Bridge collapse

[Adrian R2Participant @adrianr2]

£1.5 million, not £15 million. Still a lot of beans to you and me.

That AI summary contains no useful info with regard to failure mode so I’m sticking with my diagnosis of a bound up top pivot. The design relied on the mass of the bridge being correctly distributed to keep the teeth engaged so a bit of unexpected rotational torque would upset that.

I am not a civil or structural engineer.

 

[Michael GilliganParticipant @michaelgilligan61133]

I think the Prior Context line nicely supports your thinking, Adrian

MichaelG,

[Adrian R2Participant @adrianr2]

A second possibility, the hydraulics dropped faster than expected and then stopped suddenly either by themselves or on command, inertia of the descending span took over and again altered effective mass distribution and lifted the teeth of the rack.

Enough unqualified speculation, I shall await the official report.

[JAParticipant @ja]

Inspection report says that the bridge failed due to a lack of maintenance and severe corrosion. Part of the problem was the sealing between the wooden walkway planking had perished so allowing water to collect in the structure.

The bridge is going to be dismantled and removed.

Now if it had a roof……

JA

[old martParticipant @oldmart]

Last night the remains collapsed into the water, see the BBC news.

[duncan webster 1Participant @duncanwebster1]

https://www.bbc.co.uk/news/articles/cjr4y73qd7p9o

[old martParticipant @oldmart]

The poor taxpayer will have to cough up even more now, it’s about time that architects were made to give a 100 year guarantee on their designs.

[JAParticipant @ja]

I think it is being taken to the Albian Dry Dock, one of the last true businesses on the Floating Harbour. I believe that their waiting list can be quite long. So, I guess, Bristolians will have stump a lot bit more money to get their favourite bridge back quickly.

The design life of another great local bridge, the First Severn Crossing (the old M4 bridge), was 25 years. It is now slowly dying (how do you replace the catenary cables?).

JA

[Mark RandParticipant @markrand96270]

Meanwhile, the Clifton Suspension bridge has been going for a bit over 160 years. 🙂

[Adrian R2Participant @adrianr2]

True, but it has been maintained, the most recent just completed at a cost of £7.5m which will be paid for out of tolls. See also Menai bridge emergency closures/repairs. All things exposed to wind and water need upkeep.

The Albion dry dock was empty when I last walked past so hopefully someone has a plan.

[old martParticipant @oldmart]

Replacing catenary cables is a drawback of suspension bridges, it should be much easier with cable stayed versions where one cable can be removed and replaced at a time without the bridge falling down.

[JAParticipant @ja]

The old M4 bridge over the River Wye at Chepstow is a cable stay bridge. This was strengthened, completely rebuilt, in the late 1980s without closing the motorway (prior to the Second Severn Crossing).

JA

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