A car traverses the Casco Bay Bridge, coming from the South Portland end on Wednesday. Below, a large, concrete "dolphin" protects the bridge from ship strikes. Credit: Troy R. Bennett / BDN

PORTLAND, Maine — Though ships carry cargo containers and oil tanks through Maine’s waters, officials say the state is unlikely to see a catastrophic crash like the one that collapsed a bridge in Baltimore this week.

But it’s not entirely out of the question.

“Every precaution is taken,” Portland Harbor Master Kevin Battle said. “But we’re only human, no matter how much we strive for perfection.”

Such a disaster is far less likely in Maine for three key reasons. First, the state has less shipping traffic than Baltimore. Second, not all big vessels pass under Maine’s bridges, as they must in Baltimore Harbor. Finally, the fuel and cargo ships stopping here are far smaller than Baltimore’s.

Maine’s three major cargo ports in Portland Harbor, Searsport and Eastport handled a combined 6.5 million metric tons of cargo in 2023, compared with 11.7 million tons during the same time period in Baltimore, according to the Maryland state archives.

And while all cargo vessels coming and going from Baltimore must pass beneath the harbor-spanning Francis Scott Key Bridge, Maine benefits from having very few bridges over its established shipping routes.

Ships heading up the Penobscot River must pass beneath the Penobscot Narrows Bridge, whether they’re hauling oil to a terminal in Bucksport or manufactured construction modules from a Cianbro Corp. facility in Brewer, according to David Gelinas, president of the Penobscot Bay & River Pilots Association.

But the bridge, which opened in 2006, is anchored on both sides of the river and doesn’t have piers that could be struck by vessels, Gelinas said. He also noted that vessels that use the river tend to have plenty of clearance below the deck of the bridge, which is 135 feet above.

Of the state’s three established cargo ports, only Portland Harbor has a bridge which ships must navigate: the Casco Bay Bridge, a draw span connecting Portland and South Portland. And only six of the harbor’s 10 marine terminals are on the far side of that bridge, limiting how much shipping traffic must go through it.

A large, concrete “dolphin” juts out into Portland Harbor, protecting the Casco Bay Bridge from ship strikes on Wednesday. Container ships servicing the International Marine Terminal, seen in the background, do not pass beneath the bridge. Credit: Troy R. Bennett / BDN

Last year, according to Maine’s Department of Transportation, the bridge opened 680 times, letting vessels pass through.

On that side of the bridge, where Portland Harbor meets the Fore River, are the Merrill Marine terminal, which handles bulk materials including scrap metal, salt and sand; and Turners Island terminal, which moves general cargo and has rail connections. Also beyond the bridge are four petroleum shipping facilities run by various companies.

On Wednesday, the only cargo vessel docked beyond the Casco Bay Bridge was the Great Eastern, an oil tanker that arrived that day from Saint John, New Brunswick. According to registration records, the Great Eastern is 600 feet long and 88 feet wide. That’s just over half the size of the Dali, the ship which brought down the Key Bridge in Baltimore. It’s listed as 985 feet long and 157 feet wide.

The Dali is also listed as being able to transport almost 10,000 containers on a single voyage, meaning it would take just 4.5 trips for it to deliver the total number of containers — 44,000 — as Portland’s busy International Marine Terminal handled in all of 2023.

Battle, the harbormaster, points out many ships passing through the Casco Bay Bridge’s 196-foot drawspan aperture aren’t making the trip unassisted, either.

“Tugboats — sometimes one at the bow and one at the stern — are used as needed for vessels with limited maneuverability,” Battle said.

The bridges over Portland Harbor have not been totally immune to harmful ship strikes. In September 1996, a Liberian-flagged oil tanker called the Julie N. struck the Million Dollar Bridge that had been built over the harbor in 1916.

The Julie N. was 85 feet wide and the Million Dollar Bridge’s drawspan clearance was only 95 feet, giving the boat just five feet on either side. Oil was spilled in Casco Bay, but the bridge was not seriously damaged. It was soon replaced by the Casco Bay Bridge, which was under construction at the time of the strike.

One of the questions that’s now facing authorities investigating the collapse of the Key Bridge is whether it had adequate protection against ship strikes. Bridge engineers typically design structures known as fenders to protect the piers that hold up critical supports on a bridge. Some experts are suggesting that the fenders around the Key Bridge were not robust enough to stop a large ship, according to The New York Times.

An airplane flies through the sky over the undulating curves of the Casco Bay Bridge’s South Portland end on Wednesday. Though the bridge spans Portland Harbor, large ships only pass through the relatively small aperture of the drawbridge apparatus. Credit: Troy R. Bennett / BDN

But in Portland Harbor, officials say that the Casco Bay Bridge does have adequate protection. Battle noted that it’s able to resist the occasional contact with ships.

“The bridge gets sideswiped from time to time, but the fender system does its job and protects the bridge,” Battle said.

Joyce Taylor, chief engineer with the Maine Department of Transportation, told CBS 13 the Casco Bay Bridge was built with safety in mind. It has a sophisticated series of large, concrete protective “fender and dolphin” systems for both coming and going vessels.

“They’re really sacrificial, to absorb the energy of a ship hit,” Taylor said, “so that the bridge won’t be compromised.”

That safety feature was an upgrade from the less modern piles of granite stone that protected the Million Dollar Bridge. Taylor said the newer, larger protections give her complete peace of mind.

“I’m very comfortable that the bridge is safe,” Taylor said. “I’d go over it with my grandchildren.”

The Casco Bay Bridge also receives far less car traffic than the Key Bridge, as well. The Maine Department of Transportation puts the daily average at 13,000, while the Key Bridge averaged closer to 30,000 cars every 24 hours.

BDN editor Charles Eichacker contributed to this report.

Troy R. Bennett is a Buxton native and longtime Portland resident whose photojournalism has appeared in media outlets all over the world.