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The Kerch Bridge Thread

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The Kerch Bridge Thread

Old 8th Oct 2022, 09:48
  #41 (permalink)  
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Originally Posted by ORAC
ROFL….



Vladimir Konstantinov, the head of Crimea's Russian-installed illegal "parliament", claimed that the damage was "insignificant", and the bridge would be repaired soon.
Perhaps he was concussed by the bang?

It will be done this century, but it won't be done by Russia. Can't imagine bridge builders not being opportunistically press ganged into a T-34.. or whatever is now left







Last edited by fdr; 8th Oct 2022 at 10:22.
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Old 8th Oct 2022, 09:49
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Originally Posted by dead_pan
One of the videos does appear to show burning materials landing on the bridge deck, possibly unexploded material from an improvised device?

I'm guessing the 1 or 2 spans which fell undamaged can be craned back up into place relatively quickly (assuming they are undamaged). The broken span will need to be replaced, which will take quite some time.

That said I wouldn't like to be a member of the crew tasked with repairing the bridge. The Ukes may take a leaf out of Russia's playbook and attempt a 'double-tap'
And where would you put the crane? or take the kinks out ?


I have no idea how Kerch bridge was built but I imagine something like this great timelapse video .
Measured on google earth , in that part of the bridge the spans seem to be 60 meters. Losing 180 meters of span is not 'insignificant' even if they happen to have 3 premade spans lying around somewhere.

Now given that kind of method it is interesting that that the section so close to the incline was broken , no doubt that makes reconstruction technically somewhat more difficult.

Last edited by Usertim; 8th Oct 2022 at 10:11.
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Old 8th Oct 2022, 09:50
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Originally Posted by petit plateau
I think there was something else, quite likely copper or aluminium to act as a penetrator. That likely is what also impacted the train of fuel rail cars.
There was an a lot of sparks in the explosion which supports this idea(?)
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Old 8th Oct 2022, 10:21
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Enough speculation gents, it's obvious that Russia is copying Ukraine's disinformation campaign. Just as the Ukrainians blew up their own civic buildings and apartment blocks and blamed it on the Russians who were only trying to protect their UKR-based countrymen, so Russia has blown up its own bridge and probably the two TU22 bombers the other day. You can't fool me, Comrade Putin.
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Old 8th Oct 2022, 11:03
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Originally Posted by Usertim
And where would you put the crane? or take the kinks out ?

https://twitter.com/Osinttechnical/s...111680/photo/1

I have no idea how Kerch bridge was built but I imagine something like this great timelapse video . https://youtu.be/vKGYs71N72c
Measured on google earth , in that part of the bridge the spans seem to be 60 meters. Losing 180 meters of span is not 'insignificant' even if they happen to have 3 premade spans lying around somewhere.

Now given that kind of method it is interesting that that the section so close to the incline was broken , no doubt that makes reconstruction technically somewhat more difficult.
Yes they are doing something similar just down the road from me at present. (I'm not currently in UK ) They cast them on a piece of road and pre-tension the cable reinforcements as the concrete cures. No idea what the setting time is, they do it months in advance here as a down-time job. Then in this case they are lifting using high cranes rather than that extending hoist widget you've proposed which is generally used on TGV rail builds.

I think they used barge-mounted cranes for the original Kerch build (I vaguely remember seeing some photos), but winter is coming on. They do have some jack-ups in the area and they are less weather dependent. But the simplest is to work from the existing remaining structure - all the piers are still in place. The adjacent roadway is in place. So just (!) place cranes onto the existing piers on the adjacent roadway. Then lift. After dumping the debris into the water. They will be taking all sorts of safety short cuts for a repair and for usage. Don't misunderstand me - I would like it to be very difficult, go disastrosly wrong, and not to restore the usability any time soon, and that the conflict will be over before then. I would also like Ukraine to get to within HIMARs range soon. But in the meantime the good news is that any repair efforts will likely badly affect the other carriageway. Only possible way around it all is just to float a load of barges into place with a floating roadbed in the gaps as a interim lash-up - hopefully weather/tide/current make that non-viable this winter.
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Old 8th Oct 2022, 11:04
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Originally Posted by NutLoose
That secondary fire seen off the bridge.


