Baltimore Bridge Collision and Collapse

[boatgeek]

The Key Bridge in Baltimore was hit by a container ship last night and collapsed. Fortunately, it was in the middle of the night so there was less traffic on the bridge. At least two people have been recovered from the water, and several are still missing. This is the moment when statics moved on a semester and became dynamics.



I hope all of the TRF community and their family and friends are safe.

 

[DAllen]

I see elsewhere that some think this is an example of the disrepair of our infrastructure. I'm not sure this is the greatest example. You really shouldn't need to design bridges for head-on collisions to the piers from giant container ships...but now we will have to.

 

[NTP2]

How did they not see the bridge?!

 

[cls]

some news reports the ship lost power and called Mayday before hitting the bridge.

 

[jsdemar]

My daughter lives about 15 miles from the bridge. Good thing it happened at 1:40am.

The ship lost power and the crew (from India) sent a mayday call ahead of the collision. That stopped more cars from being on the bridge. There were construction workers filling potholes at the time, only 2 of 10 were rescued. They say there are still several cars submerged showing up on sonar.

 

[David_Stack]

Some reports indicate that the vessel suffered an electrical outage that impacted their navigation/steerage, BUT the power appeared to be restored prior to the collision, yet the ship failed to execute a course correction. I'm sure there will be no shortage of investigation...

Sniped by "cls"

 

[NTP2]

You’d think they would have a emergency backup but apparently not.

 

[MClark]

Baltimore Harbor Pilots were driving ship.
But if engine quit nobody was steering.

 

[DAllen]

How did they not see the bridge?!

I'm betting they saw the bridge and knew they were going to hit it and due to the power outage on the ship there was nothing the crew could do about it.

And I am seeing elsewhere on the interwebs that some think this is some sort of grand conspiracy to erase Francis Scott Key's legacy. If for some that's the first conclusion made without waiting for the results of the inevitable NTSB investigation which will be factual...well...they're not very smart. Of all the incredibly stupid conspiracies society has been tortured with over the last 4-5 years this would be hands down the dumbest.

 

[jderimig]

@boatgeek You might know. From the video it appears when the ship went dark the ship seemed to quickly turn starboard. What would cause it to turn like that in a power loss? Currents? I would think Newton's laws would apply.

Edit: Rewatched the video. After the first power loss (lights out) Newton's Law seemed to apply. Ship kept on course. When power was restored (lights on) is when the ship veered toward the pylon.

 

[DAllen]

That ship is huge...yikes

 

[Aeva]

I'm betting they saw the bridge and knew they were going to hit it and due to the power outage on the ship there was nothing the crew could do about it.

And I am seeing elsewhere on the interwebs that some think this is some sort of grand conspiracy to erase Fancis Scott Key's legacy. If for some that's the first conclusion made without waiting for the results of the inevitable NTSB investigation which will be factual...well...they're not very smart. Of all the incredibly stupid conspiracies society has been tortured with over the last 4-5 years this would be hands down the dumbest.

What I find more amusing is BBC actually had a report on the bridge. Francis Scott Key is famous because he consequently wrote a poem about the British invasion during the war of 1812... do you think the reporter knew who the bridge's namesake is?

But also... the bridge has less to do with his legacy and I bet millions of Americans didn't even know there was a bridge named for him before it collapsed. Conspiracy theorists are wild...

 

[jsdemar]

@boatgeek You might know. From the video it appears when the ship went dark the ship seemed to quickly turn starboard. What would cause it to turn like that in a power loss? Currents? I would think Newton's laws would apply.

Edit: Rewatched the video. After the first power loss (lights out) Newton's Law seemed to apply. Ship kept on course. When power was restored (lights on) is when the ship veered toward the pylon.

There are likely underwater structures leading up to the bridge supports which may have influenced the ship's path when close to the support. Or, the steering was commanded in that direction before it lost power; upon regaining power, there's a control lag to correct it. Or human error.

 

[jderimig]

That ship is huge...yikes

View attachment 637242

I guess we now know how far away we will need to install the bollards away from bridge pylons that will be part of a new infrastructure projects.

 

[Aeva]

@boatgeek You might know. From the video it appears when the ship went dark the ship seemed to quickly turn starboard. What would cause it to turn like that in a power loss? Currents? I would think Newton's laws would apply.

Edit: Rewatched the video. After the first power loss (lights out) Newton's Law seemed to apply. Ship kept on course. When power was restored (lights on) is when the ship veered toward the pylon.

