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Unlike Maryland, Delaware has made upgraded bridge pier protection a reality

Protective dolphins are being constructed around the support piers of the Delaware Memorial Bridge. The 26-month, $95 million project began in 2023 and when completed in 2025, will consist of eight 80-foot- diameter stone-, boulder- and sand-filled cylinders

Posted on July 3, 2024

After the 116,851-ton container ship Dali slammed into the Francis Scott Key Bridge, collapsing it into the Patapsco River, an alarming fact became widely known: The structures designed to protect it from ship strikes installed half a century ago were no match for the huge vessels plying the waters today.

The Maryland Transportation Authority, which owns the Key Bridge, never upgraded the original system of small protective cells near its piers as cargo ships quadrupled in size over the years.

Maryland officials have yet to say whether they ever explored such improvements. But if they’re seeking an example of an agency that took that step, they need only look one state away.

About 75 minutes from Baltimore, a mile or two south of Wilmington, Delaware, workers are nearing the halfway point of a 26-month, $95 million project to replace the pier protection system at the foot of the Delaware Memorial Bridge. The heavily trafficked span carries about 100,000 vehicles per day over the Delaware River between Delaware and New Jersey and is an indispensable link in the Interstate 95 corridor between the mid-Atlantic, New York and points beyond.

Because of its cost, a lack of political will and the fact that it may never be needed, such an upgrade rarely happens.

But officials with the Delaware River and Bay Authority, the agency formed in the 1960s that owns the bridge, made it happen. The story of how they did has as many twists and turns as a freighter’s route through Wilmington and Camden to the Port of Philadelphia.

The authority spent years weighing the upgrade. A grant from the U.S. Department of Transportation got the wheels turning. And by the expected completion date of September 2025, the system will feature eight massive “dolphins” — sand- and stone-filled cylinders that serve as protective islands — designed to keep ships even larger than the Dali from damaging its four support piers.

It will be one of the few existing U.S. bridges to deploy an upgraded pier protection system strong enough to absorb the force of most of today’s oceangoing vessels. Those who worked on the project say that as hard as the process has been, the result will be more than worth the effort.

“Our original fendering system was good for the ’50s and ’60s, but we don’t live in the ’50s and ’60s anymore,” authority spokesman James Salmon said. “Given all the new technologies and the speed of these new ships, you’ve got to be prepared.

“We hope and pray the system will never be needed, of course, and the odds are it won’t be, but if it is needed, it will be there. We look at it as our $95 million insurance policy.”

Dire need

Somewhere between 60% and 70% of the bridges with piers in navigable waterways in the U.S. have no pier-protection structures of any kind, according to Hyunjoong Kim, a structural engineering professor at Liberty University who specializes in the subject. And most of the 30% to 40% that do — including the Key, Chesapeake Bay and Delaware Memorial bridges — were built before 1991, the year the federal government first issued guidelines on the matter.

That’s why the effectiveness of even those systems — such as the 25-foot-wide dolphins at the foot of the Key Bridge that one engineer described as “kids’ toys” — “remain uncertain,” Kim said.

The container ship Dali dwarfs the protective dolphin in the Patapsco River to its right in this April 1 photo of the wreckage of the Francis Scott Key Bridge almost a week after the vessel hit a structural pier causing the bridge to collapse. (Jerry Jackson/Staff)

The need for robust protective structures borders on the dire — and most in the industry have known it since the 1980 disaster at the Sunshine Skyway Bridge in Florida. A freighter hit a support pier during a squall, knocking a 1,200-foot span into Lower Tampa Bay and killing 35 people.

“The Tampa Bay incident was very well known, very famous,” says Andrzej Nowak, a structural engineering professor at Auburn University. “After that happened, there is a strong argument to be made that doing nothing [to improve pier protection] should have been off the table.”

Close call leads to action

Eleven years before the Sunshine Skyway debacle, in 1969, a 715-foot-long Texaco Oil tanker, the Regent Liverpool, went off course and struck a support pier of the Delaware Memorial Bridge, a suspension bridge with a newly added second span. Its piers were protected only by narrow granite islands wrapped in steel plating.

The fenders did their job, said Greg Pawlowski, the senior project engineer in charge of the current upgrade project. Though repairs cost $1 million ($7 million in today’s dollars), the pier escaped damage, and no one was hurt.

But the collision made it clear to authority officials that no matter how rare it is for a large vessel to strike a bridge, it can and does happen. And should it happen, the results could easily be far worse than a shorn fender.

“While other people were saying, ‘What is the chance of our being hit?’ we were saying, ‘We’ve already been hit. We could get hit again!’”  Pawlowski said. “We started looking into making the commitment.”

It was two years after a new bridge was completed in Tampa in 1987, complete with a cutting-edge arrangement of cement bumpers and 36 huge dolphins, that Pawlowski’s predecessors commissioned a study on the feasibility of upgrading the Delaware Memorial Bridge’s pier protection system. Four others followed between 1995 and 2014.

