There are contradictory reports on some key facts regarding the container ship MV Dali destroying Baltimore’s Francis Scott Key Bridge. For instance, the Wall Street Journal quoted an officer of the saying they did not drop anchors, while a shipping expert reported on YouTube that a helicopter had taken and circulated an image of port anchor being deployed but he was not sure about the starboard. Similarly, the BBC reported that the state governor said the vessel was going very quickly, when other commentators have said the reverse (and with a pilot from the port aboard to direct the ship, speeding would seem unlikely).
Nevertheless, even with a less than full picture of what happened, we might be able to pose some productive questions now.
One of the tacit assumptions in much of the coverage is that this event was a Black Swan, or more colloquially, an extreme case of Shit Happens. However, that perspective can divert attention from the notion that there was operational and/or safety corners-cutting that made an event like this too likely given the (heretofore hidden) risks being taken. Naked Capitalism readers, having higher expectations for what passes for our betters, instead took this as yet another sign that we are not a serious country.
The very short version of what happened, as you can track in some of the narrated videos, is that the ship lost power when very close to the bridge, appeared to get it back briefly (which belching of smoke) but looked to be out of control and soon swung out of its channel and into the bridge pier”
Some of the issues:
Why did the power fail? The ship is normally powered by a diesel engine. When the lights came back on and the ship belched smoke, that may have been a restart of the engine. An exclusive Wall Street Journal story says investigators are looking at dirty fuel as a cause. Recall the vessel has passed regular inspection with only minor problems cited. But if this ship got engine-busting bad fuel, why aren’t there other cases?
Why was there no backup capable of very quickly restoring navigation? Again we don’t have a clear picture yet, but the big belch of smoke suggests the crew either tried to restart the engine or perhaps an auxiliary diesel engine. But that sort of process has to take time when there is never enough time in an emergency. It appears there was no battery backup. This is something to watch for as more blow-by-blow reconstructions emerge.
From BBC:
The National Association for Pilot Profession has provided some more details on the ship that crashed into the Baltimore bridge.
The association says the ship lost full power, with no lights, no electronics and no engine propulsion, making it essentially a “dead ship” within 20 to 30 seconds.
The group says lights came back on in the ship thanks to an emergency generator, but that doesn’t give the engine power. Video shows lights flicker back on briefly before the vessel hits the bridge.
Black smoke that billowed from the ship around this time was likely an emergency diesel generator kicking in, the pilot group says
From reader scott s. in comments (emphasis added):
First off, my professional background is US Navy marine engineering, not commercial….
Ships like this use a slow-speed direct coupled diesel that does a max of 90 rpm or so, designed entirely for fuel efficiency. The diesel is remotely controlled via a local control panel. AFAIK typically intended for unmanned operation, though I don’t know if a watchstander is required for entering/leaving port. I assume the local control panel and individual cylinder controls are battery-backed for loss of power…
Ship’s service AC power would be via separate diesel generator with emergency diesel or battery as backup. Certainly the steering motor has normal and emergency power source. In USN practice we use AC motor-driven redundant hydraulic pumps. We have the ability to hand pump the hydraulics (and also set the direction of travel manually) but it’s slow. Actually there is also a big nut on a screw thread alongside the ram and a monster wrench that can be used in last resort to force the rudders into position.
All the control circuitry (helm to rudder and EOT to engine) should be battery-backed.
Did the pilot have any control over the ship after the power failure? The Wall Street Journal says not:
A harbor pilot and assistant reported power issues and a loss of propulsion before the crash, according to a Coast Guard briefing report viewed by The Wall Street Journal.
“The vessel went dead, no steering power and no electronics,” said an officer aboard the ship Tuesday. “One of the engines coughed and then stopped. The smell of burned fuel was everywhere in the engine room and it was pitch black.”
With everything dark and presumably communications within the ship impaired (and this source apparently in the engine room), a single source could have some details wrong. Note that the shipping expert above points out in the video above that if the power had come back sufficiently to regain control of navigation, and the ship had tried to “back off” which I take to mean go into reverse to cut the speed, that would result in the ship careening and so would not have prevented, and could even have helped cause, the crash.
This video overlaps with the one above but has good detail on what the ship’s crew might have done with when the power went out:
scott s. also explained why dropping the anchor wouldn’t/didn’t prevent the disaster:
It was mentioned they did drop an anchor which is also standard naval practice. But just putting an anchor “underfoot” doesn’t provide much holding power. You need to veer chain so the mass of chain works against motion.
