What are these parts on the ECML Bridge over the Idle at Retford?

[jukebox]

Can anyone tell me, or have an educated guess what these bars are, circled in red, under the arches on the ECML bridge of the River Idle at Retford?

 

 

They look to be possibly made of rail.

 

 

They are not new - they appear in the BR era photos I have, before the deck and handrail was modified.

 

 

 

Cheers

 

Scott

Edited May 15, 2017 by jukebox

[uax6]

No Idea, but could they be supports put it to support the centring that the arches were built on?

 

Andy G

[The Johnster]

I've got no idea either, but they might be flood level indicators, especially as in one photo one of them looks as if it was once painted white.  Centring supports would, I'd have thought (though I profess no great erudition in the matter) have had one in the middle as well.  

[Jonboy]

Could they be a deterrent to boats getting to close?

[tamperman36]

could they be scaffold supports for inspecting the underside of the arch.

[rockershovel]

could they be scaffold supports for inspecting the underside of the arch.

Inspection would probably be by boat. They look out of character to be part of the original structure. There are obvious repairs over time - particularly, areas of mismatched brickwork - I'd guess that they are later temporary works intended to support working platforms for that work, and left in situ for future re-use and/ or to save the cost of removel

[jukebox]

Thanks for the suggestions, everyone

 

A couple more observations; they are under all the arches on both sides - even the landlocked ones that are next to the abutments, so I don't think they would be boat bumpers, Jonboy.

 

When I look at the photos magnified, it appears they are four rails projecting out from the wall of the pier, and a cross member at the end of the rails, parallel to the pier - so they are quite substantial. They could even be continuous in the centres piers - passing through to come out each side.

 

It's not impossible they are supports for the arch formwork, but I'd have thought they would be at the top of the piers if that were the case.

 

Cheers

 

Scott

[eastwestdivide]

Are the "cross-members parallel to the pier" hard up against each pier? I've seen a number of bridges with rail-built features that look to a layman like reinforcement holding the pier together.

[jukebox]

Are the "cross-members parallel to the pier" hard up against each pier? I've seen a number of bridges with rail-built features that look to a layman like reinforcement holding the pier together.

 

 

Hmmm - now I look closely, I wonder if the cross member is an optical illusion, and there are just the rails, projecting out from the walls. Here's a blow up:

 

 

(Click on this for greater enlargement)

[unravelled]

According to one of my books, they are termed needles, and as has been said are potential supports for centering. Possibly installed because of a fear of problems with subsidence, they would allow rapid installation of temporary support for the arches. They need to be well below the springing of the arches to allow the centering to be jacked into position and released.

 

Hth

 

Dave

[jukebox]

Excellent - thanks for that, Dave

[Trog]

According to one of my books, they are termed needles, and as has been said are potential supports for centering. Possibly installed because of a fear of problems with subsidence, they would allow rapid installation of temporary support for the arches. They need to be well below the springing of the arches to allow the centering to be jacked into position and released.

 

Hth

 

Dave

 

Would a few bits of rail be man enough to take the weight of a failing arch? Especially as if the arch is failing due to subsidence the first thing to sink would be the pier the rails are through.

 

Surely it is more likely that they were installed to support a scaffold platform to allow brickwork repairs or repointing, reducing the need to use boats or a support structure in the river which would be vulnerable in the event of heavy rain causing the river to spate. Once the rails were in it would only be sensible to leave them in place ready for next time.

[chris p bacon]

Would a few bits of rail be man enough to take the weight of a failing arch? Especially as if the arch is failing due to subsidence the first thing to sink would be the pier the rails are through.

 

Surely it is more likely that they were installed to support a scaffold platform to allow brickwork repairs or repointing, reducing the need to use boats or a support structure in the river which would be vulnerable in the event of heavy rain causing the river to spate. Once the rails were in it would only be sensible to leave them in place ready for next time.

You would be surprised at how small a section would be required for this, it isn't to take the whole weight but to stabilise any movement such as the arch "flattening" .

 

I would doubt if it was installed for what would be a once in a century job such as repointing.

[rockershovel]

Modern practice for repointing would just be a tubular scaffold.

 

There are obvious sections of mismatched brickwork - my guess is that they were installed to support a fairly substantial working platform for brickwork, possibly a compressor or small drilling rig for grouting, and left in place for possible future use

Edited May 15, 2017 by rockershovel

[chris p bacon]

Modern practice for repointing would just be a tubular scaffold.

 

There are obvious sections of mismatched brickwork - my guess is that they were installed to support a fairly substantial working platform for brickwork, possibly a compressor or small drilling rig for grouting, and left in place for possible future use

That's quite feasible, although I would question why it's on the bank where it wouldn't be needed (unless to provide balance weight.

[awoodford]

I don’t know what they were for, but I’ve seen them elsewhere, in particular on a small girder bridge over a stream where I lived as a kid. At the time it amused us to use them for swinging under the bridge from one side of the line to the other, rather than scrambling across the track (southern electric third rail and all that). I suppose it’s possible the bridge was converted from arch to girder at some later date if the bars were indeed concerned with supporting an arch.

Alan.

[rockershovel]

That's quite feasible, although I would question why it's on the bank where it wouldn't be needed (unless to provide balance weight.

The work platform might have been a standard structure which was moved from arch to arch as work progressed. A platform like that would been made off-site and brought to the location. It would need to be big enough and strong enough to support the intended works, and also at the required level - the needles would provide that

[Trog]

That's quite feasible, although I would question why it's on the bank where it wouldn't be needed (unless to provide balance weight.