A bit of a Garth Brooks moment;

Burning bridges
One by one
What I'm doing
Can't be undone
And I'm always hoping someday
I'm gonna stop this running round
But every time the chance comes up
Another bridge goes down

JAS
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Old 8th Oct 2022, 11:17
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Smile

Originally Posted by Beamr
Russian state media claims now that it was a TRUCK that was blown on the bridge and causing the span to collapse.

also, Russian officials are working to set up a ferry crossing over the Kerch strait.

https://rg.ru/2022/10/08/reg-ufo/nak...tomobilia.html
What a beautiful sunrise.

Any guess if the rail line is still useable?
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Old 8th Oct 2022, 11:23
  #48 (permalink)  
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I would say the rail bridge is firked, that amount of heat over a sustained period would expand the rebar cracking the concrete, they had an artic fire under a motorway bridge years ago up Nr where I come from and that is exactly what happened, they had to replace the spans. Plus the rails are probably softened and buckled.

Which bridge carrry’s the Crimean water supply, because if that’s out and they recapture the canal then Crimea has more woes.
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Old 8th Oct 2022, 11:35
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Originally Posted by NutLoose
The boat? You decide.

Looked at the video again and have to say: I'm pretty sure there is a boat arriving fast just in that second just in that place and just when it arrives - kaboom.
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Old 8th Oct 2022, 11:37
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Looking at this it appears it’s not going to be a quick lift and plonk back into place, the last picture indicates Putin was looking ahead work wise.

https://www.rferl.org/a/aerial-image.../28675651.html

A good read on the construction etc, they dropped a rail section during construction and replaced it in a couple of months, but that is smaller and all the barges, cranes, and construction facilities were in place.

https://ege76.ru/en/tongue-twisters/...-osnovnye.html


..

Last edited by NutLoose; 8th Oct 2022 at 11:51.
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Old 8th Oct 2022, 12:03
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Usual caveats:

"Trains expected to be travelling ONCE AGAIN on Crimean Bridge by 20:00 this evening, following bridge explosion (https://t.me/IntelRepublic/6455) - Russian Transport Ministry."
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Old 8th Oct 2022, 12:33
  #52 (permalink)  
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Originally Posted by Wokkafans
Usual caveats:
"Trains expected to be travelling ONCE AGAIN on Crimean Bridge by 20:00 this evening, following bridge explosion (https://t.me/IntelRepublic/6455) - Russian Transport Ministry."
Now that's what you call fast service. Do you get fries with that too?
Structural engineers were checking the structure while it was hot enough to cook their Borsch? Efficient! No cores, no tensile load tests, just another train, driven by a hero of the Soviet Union Russia.
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Old 8th Oct 2022, 12:40
  #53 (permalink)  
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I think pushing would be preferred to pulling the train……

I feel shades of Remagen coming on…
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Old 8th Oct 2022, 12:57
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Not that it matters much but in the videos I was sent the train heading towards Crimea was running at not much more than walking pace. Very little blast/frag in this explosion*, little mid-sized rubble spread and the light debris was taken away by the breeze. The whole scene looked swept clean in the immediate aftermath.

Usually best to ignore apparent blast positions on video (due to frame rate, compression et al) but at the start of the event there is very little damage to superficial / tertiary structure (lampposts etc) or even on things normally cast aside by explosions much smaller than this (eg at least 1x car and 1 x truck that would have normally exited the stage (...pursued by a bear?).