Best guess? Rudder is controlled by the cargo ship equivalent of power steering and changing the direction of the rudder without power steering required more muscle. They probably lost power mid turn, and you can see they try and straighten their path after power is back and before hitting the pylon.

E: I had a hard time finding a video showing the moments before the collapse

but you can see it here.

 

[cvanc]

Sal Mercogliano is on it, as usual, here's his initial examination

 

[boatgeek]

I see elsewhere that some think this is an example of the disrepair of our infrastructure. I'm not sure this is the greatest example. You really shouldn't need to design bridges for head-on collisions to the piers from giant container ships...but now we will have to.

No, this isn't an issue of infrastructure. Bridges aren't designed to take hits from ~100,000 ton objects. Very few things are.

My daughter lives about 15 miles from the bridge. Good thing it happened at 1:40am.

The ship lost power and the crew (from India) sent a mayday call ahead of the collision. That stopped more cars from being on the bridge. There were construction workers filling potholes at the time, only 2 of 10 were rescued. They say there are still several cars submerged showing up on sonar.

You’d think they would have a emergency backup but apparently not.

They would have an emergency generator on board. The rules on that are a little complicated, but the emergency genset and backup steering power should have been online within 45 seconds of a power failure. However, if they lost power, the main engine may also have gone down. I believe that many engine auxiliaries (like fuel pumps, for example) are electrically powered on these big engines instead of being run by a belt off the engine itself. The rudders are far less effective if they don't have prop wash flowing over them.

And that's if everything was working properly. It is not uncommon for ships to have broken emergency gensets, though that's typically less of an issue with ships working for the big shipping lines (this ship was chartered by Maersk).

@boatgeek You might know. From the video it appears when the ship went dark the ship seemed to quickly turn starboard. What would cause it to turn like that in a power loss? Currents? I would think Newton's laws would apply.

Edit: Rewatched the video. After the first power loss (lights out) Newton's Law seemed to apply. Ship kept on course. When power was restored (lights on) is when the ship veered toward the pylon.

Newton's laws are harsh mistress for something this big. Turning radius for these ships is measured in miles. And the loss of 45 seconds of steering at the wrong time can easily send you out of a relatively narrow channel.

Best guess? Rudder is controlled by the cargo ship equivalent of power steering and changing the direction of the rudder without power steering required more muscle. They probably lost power mid turn, and you can see they try and straighten their path after power is back and before hitting the pylon.

All steering on this size ship is hydraulic or electric. People don't have enough power. Once electrical power was lost, they had no means of moving the rudder until it was back on.

 

[Aeva]

All steering on this size ship is hydraulic or electric. People don't have enough power. Once electrical power was lost, they had no means of moving the rudder until it was back on.

Thought as much... I bet a tug-o-war team would meet its match versus a cargo ship rudder.

 

[Banzai88]

You’d think they would have a emergency backup but apparently not.

I worked in the ship repair industry for a few years, specializing in cleaning and servicing and modernization of main power distribution onboard commercial vessels.

The emergency backup is an emergency diesel generator that kicks in, but it takes time and only powers certain things, many others have to be switched over manually.

In the video, you can see the EDG start up, it's that puff and steady stream of thick black smoke from the stack.

In a best case scenario, even on the best commercial ships, change over to the emergency bus and regaining full control takes 2-5 minutes.

Emergency steering is local control from an aft steering station, and is hydraulic, and the pump is almost universally powered by....you guessed it, the emergency power buss. From there course changes are effected by manual changes at the console at the request of internal voice comms from the bridge to the emergency steering station. That takes time, and is subsequently cumbersome, slow, and only effective IF everything works AND everyone knows what to do.

This ship appears to already be in the wrong place well before the power issues.

 

[boatgeek]

It's also worth noting that these ships don't have a transmission. The main engine turns at a maximum of around 120 RPM and is directly connected to the shaft. To go into reverse, the engine has to be stopped, the propeller shaft has to slow down, a figurative lever has to be pulled to change the valve and injector timing, and the engine has to be restarted in reverse. All of that takes time.

Oh, and the rudder is less effective when the engine is in reverse.

I respectfully disagree on a couple of points.

I worked in the ship repair industry for a few years, specializing in cleaning and servicing and modernization of main power distribution onboard commercial vessels.

The emergency backup is an emergency diesel generator that kicks in, but it takes time and only powers certain things, many others have to be switched over manually.