 

If you were going to install a piece of rail like that the hard bit would be drilling the hole to put it through, for the land based piers it would be easiest to do that from the dry side. When you fed the rails through it would be no extra effort to use pieces of rail that stuck out both sides, and perhaps easier as a balanced piece of rail would be more likely to lie flat in the hole while you concreted it in. The land side rails might be a bit overkill but why not have them if they come free with the riverside ones you really need. It would also allow the use of a standard deck, and would keep that deck clear of a reasonable level of flood water should the river rise.

[rockershovel]

If you were going to install a piece of rail like that the hard bit would be drilling the hole to put it through, for the land based piers it would be easiest to do that from the dry side. When you fed the rails through it would be no extra effort to use pieces of rail that stuck out both sides, and perhaps easier as a balanced piece of rail would be more likely to lie flat in the hole while you concreted it in. The land side rails might be a bit overkill but why not have them if they come free with the riverside ones you really need. It would also allow the use of a standard deck, and would keep that deck clear of a reasonable level of flood water should the river rise.

"Why not have them"? Because they cost money. Every part of that structure is designed to be the most cost-effective solution to a perceived problem or requirement. If any part of that structure needs attention, it all needs attention, or will in due course. If the centre, river section is exhibiting differential settlement relative to the onshore section (which is a common problem) then the arch nearest the bank is a stress concentration zone.

 

Any work platform would need to be strong enough, and level at the required elevation, above the water and providing access to the work area. Those needles look like they provide that support.

[jukebox]

That's quite feasible, although I would question why it's on the bank where it wouldn't be needed (unless to provide balance weight.

 

 

Correct me if I'm wrong, Dave, I think the point you are trying to make, is that if the needles are to support scaffolding of some kind, why are they also inserted into the arch piers on the sides of the abutments? (the arch on the far right of my first photo is partially ashore, and lands against the right hand abutment - even more so the one on the left, seen in the 4th photo, which is totally land locked)

 

Considering the substantial scaffold required to create a deck to repoint from, you would think it would not be that much more of an effort to build a struts down into the water on such a temporary deck -  especially as you could schedule that works for when the flow was low, as the need for repointing wouldn't develop overnight -  and that effort would only be required once, maybe twice per century - which makes driving multiple steel beams all the way through the piers seem like a big overkill for something used so sporadically.

 

However if those needles had to handle a large distributed load - i.e. stopping the arch from collapsing, or jacking the arch - I could understand the effort, and the need for needles inserted into the bank side arches.

 

It's an interesting discussion - just a shame we don't have a definitive answer.

[awoodford]

It looks to me as though 'unravelled' is on the right track. Having had a search around the internet, I think they are needle-beams, traditionally used to support walls while underpinning the foundations. So they could have been pushed through the piers at a later stage while strengthening the bridge at some time.
Alan.

[Trog]

"Why not have them"? Because they cost money. Every part of that structure is designed to be the most cost-effective solution to a perceived problem or requirement.

 

Just how much do you think a couple of extra feet on the end of a piece of scrap rail you are installing anyway would cost a railway company?

 

As for them being used to support failing arches look at the photos the arches are perfectly round, the top of the parapet is as straight as a ruler and there are only a few patches of different bricks to be seen with the others all being the same. Does not look like a bridge that has ever been in any great distress to me.

 

Also if the bridge had failed the arches would have needed to be replaced quickly so as not to delay traffic, and the way to do that would be to put a steel beam deck across the remaining sound piers, not rebuild new brick arches.

[chris p bacon]

Just how much do you think a couple of extra feet on the end of a piece of scrap rail you are installing anyway would cost a railway company?

 

As for them being used to support failing arches look at the photos the arches are perfectly round, the top of the parapet is as straight as a ruler and there are only a few patches of different bricks to be seen with the others all being the same. Does not look like a bridge that has ever been in any great distress to me.

 

Also if the bridge had failed the arches would have needed to be replaced quickly so as not to delay traffic, and the way to do that would be to put a steel beam deck across the remaining sound piers, not rebuild new brick arches.

I'm not saying that this is the case with the bridge in question but you'd be surprised just how little work is done to rectify any problems with a bridge such as this.  

 

I have at present some pre-grouping railway documents I'm helping to archive and there are a few instances where every ha'penny is accounted for and not a penny more spent than need be. So it's quite possible that there was a perceived fear of subsidence hence the needles, but the complete replacement of the bridge with a new deck may be a cost too great to bear.

[eastglosmog]

Only just checked out where this bridge is.  It is on the eastern edge of the worked area of the Yorkshire Coalfield.  The needles are therefore very likely to be supports for centering to support the arches if the bridge were to be subject to mining subsidence (there used to be plenty of examples of this in South Wales).  Probably inserted either by the National Coal Board or British Railways back in the 1960s but never actually needed as, so far as I know (having just checked it on the Coal Authorities website), no mining actually took place within influence distance of this bridge.

[unravelled]

For those interesdted in bridge repair, my reference is

 

Railway Bridge Maintenance

 

Turton, Frank

 

Published by Hutchinson Educational Ltd, London (1972)

 

ISBN 10: 0091089204 ISBN 13: 9780091089207

 

I bought it, and a companion volume on (then) current railway bridge construction many years ago.

 

This is a sneaky photo of the image of mining subsidence support using similar needles. Unfortunately the photo distortion hides some og the subsidence movement.

 

 

Going back to the original photo, an alternative possibility is to do with flood risk rather than mining subsidence. Being able to support the arches at short notice after a flood has compromised foundations might be useful. It looks as if the side arches were provided to prevent restriction to flow under flood conditions.

 

Thanks

 

Dave