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Concrete shelf on the Shropshire Union


Heartland

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The building, it is said, by the DIWE or BW in the 1950's of a concrete bank wall with a shelf has recently been raised as question during a talk on the Shropshire Union Canal. Yet the reason for this type of construction remains unclear. 

 

Concrete side walling was adopted by the LMS on some of their canals and can be seen seen in the Stoke on Trent area of the Trent & Mersey Canal. The Grand Union also adopted concrete walls during their widening of parts of their waterway in the West Midlands. But with the SU work the ledge is said to stand out for some 4 inches below the water line and this had affected those who moor alongside the towpath. Have any boater noticed this issue on the SU ?

 

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If it were only 4" we would all cheer, its often over a foot and the depth is variable so you never know when mooring until you hit it or find the boat climbing on to it.

 

We use alloy car wheels with tyres, less heavy to maul around.

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1 hour ago, Heartland said:

the reason for this type of construction remains unclear. 

 

It looks like it was done on the cheap - a couple of vertical feet of shuttering against the existing bank and then the concrete poured to the top without worrying if some spilled out at the bottom.

 

I don't think it was deliberately designed to have the shelf, it's just a side effect of the construction method.

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On 14/03/2021 at 13:15, TheBiscuits said:

 

 

 

On 14/03/2021 at 13:15, TheBiscuits said:

 

It looks like it was done on the cheap - a couple of vertical feet of shuttering against the existing bank and then the concrete poured to the top without worrying if some spilled out at the bottom.

 

I don't think it was deliberately designed to have the shelf, it's just a side effect of the construction method.

Lets face it, the working boats didnt want to moor up in a nice sunny spot they just kept going to their tie up places. 

PS. I cant get rid of the double quote 

Edited by Athy
To remove double quote.
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I ended up using Mini Tyres with inflated innertubes in them, floated between the boat and coping stones to guarantee not banging the hull sides on the concrerte step all night. There are sections of the concrete sides on the K&A between Dundas and Avoncliffe, which also have a submerged shelf, which is why I originally aquired the tyres.

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I wonder if this was an experiment to find a quick way of making up the banks, without thinking of the implications of what was done. Are there any images of the canal bed to show what happened. Such images would probably confirm the issue of insufficient shuttering,

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56 minutes ago, Heartland said:

I wonder if this was an experiment to find a quick way of making up the banks, without thinking of the implications of what was done. Are there any images of the canal bed to show what happened. Such images would probably confirm the issue of insufficient shuttering,

 

http://www.canalscape.net/Book 14 - 2018/Canalscape Book 14.htm

 

includes this photo of the Middlewich breach, helpfully taken from the offside

 

https://www.canalscape.net/Book 14 - 2018/Canalmanac 2018/LR Middlewich Breach.jpg

 

Zooming in a bit gives this section of the concrete wall where the breach scoured a lot of the silt from it.

 

shelf.jpg.b3f0349a252c4223b66027e029d099f8.jpg

 

As you can see, the "shelf" is very irregular compared to the straight wall.

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18 hours ago, TheBiscuits said:

 

It looks like it was done on the cheap - a couple of vertical feet of shuttering against the existing bank and then the concrete poured to the top without worrying if some spilled out at the bottom.

 

I don't think it was deliberately designed to have the shelf, it's just a side effect of the construction method.

I seem to remember in the very early 60's shuttering ready to have concrete poured. that would back this theory up.  As when the project started in 1950's? there was still a fair amount of narrow boat traffic between the North west and the Black Country and the need to protect the bank erosion. This changed to concrete piling early 60's and moved onto steel piling 

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Although as a rider this suggestion is at odds with a Sphere article dated 09th February 1957 where the British Transport Waterways had introduced concrete piling. To combat erosion of the bank sides, BTW had developed reinforced piles for use on South Eastern Waterways and North Eastern Waterways. They used piles held together with old railway lines. A plant was developed at Marsworth on the Grand Junction and other plants were to be developed at Market Drayton (SU), Northwich (Weaver) and Burnley (Leeds & Liverpool). Another plant already existed at Crowle (S &SYN).

 

Such work seems to have been done on a professional basis and is evidently different from the shuttering method where the shelf is an unfortunate byproduct of this process.

 

 

  

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I'm not trying to defend the shelf, but I believe that much of the Shroppie was in any case built as a V section, with a flat bottom, so sides were not vertical, and mooring would always have been difficult.  This ties in with the fact that this canal (Birmingham & Liverpool Junction, from Cut End at Autherley to Nantwich) was built for fly-boating, where boats would only stop at wharves - which of course still have vertical sides.  There was then no need to stop anywhere else. 

