Would California bridges stand up to a direct hit? Quake preparations will probably help
Jenny Jarvie Grace Toohey Rachel Uranga March 26, 2024
Baltimores Francis Scott Key Bridge stood little chance of survival Tuesday when a cargo ship rammed into it: Its vertical support structure seemed flimsy for a bridge spanning such a busy port, experts said, and did not appear to be protected by a substantial impact barrier.
Tuesday’s incident happened just before 1:30 a.m., when a 948-foot-long cargo vessel dubbed Dali lost power as it was leaving Baltimore’s port at a speed of 8 knots. After the ship rammed into one of the bridges support piers, the structure began to shatter almost instantly.
Within seconds, the southern and central spans of the bridge began to collapse. Then the northern span. In 25 seconds, the entire bridge had plunged into the
Patapsco
River.
Papatsco River.
Officials say six members of a construction crew working on the bridge were still unaccounted for as of Tuesday afternoon, and other victims could still be discovered.
But experts say the Baltimore collapse does not expose significant vulnerabilities in the major bridges near ports across California, which has the two busiest
ports
in the nation: the Port of Los Angeles and the Port of Long Beach, which handle about 40% of U.S. container imports from Asia. Los Angeles port saw 1,712 vessels arrive in 2023.
Dr. Robert Dowell, an associate professor of structural engineering at San Diego State University, said California’s major bridges are less at risk of being toppled by errant cargo ships because their support columns have been retrofitted to make them withstand major earthquakes.
“If they were seismically retrofitted, they would be strengthened and you wouldn’t expect as fragile vertical members as what you saw supporting the Baltimore bridge,” Dowell said.
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California’s major bridges typically have solid supports and substantial bumpers that offer the bridge protection from a collision, Dowell said.
The Francis Scott Key
b
Bridge, Dowell said, seemed vulnerable for a structure in such a key shipping hub. Its support pier did not appear to have a large enough bumper surrounding it, he said, and the pier itself was not one solid structure, but made up of multiple vertical members. It appears from zoomed-in video of the bridge collapse that the ship impact
caused the failurefailed one
of
one of
these vertical members first, overloading the rest of the vertical members at the one pier, resulting in the subsequent complete collapse of the main span.
Such a vertical support, Dowell said, was “a little bit unusual to be so fragile when huge ships are coming through the shipping channel. However, even for such a fragile pier, if a proper bumper was provided around the base of the pier, it would have protected the pier from direct impact and saved the bridge
, he said.
You would think, if that’s where the large ships are supposed to go, you would have that protected, for sure,” Dowell said. “If it was a solid, reinforced concrete column … supporting the bridge, it probably wouldn’t have collapsed in this case, Dowell added, even without a proper bumper.
It’s not quite fair to compare the two Southern California bridges near the states largest ports with the collapsed Baltimore bridge, said James Fawcett, an adjunct professor of environmental studies at the University of Southern California who worked for years with USCs Sea Grant Program, where he focused on ports and shipping.
The Vincent Thomas and Long Beach International Gateway bridges are significantly shorter than the Key bridge in Maryland, he said, and their positioning in relation to the California ports minimize concerns about bridge damage.
Typically, container ships can access the
p
Port of L.A. and
p
Port of Long Beach without ever going under a bridge, Fawcett said.
He said the California port with the most similarities though still hard to directly compare would be the Port of Oakland, as most large ships there have to navigate under the Golden Gate Bridge and the San Francisco-Oakland Bay Bridge, the latter
of
which has multiple supports across the bay.
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Khalid M
.
Mosalam, professor of civil engineering and the
D
director of the Pacific Earthquake Engineering Research Center at UC Berkeley, said Californias focus on seismic design as it retrofitted bridges since the late 1980s and early 1990s made its bridges more resilient.
Whether they are able to take such a huge impact, I’m not sure, Mosalam said. But definitely they are more robust and larger than the support I saw in some of the images.
Installing bumpers, he said, also played a big role in minimizing damage.
The fender system will reduce the impact for sure, because it will dissipate some of this big energy due to the impact. It’s like the shocks you have in your car when you hit a bump in the road and absorb some of this energy and you don’t feel it that big.
In 2007, the Bay Bridge narrowly escaped major damage from a large container ship that sideswiped a pier support, leaving a gash nearly 100 feet long in
on
the side of the ship, breaching fuel tanks that set off a major oil spill. While the spill was devastating to the
B
bay, the 8.4-mile bridge and its stability were not affected, according to a National Transportation Safety Board report.
