have to evaluate the risk. This is a wake-up call for all of us -- not only transportation officials and those who are actually looking at structures, but also policymakers and us as taxpayers."

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Posted by: CAPTJOHN- Sun Aug 05, 2007 9:04 am

All bridge inspections should be available online for public viewing.

Posted by: CAPTJOHN- Sun Aug 05, 2007 9:01 am

All bridges are safe until they fall down!

Posted by: willie- Sun Aug 05, 2007 8:50 am

["We're going to look at the files again, a little more closely, to see if there's anything we can do," Cole said.]

Typical red tape response!
We will look at the files?

How about they go look at the bridges!

Posted by: New Delaware- Sun Aug 05, 2007 8:45 am

ACE, get a clue. You WILL forever maintain all of the current bridges, or their replacements. If not, fill in the canal and get lost. There will be no be argument or negotiation. It's more likely there will be one less star on the flag (first in, first out!!) than you will ever escape your obligations. You are Delaware's "B" now, so bend over and act like it.

In fact, I'd start thinking about the new Rt 9 and 896 bridges now. Because you WILL be building them.

Posted by: Protack for Governor- Sun Aug 05, 2007 8:36 am

Fixing the bridges is not a nice to do item it is a must do item.

Accidents and mishaps are always a chain of events that could be stopped with correct and timely action.

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