Bridge Collapse in Dresden 1

[Retrograde]

The partial collapse of the Carola Bridge disrupted major traffic artery in Dresden and left the city without hot water.

A bridge carrying a tram line partially collapsed in the German city of Dresden. The Carola Bridge is one of the four bridges crossing the Elbe River.

The emergency closure of the 100-metre-long bridge resulted in severe disruption of the city's traffic, including the tram system and boat traffic. The bridge is a major travel route between Dresden's Old Town and New Town, and is used by motorists, pedestrians and cyclists.

https://www.euronews.com/my-europe/2024/09/12/major-bridge-partially-collapses-into-river-in-dresden

 

[hokie66]

To me, and just based on the photos in that article, it looks like the tram/cycle/walking part of the bridge was at least partly hung off the side of the motorway bridge. Maybe an extension of the original bridge?

 

[human909]

WOW. That doesn't look that old and Germany isn't exactly a nation known for engineering underperformance.

I'll throw my uninformed, speculative hat into the ring and disagee with hokie66. The bridge doesn't seem to be hung off the motorway bridge. I haven't dug up the time-line beyond being built in the late 60s, but the configuration would suggest that the tramline was built at the same time as the motorway.

Another uninformed, speculative guess... I think that this is surely a reinforcing failure presumably post tensioned cables from corrosion.

**This is a wild and uninformed guess but given the type of construction and the timing of failure that is my thoughts.

 

[MintJulep]

Germany isn't exactly a nation known for engineering underperformance.

Don't forget that Dresden was part of East Germany prior to the fall of the wall.

This bridge was built during 1967 - 1971, so designed and constructed to whatever Soviet era standards were in effect then.

When it was designed, the trams in Dresden looked like this:

Now they look like this:

Road traffic likely also got heaver and more over the years.

 

[Retrograde]

This photo suggests there was some connection between the tram bridge and the motorway bridge.

 

[Tomfh]

Another uninformed, speculative guess... I think that this is surely a reinforcing failure presumably post tensioned cables from corrosion.

The way that joint has opened up you'd think something has snapped. Corrosion a definite contender. Could be fretting fatigue of the cables too. The cables rubbing each time a tram goes over.

 

[LittleInch]

This is actually three bridges side by side, with some small connections between them.

It does appear to have been built in segments

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[LittleInch]

This is a better view.

Also the next section is now about to collapse by the look of it.

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[LittleInch]

Looks like this is a prestressed concrete box girder with a very slendr arch.

"The current bridge was built between 1967 and 1971 by VEB Brückenbau Dresden and has since formed an important north-south link in Dresden's road network, connecting Albertstraße in the north with St. Petersburger Straße in the south. It has four lanes for motorized traffic and a separate track for the streetcar. In addition to the lanes, there are also footpaths and cycle paths on both sides of the bridge.<br><br>The Carola Bridge is 32 meters wide and consists of three superstructures (bridge span A to C), which are designed as prestressed concrete box girder bridges with Gerber girders. The spans vary and reach 44 meters in the southern edge span and 58 meters in the first inner span. The bridge spans the Elbe with spans of 120 meters and 95 meters, while the northern end span has a span of 58 meters. The Carola Bridge was the prestressed concrete bridge with the largest span in the GDR and has a minimum clearance height of 6.61 meters."

I know this is at a joint but there doesn't look to be a whole lot of rebar in there. They had refurbished bridges A & B and this was C, planned for the following year. Too late it seems.

...

Looks like they widened the bridge at some point for pedestrian and cycle lanes.

https://onlinelibrary.wiley.com/doi/full/10.1002/cend.202100046

That looks like bridge A to be fair.





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[centondollar]

Gerber beams are non-redundant and a poor choice for bridge building. I wouldn't expect a lot of rebar in the so-called internal hinges which are designed for zero moment transfer by employing e.g., corbels or by terminating flexural reinforcement.

 

[IRstuff]

This part of the image looks odd. It looks like the part that fell would be applying tension to the part that broke, but it looks like concrete, with odd looking rebar.

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[Sym P. le]

Essentially three spans on a common substructure?

From the photo, the structure appears to sag at the connection to the left of the tram. This was likely a notable issue with a rollercoaster effect. I'm surprised it wasn't identified earlier. Beefing up the pier cap was a partial solution to a bigger problem.

From Google Maps, significant improvements were recently carried out on the center span.

I note that Mint's Wikipedia sourced image is dated March 2023. I don't see a corresponding dip on Street View which is dated "a year ago."

On Google Street View, there is a distinct dip in the pedestrian lamps. The lamp partially obscured by the tram power pole is definitely low. There is also a corresponding dip in the structure beneath the fencing near the right side of the image. These irregularities don't appear to be stitching artifacts from the panorama.

From a German source, ZDFheute, it sounds like they are quickly demolishing the entire structure before anticipated weekend flooding.

Edit: On closer translation, the damaged sections.

Also, through Google translation, "The collapse of the Carola Bridge in Dresden has sparked a discussion about the backlog of bridge repairs. Experts estimate that many of the 130,000 bridges need to be replaced."

Regarding the renovations, "The renovation of the middle bridge section was fully completed with the installation of the railings at the beginning of June 2024. The construction costs amounted to around 4.1 million euros. The renovation of the third bridge section, the eastern one, was already completed in June 2021."

They can now put the 4 million Euros of next years savings toward a more permanent solution.

 

[Sym P. le]

Beam cross-section, GettyImages:

Though it's a little more complicated than that:

 

[FacEngrPE]

The key between the beams explains the strangely distorted rebar IRstuff (Aerospace) noted. To me it looks like the key was overloaded to the point where the concrete crumbled, leaving the distorted rebar behind.

Before

After
The key was not intended to hold the bridge up, it's likely good that it behaved like a fuse, or the load might have pulled the the center span down.

 

[hokie66]

I doubt those are 'before' and 'after' shots of the same thing. But how this structure was supposed to work is all confusing to me.

 

[Sym P. le]

The archive image is the A-B link whereas the damaged link is B-C. It looks like a different design but with the same purpose. Maybe a flexible link to accomodate varying deflections and vibrations between the independant spans.

 

[Alistair_Heaton]

I seem to remember the TV tower in Dresden is quite spectacular.

They used to have a restaurant at the top of it in USSR days.

Lord knows what state that's in under the surface.

 

[Sym P. le]

The satellite confirms my suspicions ... and a corresponding uplift at the opposite end of the structure.

Casey Jones - Youtube

 

[FacEngrPE]

thread1088-455633 was suggested with respect to the The Genoa Bridge Collapse 2018.
European Space Agency information about InSAR

 

[Sym P. le]

Technology is great. In this instance however, the distress was plainly visible with the unaided eye and likely felt by tram passengers on every crossing.