Steering and steering control should be powered by the emergency generator, subject to all of the caveats above and below.

In the video, you can see the EDG start up, it's that puff and steady stream of thick black smoke from the stack.

I agree with the video presenter that the big puffs of black smoke are the main engine being restarted. The E-gen would be a much smaller puff of smoke.

In a best case scenario, even on the best commercial ships, change over to the emergency bus and regaining full control takes 2-5 minutes.

Nominally, power is back on in 45 seconds under the emergency generator. It definitely might take longer in practice, and of course it may take the bridge crew a little more time to get things sorted out while everything is going to hell.

This ship appears to already be in the wrong place well before the power issues.

I don't think that's true. Up until the power outage, they were squarely in the shipping lane.

 

[Banzai88]

After servicing dozens and dozens of USNS ships as wells as many commercial vessels, I have yet to see power actually up in 45 seconds. Maybe the EDG in 45 seconds, but the auto transfers and such, and the equipment online......no.

I know what spec is, and what the USCG mandates. Still never seen it happen, most landed in the 2-5 minute range to actually regain control, with many of the so called 'auto' stuff no-so-automatic, and that's US flagged vessels with crews trained for inspection.

 

[boatgeek]

After servicing dozens and dozens of USNS ships as wells as many commercial vessels, I have yet to see power actually up in 45 seconds. Maybe the EDG in 45 seconds, but the auto transfers and such, and the equipment online......no.

I know what spec is, and what the USCG mandates. Still never seen it happen, most landed in the 3-5 minute range, with many of the so called 'auto' stuff no-so-automatic, and that's US flagged vessels with crews trained for inspection.

I expect that the power comes back on in 45 seconds exactly once--in the pre-delivery tests while the factory techs are all over the place. After that, I'm not surprised if it takes longer. I have been trying to say nominally/is required to a lot, recognizing the distinction between theory and practice.

That said, the video above shows power going out at 05:24:30 UTC and lights coming back on at 05:25:31. While that may not have percolated down to the steering system, power to the lights was restored in 61 seconds.

 

[Banzai88]

I expect that the power comes back on in 45 seconds exactly once--in the pre-delivery tests while the factory techs are all over the place. After that, I'm not surprised if it takes longer. I have been trying to say nominally/is required to a lot, recognizing the distinction between theory and practice.

That said, the video above shows power going out at 05:24:30 UTC and lights coming back on at 05:25:31. While that may not have percolated down to the steering system, power to the lights was restored in 61 seconds.

Agreed. A tremendous amount of what we rebuilt/repaired/recertified and/or redesigned and installed was the buss tie breakers and auto transfer interlocks, as well as the EDGs themselves.

Each and every part has to work perfectly and in many cases timed properly for anything to come online other than the lights.

Failing that, it has to be done manually, and getting THAT right and properly coordinated probably only happens once as well!

 

[NTP2]

They would have an emergency generator on board. The rules on that are a little complicated, but the emergency genset and backup steering power should have been online within 45 seconds of a power failure.

I wonder if after this that gets smaller, in aircraft I believe power regain is almost instant just turn on the APU and everything from there is done for you so the pilot can focus on not crashing. I guess people thought that a ship would have time to get everything sorted so they didn’t crack down on that.

 

[boatgeek]

I wonder if after this that gets smaller, in aircraft I believe power regain is almost instant just turn on the APU and everything from there is done for you so the pilot can focus on not crashing. I guess people thought that a ship would have time to get everything sorted so they didn’t crack down on that.

The investigation will almost certainly point at maintenance issues on the ship. Fingers will get wagged, maybe inspections will get stepped up, and insurance will pay out a large sum of money. Being brutally honest, there weren't enough people killed in this accident to cause a change in the rules. It's very hard to get rules changed without death tolls around 25-50. Hundreds will usually get significant action in a year or three. In most cases, new rules also only apply to new ships, so it takes 15-20 years for a rules change to filter through the major carriers' fleets and another 15-20 for the second and third tier fleets.

The power should all come online automatically, but that doesn't mean it does. The marine environment is not friendly to electrics and electronics. Also, pilots have relatively hands-off systems because there's a crew of two on most airliners. A ship will have a crew of ~15-25, of whom at least 6-8 work in the engine department and can deal with some issues. That said, the chief engineer may not be on watch when leaving port at 0130 local time.

