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Posted

I can't figure it out. Long brick sheds that house mostly litter and long stout planks. Seem to be at almost every bridge on the Shropshire Union.

 

The planks seem long enough to span the bridge hole. My best guess is that they are either to provide a temporary crossing or a platform for bridge maintenance?

IMG_20201113_113751.jpg

Posted

They are for stop planks. A lot of the Shroppie is on an embankment and if there is a leak, stop planks can be inserted to avoid draining the entire canal.

Posted

I see! Thank you yes this is on an embankment.

 

Would they be inserted horizontally over the hole to plug it? Or would they create a barrier at the bridge hole like a temporary lock gate? How often have they been used?

Posted

And CRT hardly ever use stop planks these days. They sit there for years in their little brick-walled concrete-roofed huts, under corrugated iron roofs or occasionally in open racks, slowly rotting, so that when the canal does need to be stopped off nobody knows if they are safe or not.

It would make far more sense to keep them in proper dry storage in a depot somewhere and transport them to site when needed.

Posted
4 minutes ago, David Mack said:

And CRT hardly ever use stop planks these days. They sit there for years in their little brick-walled concrete-roofed huts, under corrugated iron roofs or occasionally in open racks, slowly rotting, so that when the canal does need to be stopped off nobody knows if they are safe or not.

It would make far more sense to keep them in proper dry storage in a depot somewhere and transport them to site when needed.

Whilst what you say is true, I very much doubt that each and every bridge hole is the same width - it would only need to be 'a couple of inches wider and the planks could fall out, or a couple of inches narrower and the planks wouldn't fit.

 

Central storage would mean having to make them all to the longest length and a qualified saw operator sent out with each batch for a 'custom fitting'

Posted

I believe CRT now use telescopic aluminium stop planks which should fit most slots.

 

Having seen the state of the stop gates on the Nantwich embankment over the last few years I doubt CRT are that bothered about rushing to stop the loss of water.  Especially when you consider the length of the pound there and what it would do to thte town if there was a breach, yet the gates were rotten and immovable for years.

Posted
8 minutes ago, Alan de Enfield said:

Whilst what you say is true, I very much doubt that each and every bridge hole is the same width - it would only need to be 'a couple of inches wider and the planks could fall out, or a couple of inches narrower and the planks wouldn't fit.

 

Central storage would mean having to make them all to the longest length and a qualified saw operator sent out with each batch for a 'custom fitting'

No it wouldn't.  The planks could all be cut to size for each bridge and then stored and marked with the bridge they are intended for.

Posted
1 minute ago, doratheexplorer said:

No it wouldn't.  The planks could all be cut to size for each bridge and then stored and marked with the bridge they are intended for.

Storage space, size and cost ?

 

These are times of minimising costs and inventory, not increasing it.

 

You have obviously neve been involved in industrial manufacture, Kan-Ban, JIT and lean-manufacturing.

Posted
1 minute ago, Alan de Enfield said:

Storage space, size and cost ?

 

These are times of minimising costs and inventory, not increasing it.

 

You have obviously neve been involved in industrial manufacture, Kan-Ban, JIT and lean-manufacturing.

I didn't say it wouldn't take up more space or cost more.  But you said "Central storage would mean having to make them all to the longest length".  Which isn't true.

 

In your example, someone cuts the plank down to the size needed, then the leak is repaired.  So what then happens to the plank?  Is it thrown away?  I would also think that an embankment breach would need a quick response, not slowed down by cutting to size.  So maybe the extra cost would be worth it.

 

I've never worked in industrial manufacture but I have worked in warehouses, storing stock.  Generally stock is stored according to what's needed.  For example, one of the warehouses I've worked in stored artificial christmas trees (no really).  We kept all the sizes in stock, as cutting a 10' tall tree down to 9' would be seen as wasteful and would also mean we would end up with no 10' trees.  Strangely, there were circumstances when trees actually were reduced in size due to a customer request.  Only in extremis though.

Posted

When I got held up by a silted up lock gate, C&RT were able to clear it using the adjacent stop planks to drain a small section. Simple and straightforward.

  • Greenie 1
Posted

Very interesting, I see the grooves int' bridge holes now that I look. 

 

How effective are they actually at stopping the water? Would imagine they're pretty leaky?

 

I imagine it partly comes down to how often they're needed, if not very often then some other kind of adjustable barrier probably makes more sense than storing them at every bridge. But also, how old are they - if they are already there from times gone by, then perhaps it ain't a broke thing to fix?

 

 

Posted (edited)
9 minutes ago, ivan&alice said:

Very interesting, I see the grooves int' bridge holes now that I look. 

 

How effective are they actually at stopping the water? Would imagine they're pretty leaky?

 

I imagine it partly comes down to how often they're needed, if not very often then some other kind of adjustable barrier probably makes more sense than storing them at every bridge. But also, how old are they - if they are already there from times gone by, then perhaps it ain't a broke thing to fix?

 

 

They wouldn't ever be described as 'water tight' I don't believe but they are normally quite effective as they butt up very close and tight and they are relatively smooth machined sides.

 

Unless of course they have indeed been left to rot in the open like these.

 

http://www.towpathtreks.co.uk/photodisplay.asp?ino=0153

Edited by The Happy Nomad
Posted
36 minutes ago, ivan&alice said:

How effective are they actually at stopping the water? Would imagine they're pretty leaky?

They are not watertight when first fitted, but after some ash has been sprinkled along the sides and into any between plank leaks they are nearly watertight.  Watertight enough to deal with a breach  and watertight enough to work in a lock or dock below a set.

For really dry work they can be backed up with a plastic sheet.

 

  Stop planks are usually particular to a set of grooves.  Even if the grooves were built vertical and parallel the earth moves  and they soon end up out of plumb and often skew.  As it is,   most grooves were built with a taper from the top to the bottom.

 

N

Posted
1 hour ago, BEngo said:

They are not watertight when first fitted, but after some ash has been sprinkled along the sides and into any between plank leaks they are nearly watertight.  Watertight enough to deal with a breach  and watertight enough to work in a lock or dock below a set.

For really dry work they can be backed up with a plastic sheet.

 

  Stop planks are usually particular to a set of grooves.  Even if the grooves were built vertical and parallel the earth moves  and they soon end up out of plumb and often skew.  As it is,   most grooves were built with a taper from the top to the bottom.

 

N

I've seen it done and it is really amazing. In this case it was at the top of a lock when the crew wanted to check out a report of problems with a top paddle. To see the ash being applied and very quickly reducing the flow through the gaps to a trickle is something to see. I was told that ash from a nearby steam railway is the best. Seems that not all ash is the same.

Posted
4 minutes ago, Mike Todd said:

Seems that not all ash is the same.

No.  Excel or other ovoids ash is pretty useless because it is all too fine.  You need a few biggish lumps and some pretty coarse fines so that it gets caught in the gaps and progressively  fills them up.

N

Posted

If you want to use them, and they are not padlocked up, be aware that they may be numbered and need to be used in the right order. Or so I was given to understand.

The Shroppie Troll was the ancient forbears of the Shopping Trolley.

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