The collision did however damage the fendering system that surrounds the base of the support tower, which helps protect the bridge from a ship or other impact. The system was repaired, but the Metropolitan Transportation Commission, which oversees Bay Area transit, is seeking federal funds to further update and improve it, according to spokesperson John Goodwin.
He said a catastrophe like the one in Baltimore could conceivably happen in Oakland, as seen in 2007.
A few years ago, it damn near did,” Goodwin said. Thank heavens for the fenders we have at the Bay Bridge and elsewhere that protected the Bay Bridge back in 2007.”
The only ports in the Golden State that see those large container ships as large as the Dali are the Port of Hueneme in Oxnard and the Port of San Diego, Fawcett said, but neither have bridges that span typical port operations.Not LA or LB?
Fawcett said he was surprised, based on the videos he saw, that the container ship in Baltimore had so few tugboats helping the ship navigate through the narrow waterways.
She apparently didnt have adequate tugs for this situation, Fawcett said. It would have been wise perhaps to have more tugs assisting the vessel.
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Cargo ships have gotten larger over the decades, with many easily weighing more than 100,000 tons.
You would think, if that’s where the large ships are supposed to go, you would have that protected, for sure, Dowell said.
Andy Herrmann, past president of the Structural Engineering Institute, agreed the Baltimore bridge did not appear to have a substantial buffer or enough column support to sustain a vessel crash.
It looked like they had cylindrical piles going down, but they were not very large, Herrmann said.
Mehni Kashani, an associate professor of structural engineering at University of Southampton in London, also said he was surprised to see as far as he could tell in the video that robust ship impact barriers did not surround the supports.
If there was a ship impact barrier, the ship wouldnt [have] hit the bridge, Kashani said.
Bridge specifications changed in the 1990s to account for collisions from massive cargo vessels like the one that killed 35 people along the Sunshine Skyway Bridge in Florida in 1980.
A seagoing freighter
,
as long as two football fields
,
slammed into a support pier and the bridge connecting Lower Tampa Bay to St. Petersburg. The collapse plunged a Greyhound bus and seven other cars into the bay.
When they rebuilt it, they actually put an island in front of the piers, so that
the
any shipping [vessel] that would get close to the piers, that could possibly take it down, went aground before they hit it, Herrman
n
said.
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Kashani said such barriers have become common practice in bridge construction around the globe, ensuring that if a nearby ship veers off course, any impact still wouldn’t affect a key bridge support. He has worked on constructing such barriers for bridges and structures along the River Thames, which connects Londons largest port to the Atlantic Ocean.
Luckily, Kashani said, retrofitting a bridge to add ship impact barriers, while costly, is possible to do without directly affecting a bridge, because the barriers can be built around
an
existing supports.
San Franciscos Golden Gate Bridge, despite being built in 1937, has a barrier around its south support tower, which sits on a pier mid-channel most directly in the path of ship traffic, according to Paolo Cosulich-Schwartz, the spokesperson for the Golden Gate Bridge Highway and Transportation District.
The bridges north tower sits partly on land, and any large ship would run aground before colliding with it, he said.
The Golden Gate Bridge has the most robust ship collision protection of any bridge on the West Coast, Cosulich-Schwartz said. Theres basically a moat or buffer zone around the [south tower] pier.
That barrier, he said, protects an area of the size of a football field with a bumper made of concrete and filled with sand.
Despite shipping containers regularly passing under the iconic bridge, Cosulich-Schwartz said that it would be highly unlikely for a wayward boat to affect it, noting that even though the barrier is from the bridge’s original construction, recent inspections have found it in good condition.
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“Were confident that the system is strong and would protect the Golden Gate in the case of an incident similar to the one we saw in Baltimore, he said.
In Southern California, the Long Beach International Gateway a bridge that connects Terminal Island and Long Beach near the ports of Long Beach and Los Angeles has supports only on land, so its impossible to hit that bridge, said Capt. James Kipling Louttit, executive director of the Marine Exchange of Southern California, which provides vessel traffic services for the port.
He said it’s not unusual for vessels weighing over 100,000 tons to dock in the ports.
The other nearby span, the Vincent Thomas bridge which connects San Pedro to Terminal Island has supports in the water, but they are both positioned very close to land.
The Baltimore ships 22 crew members, including two pilots, were all accounted for and no injuries were reported, according to a
from Synergy Marine Group, a Singapore-based company that manages the ship, which was en route to Colombo, Sri Lanka.Authorities responded to the scene after the ships crew alerted notified Maryland officials they had lost control of the vessel, Gov. Moore said, allowing officials to stop traffic and prevent more cars entering the bridge.Many of the vehicles were stopped before they got on the bridge, which saved lives, Moore said.