@Banzai88 can correct me if I'm wrong on anything, but the general procedure for getting the steering running again would be:
Start emergency genset and get stable power
Disconnect the emergency switchboard from the feeder from the main switchboard (breaker)
Connect the e-switchboard to the e-genset (another breaker)
If the steering HPU breaker tripped during the power outage, reset that (yet another breaker)
The steering HPU motor controller should come back online when power comes back on. If it didn't, push the button on the motor controller.
Repeat those last two steps for the steering control black box (may also include closing tripped breakers on transformers and lower-voltage panels since the steering control probably doesn't run on 480VAC)
Get the system to boot up and re-establish control
Check to see how far off centerline the rudder is
Now you get to start moving the rudder! By the way, it takes ~20 seconds for the rudder to go from centerline to hard over.

That's a lot of potential failure points. If anything didn't work, you need to send an engineer to the various switchboards and power panels to see if breakers are tripped when they shouldn't be. When you're 500 miles from shore, a few minutes to get this all running doesn't matter at all. When you're 2 minutes from hitting a bridge, it matters very much.

 

[wsume99]

I wonder if after this that gets smaller, in aircraft I believe power regain is almost instant just turn on the APU and everything from there is done for you so the pilot can focus on not crashing.

Aircraft typically have a significant amount of fault tolerance in their electrical power systems including battery backup of flight critical systems. For flight critical systems there would be no interruption of functionality if all power generating capacity went offline. The intent is for a loss of power generation to not cause a loss of control. Think of it like having your PC connected to an UPS - main power can go out and your PC is still humming along.

I know nothing about ship design and system architecture but for an aircraft to experience a similar condition - a complete loss of control due to electrical power failure - is a pretty rare event. Not saying it doesn't happen but there is a significant amount of effort put into designing a fault tolerant system architecture to provide flight critical power.

I'm surprised to learn that a ship could be without control (steering) power for more than a few seconds. I'm distinguishing between propulsive and control here recognizing the fall off in control authority when propulsive power is lost on a ship. Having diminished control is better than none. If there are humans involved in the emergency power process that is a huge red flag. I would think at the very minimum all crew should be at their stations and ready to respond when navigating in close proximity to obstacles.

 

[wsume99]

The investigation will almost certainly point at maintenance issues on the ship. Fingers will get wagged, maybe inspections will get stepped up, and insurance will pay out a large sum of money. Being brutally honest, there weren't enough people killed in this accident to cause a change in the rules. It's very hard to get rules changed without death tolls around 25-50. Hundreds will usually get significant action in a year or three. In most cases, new rules also only apply to new ships, so it takes 15-20 years for a rules change to filter through the major carriers' fleets and another 15-20 for the second and third tier fleets.

Agree with you on most of this however in this situation the other impacts of the incident may be severe enough to drive some updates to the regulations. Maybe I'm wrong but the cost of this accident will be measured in billions of dollars and 5+ years before the bridge is reopened. So I agree that a few lives won't get much attention but if you hit people in their pocketbook it certainly does. Think of all the lost revenue for MD while the port is out of commission. It may be something very inconsequential but I'll be shocked if there are not some changes to regulations as a result of this accident. Politicians are going to be looking for something to hang their hats on as a "fix".

 

[Banzai88]

The investigation will almost certainly point at maintenance issues on the ship. Fingers will get wagged, maybe inspections will get stepped up, and insurance will pay out a large sum of money. Being brutally honest, there weren't enough people killed in this accident to cause a change in the rules. It's very hard to get rules changed without death tolls around 25-50. Hundreds will usually get significant action in a year or three. In most cases, new rules also only apply to new ships, so it takes 15-20 years for a rules change to filter through the major carriers' fleets and another 15-20 for the second and third tier fleets.

The power should all come online automatically, but that doesn't mean it does. The marine environment is not friendly to electrics and electronics. Also, pilots have relatively hands-off systems because there's a crew of two on most airliners. A ship will have a crew of ~15-25, of whom at least 6-8 work in the engine department and can deal with some issues. That said, the chief engineer may not be on watch when leaving port at 0130 local time.

