dustie Loc: Nose to the grindstone

A big enough barrier of some kind can do some stopping.

How much is going to be big enough is going to depend on many things, and a simple concrete pylon design (which you originally suggested) is going to have to be a massive pylon if it's going to catch, hold and contain the massive energy that is present in even a low speed impact.

How massive are those pylons going to have to be if they are expected to catch, hold and contain a vessel that hits at 10, 12, 14, or more knots instead of down around 7.5 - 8 knots?

At what point do engineers and lawmakers and public agree there is no possible way a barrier is too small to prevent the potential for damage in an as-yet-unseen incident of monstrous proportions?
From which direction is there never going to be any possible chance a bridge pylon could be contacted? What happens if a bumper/pylon is not built to completely surround the bridge support, then a vessel somehow gets in and hits it on an unprotected side?

The reinforced concrete below waterline holding the Dali, is far more massive than the vertical members that were above water.
If it was to be "copied" as a design for pylons/bumpers that could not be breached, it would have to be many times larger above water than what those vertical members were. The taller they have to be to reach from bedrock to expected height of contact above water, the more proportionately massive they will have to be so they can hopefully be strong enough to prevent any release of energy from breaking through.

At what point of time, materials, expense, waterway obstruction, can it be agreed the bumpers/pylons are big enough to never be not big enough?

pendennis

Most construction has to be built "good enough". An engineer and/or designer would go nuts trying to thing of all the permutations and conditions which could make any structure invulnerable.

The Dali had two pilots on board, but even they couldn't predict that she would lose power, go to auxiliary, and from the looks of the film, lose auxiliary power also. And who could've predicted that she would lose power at that point in the river?

One of the talking heads made a big deal of the emergency anchor, and why it didn't stop the ship. Most folks don't have any idea of the energy generated by a ship that size, and of whatever speed she was running. Dropping the emergency anchor would be akin to dropping a fishing line overboard and hoping the hook would catch onto a clump of weeds.

I spent a number of years in the Navy Reserve, and on my first cruise on a WWII Sumner Class DD. While at sea, the captain would order drills such as losing power, then losing aux. power. Didn't understand at first, but it was an excellent drill.

dustie Loc: Nose to the grindstone

Yes. Today, some reports are attempting to correct yesterday's reporting, saying one of the pilots is a trainee, an apprentice, likely not tasked with control responsibilities. The other pilot has quite a few years experience in that harbor, and reportedly, in preparation for leaving the dock, found nothing amiss with the ship within his sphere of responsibilities.
____________________

It's probably difficult for those who have never been involved with anything larger than a Chevy Suburban, if even that large, to have a grasp of the exponential increase in momentum forces of machinery that is magnitudes greater in weight and size than the boulevard cruisers.
That's a different world almost, even in land-based machinery, where there are different surface friction forces that affect movement/motion of the machinery.

Then, the water-borne craft have different surface friction parameters, plus the water that supports the vessel also exerts pressures to move the vessel, so that's added to the control input needs of the operators and machinery.

PhotogHobbyist Loc: Bradford, PA

I think we have been living with the possibility that bridges will be struck by watercraft, shaken down by hurricanes, or damaged in many other ways by nature and man.

SteveR Loc: Michigan

And yet the ship stopped right on the spot of impact. If things were as dire as you insist, why didn't it just keep moving THROUGH the bridge onto the other side of it? Solid rock has a way of stopping even the stoutest of vessels.

dustie Loc: Nose to the grindstone

Going by aerial photos posted of the scene, it appears the Dali moved forward about the width of the four lane bridge after making contact. That is how much force was still being applied by that mass at about a fast jogging speed/slow running speed. What kind of barrier should be erected so that there is no chance of bridge damage from a heavy mass of that kind at a higher speed?

