The Haven Bridge

[Hockham Admiral]

Griff said:

So I am leaving it at that. I have thanked him for his timely remarks and he did his best with interviewing his staff, even though imho they were being economical with the truth.  No need to flog a dead horse.  Robin is of course aware of the communications I have been carrying out.  I have invited said operations manage to have a read of this thread and make comment if he wishes too.  If nothing else, I would hope that me getting onto Peel will hopefully sharpen up the staff that operate the bridge into being somewhat more on the ball and not taking us leisure craft for granted, otherwise they will suffer yet another internal investigation.  Eventually some mud will stick.  There isn't and never has been smoke without fire.

I think that really sums it up, doesn't it?

Congratulations to you, Charlie on getting so far and keeping us updated throughout this sorry saga.

[FairTmiddlin]

But! and here is the view of an Engineer

Haven Bridge does not rely upon any locking mechanism or PAWLS

These are not Pawls but guides and anti swing locks to one guide the bridge to lock down straight and secondly stop any swing sideways in any wind

And no they are still the same today

As for their explanation

"If the bridge had been lifted and closed again with the PAWLS in an unlocked position then the bridge would have been unsafe to cross and potentially a catastrophic failure could have resulted in the bridge sections failing and falling into the River."

The Bridge does not rely upon the centre of the bride to bear the weight of the closure It's too flimsy for that

Not a very good photograph

The bridge weight is borne by the large rear plates which in turn is borne by a huge metal plate sunk into the pier. The whole of the bridge rotates on a very heavy Victorian Forged steel gantry which is piled into the river bed. The nice stone abutments are purely for show 

So The Bridge cannot just fall into the river because the middles do not meet (I have seen in the past one section of the bridge raised and the other down )So that is Bull Crap.

How do I know this?

My next door neighbour at number 5 New road Fritton, was a certain Mr Sharman who was the cheif Bridgemaster for Great Yarmouth Port and Haven Authority and I had the grand tour of the bridge when I was about 12

[ExSurveyor]

Ah but they didn't have elf and safety then

The same reason they closed the QE11 bridge today ( but not the tunnels ) when they towed a WW11 bomb down river,  the very same one they had managed to dig up and move onto a barge without it going bang. 

[BroadAmbition]

Well FaitTmiddlin, great post was that un. Most interesting, a gripping read. Hope the Port manager sees it!

I’d quite like a grand tour mysen

Griff

[Meantime]

11 minutes ago, psychicsurveyor said:

Ah but they didn't have elf and safety then

The same reason they closed the QE11 bridge today ( but not the tunnels ) when they towed a WW11 bomb down river,  the very same one they had managed to dig up and move onto a barge without it going bang. 

Now I'm no engineer, but when it was still in the dock they closed the airport and evacuated houses around it in case it exploded and the shock wave through the water and the ground caused buildings to collapse. So what was protecting the tunnels from exactly the same thing?

[MauriceMynah]

I have no doubt that the explanation given by the Peel Ports manager was a cover story, but that changes nothing. Backside covering and face saving has been done. The line has been drawn under the issue and the matter closed. Further communications with that authority will almost certainly remain unanswered, as will any further questions we have.

 

As far as the closing the QEII bridge but not the tunnel, Yep, That's strange. I would have thought the tunnel was far more  vulnerable to an explosion on the surface above it. still, such an explosion might have raised the bridge, causing it to fall in the river with or without PAWLS.

What does "PAWLS" stand for... I take it it is an acronym.

[LondonRascal]

What a place this is eh? Photos, evidence explanations and local knowledge to slice through the 'technical gibberish' that had been sent out by Peel Ports to explain a defect that if had indeed existed would not have caused the bridge to catastrophically fail and fall into the river.

Great stuff and fascinating photos too.

 

[LondonRascal]

Seems a PAWL is, well a hook that engages into the Ratchet.

[Hockham Admiral]

It's used when you're winding a heavy object up in case the winding motor (or you) fails. Then it doesn't smash down.

[Vaughan]

This is how I have always understood a winch pawl. Even the Albion has one, on her halyard winch.

[donnygeoff]

so if a PAWL, is a part of a ratchet system, what are the things in the pictures above, as I can not see how they would stop it falling if the PAWLS failed.

[Hockham Admiral]

Exactly, Vaughan. 

If that smashed down I can imagine it doing some personal damage.

[Vaughan]

So we are saying that Haven Bridge is a twin bascule bridge, like Tower Bridge, which is balanced by counter weight and the lifting is effected by the transfer of weight, usually in hydraulic tanks?

In which case I agree with FairTmiddlin. What have pawls got to do with it?

[grendel]

1 hour ago, psychicsurveyor said:

Ah but they didn't have elf and safety then

The same reason they closed the QE11 bridge today ( but not the tunnels ) when they towed a WW11 bomb down river,  the very same one they had managed to dig up and move onto a barge without it going bang. 

I beg to differ - they did close the tunnels as well- how do I know - I was sitting on the slip road off the A2 with nothing moving on the M25 for 20 minutes. the really good news is the discovery of a second bomb, not half a mile from the bridge in Grays

[MauriceMynah]

Don't suppose there's anything near Canvey Island is there?

[grendel]

Pawls can also be the locking pins that slip into place once you have a bridge (or other piece of equipment raised to stop it slipping back) (or indeed when lowered to stop it being raised accidentally) if these are hydraulic, and a sensor fails to register them as locked in place (or unlocked) I can see that from an elf and safety point of view, you would be unable to proceed, of course this failure can be as simple as a blown bulb in the indicator panel

[Regulo]

Oi, MM! That's a bit too close to me!

Locking pawls on some bridges have to be extended mechanically I believe, and if not fully engaged signal such to the bridge controllers.

Edit: See Grendel's post above. I was still typing!

[ExSurveyor]

17 minutes ago, grendel said:

I beg to differ - they did close the tunnels as well- how do I know - I was sitting on the slip road off the A2 with nothing moving on the M25 for 20 minutes. the really good news is the discovery of a second bomb, not half a mile from the bridge in Grays

Sorry,  only heard the bridge was closed. 

[JohnK]

Right next to the QEII bridge is an aggregates site whose products come from dredging. They regularly dredge up WWII ordinance and have to close the site whilst it’s dealt with. The scary part is they’re often not noticed until they appears on a pile after being dredged and passing along a few conveyors!


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[grendel]

well there is a bomb travelling down the Thames, where do you want it delivered?

Though if we see nyx parked under Haven bridge with you manically hammering a large cylindrical metal object.......

[Vaughan]

Locking pins are also used on railway swing bridges but I have never seen them called pawls. As Robin's diagram shows, a pawl will allow a ratchet to rotate one way, but not the other. That is not the same thing as locking a bridge span into place, when stationary.

If they had referred to a locking mechanism in their letter, it might have been understandable.

[Regulo]

I think the correct term is "nose bolts". That's the term used on Tower Bridge.

[grendel]

Apparently (reading up on Bridge pawls) Tower bridge in london suffered the same issue - modern heavy traffic is too much for the structure, and causes the locking pawls to get out of alignment, this has been fixed on tower bridge, so maybe it requires some major refurbishment.

[grendel]

engineers speak engineerese, they could as easily have been called futtock pins or gudgeon clamps, the explanation was probably passed to the manager in terms he was able to understand.

[Meantime]

45 minutes ago, MauriceMynah said:

Don't suppose there's anything near Canvey Island is there?

Why is Canvey Island closed as well?