So with the evidence (as of yet) we can probably put aside impact blast, airburst, truck bomb or span demolition charges. Even direct demolition of piers looks doubtful. So what we are left with is a scene that looks like ground heave alone, albeit with a bit of water above it. On one of the videos the seat of the explosion looks to be located adjacent to the northern side of the road deck. It was truly significant charge with deep and heavy debris breaching the surface and making it as far as to land on the collapsing span, followed by the deluge of water. It had enough energy to lift some above-surface structural items with it (inc the reinforced piers) and also caused numerous small self-extinguishing or doused steel fires on the immediate surrounding area.

The effect on the sub-surface structures and underlying bed will have been significant and well-beyond my knowledge (yes, I'm a weapons effect specialist but at this level we would be leaning almost entirely on the scientific staff). Pretty sure their first phrase would be '...a complex interaction that may be difficult to model...'.

The effects on the train are very similar to the scene close to the blast. Little or no effect on the train, no apparent derailing, tipping, decoupling or toppling. Very little medium sized debris made it up there beyond that carried by the water spray. If not for the cargo on the train it would almost be a non-event to the rail element (well, apart from fleshy things not liking blast waves) but the footings would need to looked at with a specialist team. Unfortunately high-speed burning metal meeting big tin-cans of POL is a chemistry event. Given the traverse wind and sequential cooking-off of the tanks spells misery for the the rail bridge structure. The blow-torching of steel both changes its material properties for the worst and makes it sag, stretch, expand at points various. The concrete will also have immediate spalling plus a whole host of micro-fissures that will allow a visually 'ok' bit of concrete fail very quickly due to the maritime environment.

An interesting one for sure and I hope more info is revealed so a more credible effort can be made to understand it than my first attempt above.

(* I acknowledge that there appears to be a signature event in at least one of the blast videos - this may or may not be the case but best not to comment further on such things.)
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Old 8th Oct 2022, 13:03
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To use shaped charges as several people have suggested, they need to be in direct contact with the metal you are are trying to cut. Placing a charge even a couple of inches away will not cut a train rail.
Placing a boat load of explosives under the bridge even if it is just 20 feet between boat and span will loose a great deal of its shock wave effect (Which is what you use to destroy a fixed structure).
A lorry load of explosives would be the same issue, the bast would likely result in a crater roughly the size of the vehicle and would not be likely to create enough of a shock wave that brings down several non adjacent spans.

This could be an inside Rusk escalation with charges attached to the joints of one of the bridge junctions, including an accelerant / vaporiser.
The second option is a very large air delivery munition, by choosing a lower span, there is more opportunity for secondary shockwave reflecting back off the sea. I wonder if the lower height of the piers means. less flex in the sea creating a more rigid structure than targeting a higher level pier.
Is a long time since I did dems but we always used to look a channelling the shockwave.
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Old 8th Oct 2022, 13:07
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Originally Posted by Just This Once...

(* I acknowledge that there appears to be a signature event in at least one of the blast videos - this may or may not be the case but best not to comment further on such things.)
But that signature looks pretty conclusive does it not ?
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Old 8th Oct 2022, 13:10
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To quote Apocalypse now: "Like this bridge, we build it every night Charlie blows it right back up again. Just so the Generals can say the road's open."


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Old 8th Oct 2022, 14:08
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Originally Posted by Just This Once...
Not that it matters much but in the videos I was sent the train heading towards Crimea was running at not much more than walking pace. Very little blast/frag in this explosion*, little mid-sized rubble spread and the light debris was taken away by the breeze. The whole scene looked swept clean in the immediate aftermath.

Usually best to ignore apparent blast positions on video (due to frame rate, compression et al) but at the start of the event there is very little damage to superficial / tertiary structure (lampposts etc) or even on things normally cast aside by explosions much smaller than this (eg at least 1x car and 1 x truck that would have normally exited the stage (...pursued by a bear?).