The mass of the below water bridge structure was able to catch that.......maybe. The draft, or draught if you prefer, of the Dali is reported at 49+ feet. It's reported the bottom where much of the bridge wreckage is lying, is around 50 feet.
Over there, out to the side of the main channel, outside the bouy markers, is the keel of that ship on the bottom, in shallower water? Did that also exert stopping force against its forward movement, so that the underwater bridge structure did not bear all the pressure that could have been applied, had the bottom been much, much deeper than the draft depth of the vessel?
Is the ship in contact with the bottom now, helping to keep it stable where it is?
All questions that hopefully can be answered in public reports as the investigation moves forward.

My points:
•• this was a very high mass, low speed incident, and is it yet known that the ground, bottom of the harbor, did not have any part in stopping the forward movement of that ship?

•• how much mass/size/rigidity of bumper/pylon/dolphin/barrier/protector is going to be required to ensure there will never be any instance in which any impact will be too much for the capability of the baririer.

•• where do engineers, regulators, financiers, builders, upset public, finally agree to draw the line that there is enough barrier to prevent any remote possibility of ever having anything break through, ride over, disintegrate into multiple battering rams and pummel the bridge support from different moment force points and still wreck the bridge support, instead of holding together in one single, slow ram as happened this time?

•• How far out from the bridge support should the outside edge of the barrier be located, so that any large, massive vessel whose farthest forward upper edge is many yards forward of its hull at waterline, has less than zero chance of ever contacting the bridge support, in any scale of disaster?

dustie Loc: Nose to the grindstone

EDIT
On Tuesday, the vesselfinder.com site had the draft depth of the Dali listed at 49' 4". Now that site has that information and quite a lot of other items in the listing that were visible on Tuesday, locked, unavailable to general public, apparently.
Wikipedia still shows the draft depth being 49' 4".

Wondering if there are any other sites listing specifications, I found that seamanmemories.com lists the draft at about 40', and there is another listing it 40', but I've forgotten which site it is.

So, I don't know, maybe, maybe not, there was enough clearance it did not drag bottom, and is not touching bottom now.
I'm sure the questions will outpace any publicly available answers.

Schoee Loc: Europe

Perhaps the tugs need to stay with the big ships until clear of all bridges.

jerryc41 Loc: Catskill Mts of NY

You can bet that the replacement bridge will have them. That's exactly what happened after a ship destroyed another bridge. That should be a national requirement for bridges. I'd prefer an island barrier to dophins, though. When a ship weighing over 200,000 tons is gliding through the water, it takes something solid to stop it. If you really want to protect bridge supports, you have to really protect them. In the pictures below, the only one I would recommend is the island, only larger.

"Do or do not. There is no try." Yoda

https://en.wikipedia.org/wiki/Dolphin_(structure)

GregS Loc: Central Illinois, USA

Same thing happened to the newly constructed mile long bridge from Pensacola, FL to Gulf Breeze, FL. Pensacola was told not to worry about a tropical storm. However, it turned into a level one hurricane over night. No one was prepared for that! A group of barges tied up for the 'tropical storm' broke loose and took out the new bridge.
Rather than a mile ride to Gulf Breeze, it now took over 2 hours to go around.
No protection around the base of the bridge. Will have to check to see if they corrected this.

agillot

This bridge was like a chain , you cut one link , the whole thing collapse .Just a different way to design a bridge , not the best .On the other hand , cranes should have been there to clear one path for ships to move thru .

Canisdirus

The ship lost power completely...because of...dirty fuel.

It's an ongoing racket...here at home. They fill up and get 80% good fuel and then they mix in 20% of garbage fuel...and charge the same.

Has zero to do with the crew...the ship probably choked when they dropped their rpm's...and they could not get it started again.

srt101fan

Oh, good! We have another expert answer. No need to waste money and time on any further investigations....

jerryc41 Loc: Catskill Mts of NY

srt101fan

Of course that could have been a cause or contributing cause.

I just object to the dogmatic way some people rush to judgment. It's sadly emblematic of so much of our discourse on vitally important national issues.