The Delaware River and Bay Authority included the idea as part of its capital improvement plan in 2014, and in 2017 it commissioned the Center for Homeland Defense and Security, a Navy graduate school, to conduct a tabletop exercise involving a ship hitting the bridge.

Later that year, the authority — formed by a compact between Delaware and New Jersey — learned the U.S. Department of Transportation had established a fresh grant program to help states meet infrastructure needs. It made $1.5 billion available over a seven-year period starting in 2018 for infrastructure projects that “directly affect public transportation.”

Protective dolphins are being constructed around the support piers of the Delaware Memorial Bridge. The project began in 2023 and when completed in 2025, will consist of eight 80-foot-diameter stone-, boulder- and sand-filled cylinders. (Jerry Jackson/Staff)

Pawlowski, Salmon and company put together an application that laid out their argument. They estimated it would cost $44.5 million to construct a dolphin system strong enough to repel cargo vessels weighing up to 120,000 deadweight tons. They contrasted that figure with the $930 million their insurance companies said it would cost to replace either tower. And that didn’t include the billions in economic damage any collapse would cause.

The U.S. Transportation Department came through with a $22.5 million grant, the 16th largest of the 91 it doled out in 2018. To officials at the semi-independent Delaware River and Bay Authority, which like its Maryland counterpart draws no state funding and relies almost exclusively on toll revenues, it was a mighty sum. Pawlowski was convinced it was time to move forward.

“All we had to do was come up with 50% of the money,” he said. “At some point in time, you’ve just got to bite the bullet and act.”


On a breezy, sunlit morning in June, Pawlowski, a 61-year-old math whiz with an irreverent sense of humor, walked a visitor onto a temporary platform that juts into the river below the 13,500-foot-long Delaware Memorial Bridge.

Pawlowski gestured across the water toward the four massive piers, two each for the eastbound and westbound spans. Most are still wrapped by the fenders installed upon completion of the bridge’s second span in 1968. Then he points to two of the dolphins that workers from R.E. Pierson Construction, a New Jersey-based general contractor, have all but completed on the west side.

Rust-colored, as wide as an eight-story building is tall, and towering above the water, each is packed with 15,000 cubic yards of sand and will contain 400 cubic yards of boulders and 140 cubic yards of stone. Sheet pilings 110 feet long penetrate 50 feet of water and sink it into 45 feet of silty clay and 10 feet of dense sand on the river bottom.

Two others on the west side hang high on their templates, not yet pile-driven through the mud.

Protective dolphins are being constructed around the support piers of the Delaware Memorial Bridge. (Jerry Jackson/Staff)

“It’s hard to put their size in perspective until you see them up close, right?” Pawlowski said. “As you can tell, these things are enormous.”

The design criteria are based on standards laid out by the American Association of State Highway Transportation Officials.

Pawlowski groused that it took a whole year to get the federal grant executed. Then came the COVID-19 pandemic, a calamity that clogged supply chains, triggering a more than 250% hike in the price of American steel that still shocks the engineer. By the time the authority bid the project out, the lowest offer was for $116 million, more than twice the original estimate.

At a series of meetings, agency engineers and consultants considered dropping the idea, Salmon said, but were loath to forgo a $22.5 million federal windfall. The massive cargo vessels that kept chugging by on the Delaware served as a constant reminder that the situation was urgent.

Close scrutiny of the low bid, Pawlowski said, showed the issuer had assumed a level of robustness the engineers didn’t need — the proposed dolphins would have survived large vessel strikes — and by allowing Pierson to consult in the design process, they brought the price down to $92 million. That was enough to win “yes” votes from the required four of the six commissioners from each state — as well as the signatures of the governors of Delaware and New Jersey. (Design and permitting requirements later added $3 million to the cost.)

The agency is on course to raise the remaining $72.5 million by selling revenue bonds and increasing the cost of tolls for some drivers in the near future.

It’s hard to know exactly why authorities decided to commit to the investment when their counterparts in other states typically do not, Pawlowski said. He believes the persuasiveness of two veteran structural engineers, Shoukry Elnahal and Shekhar Scindia, who joined the authority’s leadership late in their careers, helped.

Meanwhile, the project rolls on. A barge carrying all the steel for dolphins on the bridge’s east side arrived from Louisiana at the end of June, and workers have resumed pile driving after observing a 3 1/2-month hiatus mandated by the federal government to protect the endangered Atlantic sturgeon during its migrating season.

Thanks to the standards for new bridges established in the 1990s, Pawlowski said, the Key Bridge replacement will be required to have more robust pier protection systems than its predecessor. And Maryland transportation authorities say they’re considering adding new ones to the Bay Bridge, a project he believes would cost $100 million or more.

Asked whether he had any advice to give those who would make the call, Pawlowski’s reply was simple.

“Get started as early as you can,” he said. It’s a big, big process.”

Traffic crosses the Delaware Memorial Bridge. (Jerry Jackson/Staff)


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