Baltimore Bridge collapse after ship collision 125

[Tomfh]

https://amp.9news.com.au/article/b73620ea-64ab-4253-8cb0-37102418fcab

 

[phamENG]

Regarding fenders - I've never designed them for a bridge, but I've done several for mooring facilities.

Timber dolphins or timber fender systems use energy dissipation in the wood. You essentially derive a spring constant from the piles and then determine the amount of energy it can store. Haven't done one in a while and my marine facility design references are in a box at the moment.

On larger facilities for ships, we usually use rubber fenders. The manufacturers publish energy absorption graphs for various temperatures and impact velocities. I would include in my design documentation a maximum pressure on the fender plate along with a maximum considered velocity. The facility owner would then include that information in communication with the ship's master and they'd work out the details. One job had a permanent barge moored against the fenders to 'even out' a oddly shaped wharf (facility originally built in the late 1800s, updated in the 1940s, and then they found ships in the 80s didn't fit anymore). The barge was ancient so we had to consult with a naval architect to get allowable hull contact pressures to make sure its hull didn't become part of the energy absorption equation for normal mooring operations.

 

[Sym P. le]

StreamTime Live - Youtube Port of Baltimore

Web cam location appears to be at Riviera Beach.

 

[dik]

I suspect a ferry is just a fraction of the mass.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[SkipVought]

John, you don't want to go there.

Skip,
[sub]
Just traded in my OLD subtlety...
for a NUance![/sub]

 

[zeusfaber]

The dolphin then rebounded and the ferry hit the dolphin on the other side a glancing blow.

A big bounce suggests a lack of energy absorption.

As to anchors: I started a thread here on Tuesday about a cruise ship that suffered a TLF and came perilously close to catastrophe. In that case, they were doing 4 kt and had time to let a couple of anchors go. All that did was to rip the flukes off one (probably both actually, but they never got the other one back) of the anchors and complicate the task of extricating the ship from a nasty corner once propulsion was restored.

A.

 

[Jedidad]

For a large ship like this that doesn't have azipods and bow thrusters, to be allowed to traverse through inland channels with bridges etc. and not under control of tugboats. Someone some where is and was not using much logic.

She has a 4,000hp bow thruster.

https://en.wikipedia.org/wiki/MV_Dali

 

[TugboatEng]

There is a reason it is going around the internet. Someone is spreading it.

 

[ThomasH]

First a very short comment regarding the cost. I saw the statement President Biden made that the federal government will pay. As I understood it, the reconstruction needs to start fast because Baltimore can't wait for the legal issues to finish. Therefore, the federal government will pay initially.

Regarding the crash, something that is probably more interesting in this forum. I was actually involved in designing a crash barrier for a ship a few years ago. The size of that ship was significantly smaller.

What we are dealing with here is kinetic energy, and lots of it, just to test some approximate numbers. Say 160 000 tons at 7 kts (3.6m/s). If that is the weight of the ship the moving mass will actually be larger because the water close to the hull will move with the hull. But I skip that for now.

Wk= 160 000 tonne * (3.6 m/s)^2 * 0.5 = 1.0 G Joule = 1.0 GN m

To stop this, we need something very strong and very ductile. Let's assume that we can go directly to plastic deformation. Something that can withstand 500 Mega Newtons for 2 meters would work. Part of the energy will of course be absorbed by the ship itself. Even if I assume that the ship and the barrier will "share" the energy 50/50 the numbers are bad.

Either a longer stopping distance is required or, probably better, don't stop the ship, "only" change its direction.

But I have a question regarding this. I am well aware of that this bridge is not new. But if it was new, would it be acceptable that the fairly limited damage we see leads to a total collapse?

 

[MTNClimber]

But if it was new, would it be acceptable that the fairly limited damage we see leads to a total collapse?

To me, it appears the answer is no. With insurance claim estimates in the $2-4B range and the cost of a new bridge being around $600M, you have all the reason to build a protection system to stop or deflect a ship from demolishing the bridge.

 

[LionelHutz]

ThomasH - I'd expect any new structure would have better protection. A bigger island and/or more dolphins around the bridge piers for sure. But, yes if a bridge support managed to sustain that much damage then I'd fully expect the bridge to collapse.

 

[AZPete]

If you can't accommodate a direct impact with whatever is floating/steaming down the river, then you apply failsafes in whatever form necessary. Could be barriers, redundant structure, etc.

 

[Sym P. le]

maritime-executive.com - NTSB Releases "Black Box" Timeline of Baltimore Bridge Strike

Collision segment of StreamTime footage from their Youtube page at 720p.

 

[Alistair_Heaton]

Hats off to the bridge shutting down so fast.

 

[hokie66]

The cost of the bridge is one thing, the value is quite another, and exceeds the cost by a wide margin.

 

[Alistair_Heaton]

had this discussion a month ago about diversion choices to a single runway hub.

Shut everything down for 12 hours or go and screw Ryan Air up for 12 hours...

 

[ThomasH]

ThomasH - I'd expect any new structure would have better protection. A bigger island and/or more dolphins around the bridge piers for sure. But, yes if a bridge support managed to sustain that much damage then I'd fully expect the bridge to collapse.

I agree with you. I don't know in detail how US codes have evolved over time but I know that other codes have changed regarding things like redundancy.

On the other hand, to be able to withstand the impact from a ship of this size may not be reasonable. There is also the probability for an accident to actually happen. It may seem a bit cynical, but risk analysis has to weigh the cost vs the benefit.

The best thing now I think is to try to learn from this and try to prevent it from happening again. But anybody who thinks this ship would have been easy to stop, I don't share that idea.

Hats off to the bridge shutting down so fast.

Couldn't agree more.

 

[hokie66]

The new bridge needs to be built with a longer main span, so that the supports are well clear of the channel. The span is/was 1200 feet. By comparison, the much older (1952) Chesapeake Bay Bridge downstream at Annapolis has a main span of 1600 feet.

 

[JohnRBaker]

Yes, Hokie, that would seem to be a reasonable criteria for whatever type of replacement structure is finally approved to replace the Francis Scott Key bridge, which I assume will carry the same name (after all, he was associated with Baltimore, but then so was Edger Allan Poe).

John R. Baker, P.E. (ret)
Irvine, CA
Siemens PLM:

The secret of life is not finding someone to live with
It's finding someone you can't live without

 

[charliealphabravo]

The bridge and pier, as un-intended as it was for that purpose, stopped the ship. It follows that there is really no reason and no excuse for this tragedy considering our understanding of infrastructure protection. This is an event that simply cannot be allowed to happen.

A simple risk matrix would have put this bridge at the top of the list for additional protection against accident or sabotage.

 

[3DDave]

Wait until that risk matrix includes large commercial passenger jets.