Why weren’t tugs used to escort ships, or at least big honker potentially bridge-destroying ships, past the bridge? The news stories say that in the Baltimore harbor, tugs normally only help vessels get in and out of berths. I will have to recheck with Lambert, who has spoken often with a tugboat operator in New York City’s harbor, but the impression I have second-hand is that the New York City tugboats do a fair bit of escorting in the harbor.
The reason this might not be an unreasonable question give the lack of past disasters is that the riskiness of ships going in and out of harbors has likely increased. One has to assume that average sizes have increased, and perhaps also the number of ships going in and out of a port in any year. If you watch the first video above, it looks as if the Dali had barely gotten out of its channel when it hit the pier. If so, that would indicate the margin for error with a pretty big vessel was not that large.
Of course, we know the answer is “because cost”. But if you view tugs as insurance, it now looks as if even many many many years of tugboat assistance would still come in cheaper than the cost of the loss of the harbor during bridge clean-up, the cost of diverting land traffic, and the expense of rebuilding the bridge.
Lambert also notes, and I have not confirmed, that the original proposal was for a tunnel under the harbor, but a bridge was cheaper. That now looks like another false economy.
Was the bridge design or construction deficient? From reader Glenn Olson, in comments:
I’m amazed at how few seconds it took for the bridge to collapse into the water and how many pieces it broke into. As an engineer I’m at a loss to understand the tradeoffs that were made in the design such that loss of one support resulted in so many shear points and total loss of the center span. It’s almost like it was made of glass and shattered at the first impact. Steel designs should not do that.
Reader bob opined that it’s just not possible to design a bridge to withstand this kind of impact. Perhaps that is correct, but Alexander Mercouris regularly claims that bridges are seriously over-built. I am not sure what the analogous terms are in the bridge world, but buildings are designed to handle compression load, wind load on each face of the building (and for eccentric designs like Citicorp Center, rotation load) and again for skyscrapers in New York City, the impact of small aircraft.
But it appears handling impact, such as not collapsing catastrophically, was not a design consideration here. For instance, the bridge appear to have not “dolphins” as in protective underwater structures to take the impact of a ship collision. From Maritime Executive:
Wednesday’s disastrous bridge collapse in Baltimore brought to mind lessons learned in 1980, when the freighter Summit Venture struck and destroyed half of Tampa’s Sunshine Skyway bridge. 35 people died in that disaster, prompting a decade-long rethink of highway bridge design. The Skyway Bridge was rebuilt with a fortress of protective concrete dolphins – but it is unclear whether Baltimore’s Francis Scott Key Bridge was updated to meet a similar standard before it was hit by the boxship Dali on Wednesday morning.
Baltimore’s Key Bridge opened in 1977, three years before the Skyway Bridge disaster (and two years after a similar casualty in Tasmania). Based on visual evidence, the Key Bridge had one small dolphin on each side of the central span’s piers, intended either for scour protection or for defending against allisions. When the container ship Dali approached early Wednesday morning, the vessel appeared to pass by the dolphin and strike the pier directly with her starboard bow.
“Maybe [the dolphin] would stop a ferry or something like that,” consulting engineer Donald Dusenberry told the New York Times. “Not a massive, oceangoing cargo ship.”
Tampa-area attorney Steven Yerrid was involved in the response to the Skyway Bridge disaster in 1980, and he told local media that when he saw the fendering system on the Key Bridge, it looked all too familiar. “I felt not only shock, but extreme sadness, because I knew other people had to unnecessarily lose their lives to learn a lesson that was taught 44 years ago,” Yarrid told Tampa’s Fox 13.
The Skyway Bridge’s lessons were written down and codified by AASHTO, America’s highway standards body, in 1991….
For many engineers, the fact that a landmark structure like the Key Bridge could still be felled by marine traffic is a call to action. “As a matter of principle, when there is a bridge pier in a shipping channel we should expect the bridge to be strong enough to withstand impact or to be protected from impact,” structural engineer Shankar Nair told the Baltimore Banner.
Mind you, the dolphin question is separate from the one raised by Glenn, which is even more germane given the lack of ship-protections like dolphins. Shouldn’t the design and construction provided for enough structural integrity so that a severe hit to a pier would result in only a partial bridge collapse?
Right now, we have more questions than answers. And the questions above may not be the best formulated. But it’s important to keep key issues front and center to understand why this happened and what to do to prevent its recurrence.