Northampton Arm, Grand Union Canal - 17/4/18

[gbclive]

Navigation between Lock 1 and the winding hole below lock 17, Northampton Arm, Grand Union Canal is closed.

The counter balances on the lift bridge 7, Ellis Bridge have broken, the bridge deck is stuck in the down position.

A team will be on site Wednesday 18 April to assess crane needs to lift the bridge deck off.

This notice will be updated by 4pm 18/4/2018 when further information will be available.

[Scholar Gypsy]

How on earth did that happen, to both at the same time? Even if I wanted to do that deliberately, I can't really see how I could.

I see the byewash has got blocked again.

[starman]

Is this a permanently open one? If so then it shouldn't be hard to pull it up and bodge a temporary fix.

[ditchcrawler]

Were these the ones that were put back to look nice?

[TheBiscuits]

2 hours ago, gbclive said:

What is the yellow tape to prevent? People walking over a very closed bridge?

It would be more use strung across the water!

[matty40s]

1 hour ago, Scholar Gypsy said:

How on earth did that happen, to both at the same time? Even if I wanted to do that deliberately, I can't really see how I could.

 

I can only see vandalism there, the wood doesn't look rotted but the gates arent chained open. A group slamming it down and then pulling it back up repeatedly could cause the beams to fracture where the two pivot pins go though.

Edited April 17, 2018 by matty40s

[john6767]

25 minutes ago, TheBiscuits said:

What is the yellow tape to prevent? People walking over a very closed bridge?

It would be more use strung across the water!

The broken beams are just resting on the uprights, so potentially dangerous.  Once they are removed that will make it safe.

 

14 minutes ago, matty40s said:

I can only see vandalism there, the wood doesn't look rotted but the gates arent chained open. A group slamming it down and then pulling it back up repeatedly could cause the beams to fracture where the two pivot pins go though.

If it was not actually fastened open and was just using the counter weights to keep it open, this would seem to be the most likely cause.  The solution will probably be to remove the bridge I think, why waste the money on repairing it.

[gbclive]

2 hours ago, Scholar Gypsy said:

How on earth did that happen, to both at the same time? Even if I wanted to do that deliberately, I can't really see how I could.

Both beams have failed at the hinge / pivot point, so the point of max bending moment IIRC.

See the close up of the break - my best guess is rot compundered by the basic design, as the cross section is reduced at this point by the insertion of the hinge bolts. Of course there are probably hundreds of similar ones that have lasted donkeys years. Once one beam failed, all the weight would have transferred to the other.

We are actually stuck descending in the the flight with short pounds and some of the gates leak badly, so this is our mooring to hunker down for a few days 

Enough beer and curry for a week - then we will need a plan B.

[TheBiscuits]

6 minutes ago, gbclive said:

this is our mooring to hunker down for a few days 

 

That's a candidate for MLAT

[gbclive]

22 minutes ago, TheBiscuits said:

That's a candidate for MLAT

Mutual legal assistance treaty?

Or MLAT - Multilateration is a proven technology that has been in use for many decades. It was developed for military purposes to accurately locate aircraft — many of which did not wish to be “seen” — by using a method known as Time Difference of Arrival (TDOA).

OK - I give up - it’s probably rude?

[TheBiscuits]

14 minutes ago, gbclive said:

Mutual legal assistance treaty?

Or MLAT - Multilateration is a proven technology that has been in use for many decades. It was developed for military purposes to accurately locate aircraft — many of which did not wish to be “seen” — by using a method known as Time Difference of Arrival (TDOA).

OK - I give up - it’s probably rude?

Moored Like A (BLEEP). Twerp doesn't quite match, but you get the idea

It's a Facebook group where people share photos of inconsiderate mooring of boats, and without the back story that photo would be a gem.

[ditchcrawler]

1 hour ago, john6767 said:

The broken beams are just resting on the uprights, so potentially dangerous.  Once they are removed that will make it safe.

 

If it was not actually fastened open and was just using the counter weights to keep it open, this would seem to be the most likely cause.  The solution will probably be to remove the bridge I think, why waste the money on repairing it.

I think it was a waste of money putting it in about 5 or 6 years ago

[gbclive]

Thanks for that  

The sad thing is that I had my Jeramy Clarkson smugger than a very smug thing look as I surveyed our handywork 

We are not in a hurry, Pink Floyd playing at an appropriate volume and we have an unusual vista with both banks some distance away.

So for us all is well with the world..............for now.

Unfortunately some of the other “detainees” are not so lucky and are a tad frustrated at the lack progress.

[gbclive]

2 hours ago, matty40s said:

I can only see vandalism there, the wood doesn't look rotted

On reflection you might be right Matty.

A few more pics.

[gbclive]

Update Wed 18 April 1100 from the team of 3 CRT assessors.

Apparently their main problem is obtaining permission to move the nessessary equipment onto the site as the land belongs to an industrial estate.

They thought Thursday or possibly Friday for a resolution.

With regard to the cause, they believe that water had caused some rot around the bolts at the hinge. Apparently they have had similar problems with gate balance beams and did not think vandalism was a factor.

Incidentally, Richard Parry is due here on Saturday for an IWA event, so perhaps this might help 

[gbclive]

From CRT:

The crane will be onsite tomorrow (Thursday) to remove the bridge.

Expected to re open the navigation by 12 noon.

The notice will be updated when the removal is complete.

[mark99]

I looked at images yesterday and thought same as GB Clive. One failure triggers the next. Propagation.

 

Edited April 18, 2018 by mark99

[john6767]

31 minutes ago, mark99 said:

I looked at images yesterday and thought same as GB Clive. One failure triggers the next. Propagation.

 

Was it chained open then?  If it was not, like the permenatly open ones on the South Oxford, then one beam failing would mean that the bridge would just close, there would be no additional load on the other beam.

[gbclive]

2 hours ago, john6767 said:

Was it chained open then?

I’ll ask the CRT guys if I see them tomorrow.

[gbclive]

2 hours ago, john6767 said:

 If it was not, like the permenatly open ones on the South Oxford, then one beam failing would mean that the bridge would just close, there would be no additional load on the other beam.

I’ve had a couple of beers, so brain even fuzzier than usual - however, at the instant that one beam broke and before the other beam overcame inertia and stared to move as the bridge fell back to the closed position, would not twice as much weight be supported by the unbroken beam?

[gbclive]

It’s now open  - will post a pic later.

[john6767]

3 hours ago, gbclive said:

It’s now open  - will post a pic later.

Great to hear, enjoy the river.

[gbclive]

Final thoughts:

The bridge was not secured in the up position so was operational but seemed mainly decorative in its purpose.

Once the tracked crane had access to the site, the deck and beams were quickly removed.

We saw a couple of youfs operating a similar nearby bridge the next evening - no obvious reason other than they were bored. When they spotted us they disappeared sharpish.

To me it looked like one of the beams was severely rotten around the hinge bolts - see pic. The other much less so.

Incidentally, we spoke to one of the engineers - he is based in Liverpool and was also called out to a job on the K and A last week, so he certainly gets around.

I guess it was just lucky no one was hurt (or worse).

The Nene has been worth the wait 

[john6767]

In my opinion the Nene gets better further  down, below Wellingborough 

[David Mack]

On 4/18/2018 at 11:30, gbclive said:

With regard to the cause, they believe that water had caused some rot around the bolts at the hinge. Apparently they have had similar problems with gate balance beams and did not think vandalism was a factor.

The bridge beams look to be softwood, so unless they are well injected with preservative they aren't going to last very long. Balance beams are usually oak.