So with the evidence (as of yet) we can probably put aside impact blast, airburst, truck bomb or span demolition charges. Even direct demolition of piers looks doubtful. So what we are left with is a scene that looks like ground heave alone, albeit with a bit of water above it. On one of the videos the seat of the explosion looks to be located adjacent to the northern side of the road deck. It was truly significant charge with deep and heavy debris breaching the surface and making it as far as to land on the collapsing span, followed by the deluge of water. It had enough energy to lift some above-surface structural items with it (inc the reinforced piers) and also caused numerous small self-extinguishing or doused steel fires on the immediate surrounding area.

The effect on the sub-surface structures and underlying bed will have been significant and well-beyond my knowledge (yes, I'm a weapons effect specialist but at this level we would be leaning almost entirely on the scientific staff). Pretty sure their first phrase would be '...a complex interaction that may be difficult to model...'.

The effects on the train are very similar to the scene close to the blast. Little or no effect on the train, no apparent derailing, tipping, decoupling or toppling. Very little medium sized debris made it up there beyond that carried by the water spray. If not for the cargo on the train it would almost be a non-event to the rail element (well, apart from fleshy things not liking blast waves) but the footings would need to looked at with a specialist team. Unfortunately high-speed burning metal meeting big tin-cans of POL is a chemistry event. Given the traverse wind and sequential cooking-off of the tanks spells misery for the the rail bridge structure. The blow-torching of steel both changes its material properties for the worst and makes it sag, stretch, expand at points various. The concrete will also have immediate spalling plus a whole host of micro-fissures that will allow a visually 'ok' bit of concrete fail very quickly due to the maritime environment.

An interesting one for sure and I hope more info is revealed so a more credible effort can be made to understand it than my first attempt above.

(* I acknowledge that there appears to be a signature event in at least one of the blast videos - this may or may not be the case but best not to comment further on such things.)
Prior to building, there was considerable doubt that the foundations would be stable due to mud volcanoes etc in this region. Could there be an attempt to undermine the stability of the structure?
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Old 8th Oct 2022, 14:58
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Originally Posted by Spunky Monkey
To use shaped charges as several people have suggested, they need to be in direct contact with the metal you are are trying to cut. Placing a charge even a couple of inches away will not cut a train rail.
Placing a boat load of explosives under the bridge even if it is just 20 feet between boat and span will loose a great deal of its shock wave effect (Which is what you use to destroy a fixed structure).
A lorry load of explosives would be the same issue, the bast would likely result in a crater roughly the size of the vehicle and would not be likely to create enough of a shock wave that brings down several non adjacent spans.

This could be an inside Rusk escalation with charges attached to the joints of one of the bridge junctions, including an accelerant / vaporiser.
The second option is a very large air delivery munition, by choosing a lower span, there is more opportunity for secondary shockwave reflecting back off the sea. I wonder if the lower height of the piers means. less flex in the sea creating a more rigid structure than targeting a higher level pier.
Is a long time since I did dems but we always used to look a channelling the shockwave.
Shaped charges most assuredly must NOT be in direct contact with the target. They require a standoff distance related to a multiple of the width of the charge as per the individual design. In the case of a custom-made charge built into a boat it could be a vary wide device ndeed - say a metre. A 5 times standoff distance would be at peak effitiveness at 5m, about the height of the bridge I'd guess, and such a charge laid along a boat is in the perfect alignment to sever a structure like a bridge from edge to edge.
In any case a sufficiently large in a boat under a bridge is simply going to lift it up in the air and let it drop or with enough brisance simply shatter the concrete. The blast pressure will be 'loosed' (sic) in all directions, but the water will tend to reflect much of it upwards where you want it.That'd do the job too.
If you imagine a ton or more of explosive is defeated by a 20ft airgap or only leaves a 'crater' the size of a vehicle you are way, way off the mark.
The lack of obvious scarring suggests a blast from below which had the added effect of projecting debris upwards to puncture the tank-cars.
No way was this air delivered or the defences would have lit up like Novemner 5th.
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Old 8th Oct 2022, 15:04
  #60 (permalink)  
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Russians allowing 10 cars every 30 minutes over remaking lane of the Kerch bridge.

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