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  • 2 weeks later...

I had a look at a forum post for the Middlewich Breach in 2018. Much of the side wall seems to be precast concrete strips held together by a piece of rail as mentioned in the Sphere article. This seems to indicate that the work was done by BTW in the 1950's.

 

The concept of using shuttering and pouring concrete into the space, still needs a case example. 

 

As to Hastings suggestion regarding the Telford design, would this give a perception of  a shelf ?  

 

  

MiddlewichB1.jpeg

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31 minutes ago, Heartland said:

I had a look at a forum post for the Middlewich Breach in 2018. Much of the side wall seems to be precast concrete strips held together by a piece of rail as mentioned in the Sphere article. This seems to indicate that the work was done by BTW in the 1950's.

 

The concept of using shuttering and pouring concrete into the space, still needs a case example. 

 

 

The precast concrete pilings are good bits where there isn't a shelf, and that's how the offside near the breach is supported.  That photo is taken from the towpath at the breach site, but the washwall on the nearside is shown in the earlier zoomed picture I posted.

 

The concrete edges that have the shelf were cast in situ - they are nothing like the concrete pilings - and have the shelf.  Sadly I can't find any very good photos of the shelf online - probably because it's not usually a topic of much interest - nobody takes good clear pictures of it when a drained bit of canal makes it visible.

 

 

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Edited by TheBiscuits
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Thanks that helps to understand that there was a process of transition leading concrete piles depots being established by BTW.

 

I found an image in the Waterways Archive which is dated 1951 and shows, rather poorly, concrete walling being done near Norbury. So the implication might be that the DIWE were responsible for the "shelf" !

 

 

Norbury.jpg

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https://collections.canalrivertrust.org.uk/bw192.3.1.34.9.3

 

BW192/3/1/34/9/3

Bank reinforcement on the Shropshire Union Canal

Description

Black and white photograph showing workmen reinforcing the bank, a mechanical shovel shovelling concrete off narrowboats and an overhead hopper for concrete positioning.

 

v0_web.jpg

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https://collections.canalrivertrust.org.uk/bw192.3.1.29.14.7

 

BW192/3/1/29/14/7

Towpath wall shuttering at Four Crosses on the Staffordshire and Worcestershire Canal

Description

Black and white photograph showing support frames on the side of the wall, and workmen and equipment on top of it. There are several industrial chimneys visible in the background.

 

v0_web.jpg

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41 minutes ago, TheBiscuits said:

https://collections.canalrivertrust.org.uk/bw192.3.1.34.9.3

 

BW192/3/1/34/9/3

Bank reinforcement on the Shropshire Union Canal

Description

Black and white photograph showing workmen reinforcing the bank, a mechanical shovel shovelling concrete off narrowboats and an overhead hopper for concrete positioning.

 

v0_web.jpg

I remember seeing similar work being done on the GU at Knowle between the top lock and the Kenilworth Road bridge c. 1973. A trench dug into the sloping bank, shuttering and concrete placed, and then the dredger came along and transferred the soil from in front of the new wall to behind it. And in one area enough was dredged out that a section of the new wall failed and slid into the canal. They just dug a hole in the towpath again, dragged the bits of failed wall into the hole, built a new section of wall in the same way, then dredged and backfilled again. 

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On 19/03/2021 at 10:09, Hastings said:

This ties in with the fact that this canal (Birmingham & Liverpool Junction, from Cut End at Autherley to Nantwich) was built for fly-boating, where boats would only stop at wharves - which of course still have vertical sides.  There was then no need to stop anywhere else. 

I have seen an early BW guide, addressed to their hire-boaters, which states that you must not moor anywhere other than at recognised wharves, boatyards, or visitor moorings. 

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Then there are the lengths on the Shroppie where 3 X 2 concrete paving flags are laid at an angle up to the bank and mooring is impossible. 

Seems to be an expensive way of bank protection.

 

I don't think that the step was intentionally shuttered and cast but that is is the bottom of the trench dug in the bank with shuttering above to cast the towpath retaining wall. The spoil still in the canal would then be placed behind the wall to form the towpath and the rough step left sticking into the canal.

From my forays on the step trying to moor, it is very irregular at the edge and at varying heights relative to the water surface, as though it was cast in a rough trench rather than shuttering.

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