@Banzai88 can correct me if I'm wrong on anything, but the general procedure for getting the steering running again would be:
Start emergency genset and get stable power
Disconnect the emergency switchboard from the feeder from the main switchboard (breaker)
Connect the e-switchboard to the e-genset (another breaker)
If the steering HPU breaker tripped during the power outage, reset that (yet another breaker)
The steering HPU motor controller should come back online when power comes back on. If it didn't, push the button on the motor controller.
Repeat those last two steps for the steering control black box (may also include closing tripped breakers on transformers and lower-voltage panels since the steering control probably doesn't run on 480VAC)
Get the system to boot up and re-establish control
Check to see how far off centerline the rudder is
Now you get to start moving the rudder! By the way, it takes ~20 seconds for the rudder to go from centerline to hard over.

That's a lot of potential failure points. If anything didn't work, you need to send an engineer to the various switchboards and power panels to see if breakers are tripped when they shouldn't be. When you're 500 miles from shore, a few minutes to get this all running doesn't matter at all. When you're 2 minutes from hitting a bridge, it matters very much.

Pretty much spot on, with the addition that many of those breakers are 'auto transfer', meaning that when main power drops, they change position automatically. When main power is back on, they have to be manually switched back to their 'standby' position. ALL of that has to occur in a specific order so as not to cause damage by cross connecting high voltage/high current sources, and pay proper respect to phase rotation on the various phases (if applicable). Failing to do so often results in significant damage in terms of material condition and $$. Significant as in blowing apart or melting the internals of special order/manufacture $100K+ breakers.

Usually, almost none of that happens automatically OTHER than the EDG coming online (main power holds a dump valve CLOSED, and it's connected to high pressure air or a hydraulic accumulator that powers the EDG starter motor, so the EDG ALMOST always starts up first try. Almost. If it doesn't come on.....well, there are ways to get it started, often a battery back-up and electrical starter, but ALL of that is local manual control, and you hope and pray that the engineering team has been doing the PMs on the batteries AND the charger!) and SOME of the buss tie and transfer breakers opening/closing automatically (funny thing, it's the lights that almost always work. Not sure why, but people get really really REALLY hinky in the dark like the bowels of a ship, so the lights almost ALWAYS work even when nothing else does).

As you mention, the spike in power from the auto transfers happening to dead systems often ALSO drops the other downstream equipment breakers offline, and all of those have to be located and reset manually.

For aft steering, many that I've seen are controlled by a 'trick wheel' of about 3" diameter with something like 20+ turn per degree of actual rudder deflection. That's a LOT of mad spins to get the rudder hard over. A rudder that usually doesn't provide much steerage control under 3 knots indicated turns. Sometimes in the dark. And usually being given direction from the bridge over sound powered headphones. No big deal in the open ocean, not an ideal situation with 30 seconds to disaster

That being said, you are spot on about the marine environment being highly adversarial to those electricals and electronics. It takes a tremendous amount of cleaning and testing to keep it all working as it should, and none of that is cheap nor easy, and all of said maintenance takes time away from the primary revenue operations, as it requires that the ship be cold iron and isolated from shore power.

 

[Banzai88]

I wonder if after this that gets smaller, in aircraft I believe power regain is almost instant just turn on the APU and everything from there is done for you so the pilot can focus on not crashing. I guess people thought that a ship would have time to get everything sorted so they didn’t crack down on that.

I can only speak to .mil aircraft that I've worked on (F-14s, F-18s, and H-2s). They usually have an onboard battery that works through an inverter buss that auto transfers (used to be relay contactors, now it's solid state) power in an instant to maintain control systems off the battery/inverter while the APU (if installed) power ups and takes over. Change over still comes with a power hiccup, but critical flight systems, even .mil fly-by-wire take a licking and keep on ticking, so to speak.

Ships.....no so much. Ships inherently float, therefore a loss of power doesn't instantly pose an existential threat to existence like such a failure would to a flying aircraft, so there's a lot more leeway in response times.

 

[Tyeeking]

Agree with you on most of this however in this situation the other impacts of the incident may be severe enough to drive some updates to the regulations. Maybe I'm wrong but the cost of this accident will be measured in billions of dollars and 5+ years before the bridge is reopened. So I agree that a few lives won't get much attention but if you hit people in their pocketbook it certainly does. Think of all the lost revenue for MD while the port is out of commission. It may be something very inconsequential but I'll be shocked if there are not some changes to regulations as a result of this accident. Politicians are going to be looking for something to hang their hats on as a "fix".

It doesn’t have to be politicians forcing change. Loss increases risk for insurance companies which in turn changes underwriting. Insurance underwriters can very quickly institute changes that require annual inspection and third party certification of backup power systems as a condition of coverage.