Narrow lock chamber construction

[billh]

5 minutes ago, jonesthenuke said:

Just a thought, but are there any derelict locks that would give an idea of construction and design? I am thinking of the scenario where part of the walls have collapsed, thus allowing an insight into brickwork thickness etc.

Aye, there's one at Marple right now, Lock 7, probably others on the flight in the near future😟

[Stroudwater1]

Would the waterways recovery group be a good port of call? Whilst many locks restored are sort of there very much often needs rebuilding and the original methods of construction are in evidence. 
 

As mentioned this would include the course that the sluices take.  It seems important to get that right. Top paddle sluices that when opened at any speed pull boats in a hurry towards the top gates and cill isn’t a good idea. That seems likely to cause more structural damage over time than ones that fill swiftly while maintaining the boat position in the lock quite nicely. BCN, Coventry or S&W are examples of good fillers, Oxford and Cheshire locks less satisfactory. 
 

It’s noticeable too that the Coventry canal locks, Atherstone and Tamworth locks seem to fill at a slower rate than BCN locks. 

[David Mack]

20 minutes ago, Stroudwater1 said:

Top paddle sluices that when opened at any speed pull boats in a hurry towards the top gates and cill isn’t a good idea.

The Perry Barr flight were built with paddle culverts with multiple entry points along the chamber length, including at the bottom gate recesses. That induces less turbulence than having the water all enter at the top end, and also meant that the bottom gates closed automatically on lifting the top paddles. But having balance beams moving with nobody pushing them was deemed a risk to unsuspecting passers by, and the lower culvert entries have been blocked off.

[Chris Bailey]

Good thoughts all - thanks very much - most useful

[Pluto]

The problem is that lock design varied over the life of a canal, with complete reconstruction not being that unusual on successful heavily used canals. Photographic evidence shows Rochdale Canal locks being fully rebuilt from the ground up in three to four days. Upper gate paddles tended to be added when railway competition forced speed through locks to be increased, and other improvements, such as culverts along the length of the chamber, were added. Bottom gate paddles were increased in size to such an extent on the L&LC that counterbalances were required. Every canal had its own solution to the design of locks, and that variation is one of the delights of visiting different canals for me. Unfortunately, in restoration finances often result in standardisation and poor quality concrete design. However, that does not stop research into what was there originally, and how that changed over time, and that information can be used to enhance the visitor 'experience'.

[jonesthenuke]

1 hour ago, David Mack said:

The Perry Barr flight were built with paddle culverts with multiple entry points along the chamber length, including at the bottom gate recesses. That induces less turbulence than having the water all enter at the top end, and also meant that the bottom gates closed automatically on lifting the top paddles. But having balance beams moving with nobody pushing them was deemed a risk to unsuspecting passers by, and the lower culvert entries have been blocked off.

At least some of the Perry Barr flight work as originally intended with automatic closure of the lower gates when filling the lock. I tried this last time we went through (about 3 years ago) and the ones I tried all worked.

 

PS I think there is an Andy Tidy Canal-hunter video showing them working.

Edited March 4 by jonesthenuke
PS added

[cuthound]

4 hours ago, Stroudwater1 said:

It’s noticeable too that the Coventry canal locks, Atherstone and Tamworth locks seem to fill at a slower rate than BCN locks. 

 

That is because they originally relied on gate paddles in the top gate as well as relatively small ground paddles to fill. These were removed when pleasure boating became popular because at that time they were unshuttered, and could send a jet of water more than halfway along the lock, potentially sinking a boat, if they were opened before the lock had filled enough to cover the gate paddle.

 

There used to be lots of locks with unshuttered top gate paddles around, but these were all "sanitised" out by the early 1990's.

[Pluto]

As I mentioned before, upper gate paddles seem to have been non-existent on 18th century locks, and only appeared from the mid 19th century following the start of railway competition. If you look at old photos of the more minor canals, most do not have top gate paddles as they were not worth fitting where traffic was limited. The attached are drawings of the upper and lower sills on the Coventry, with the upper paddle filling the chamber from under the sill. The drawing is from the collection in the Austrian National Archives in Vienna, and are virtually the only detailed engineering drawings of English canal structures I have found from the 18th century. They were drawn in 1795 when a group of Austrian engineers visited England to look, in particular, at the construction of English canals.

[magpie patrick]

Further to @Plutos comments, and ref: the Coventry Canal and others, there simply wasn't a standard way of doing things, or even a standard performance spec. For example, locks on the Neath Canal only had one ground paddle at the top, and never had top gate paddles, speed was presumably not of the essence - other canals may have regarded speed of operation more highly from the outset. 

 

Pluto has done far more research than any of us (probably more than the rest of us put together!) but my suspicion would be that (1) most earlier locks the design was based on what they already knew from nearby navigations (2) once ground paddles were understood gate paddles were not used at the top (with one possible caveat - see below) and (3) two ground paddles at the top was as much about redundancy as it was about speed, and even then may have largely been "other locks have two paddles" - as a general rule if something worked then one didn't fiddle with it. 

 

Caveat - some locks on the main system only ever had one top ground paddle, notably the T&M east of Stone, and Marple Locks - Pluto and I have walked up Marple Locks looking for evidence or otherwise for top gate paddles when new, but there is none. On the T&M locks it would seem odd to have some locks with two top paddles and some with only one, so my suspicion is that those locks with only one top ground did have top gate paddles, but is is only a supposition. At some point the T&M standardised on two top ground paddles as the newer locks at Meaford have this whilst the top lock has only one.

[ditchcrawler]

The River Gipping Trust have restored some locks and of course WRG have worked on several.

2 hours ago, cuthound said:

 

That is because they originally relied on gate paddles in the top gate as well as relatively small ground paddles to fill. These were removed when pleasure boating became popular because at that time they were unshuttered, and could send a jet of water more than halfway along the lock, potentially sinking a boat, if they were opened before the lock had filled enough to cover the gate paddle.

 

There used to be lots of locks with unshuttered top gate paddles around, but these were all "sanitised" out by the early 1990's.

Lots of the GU ones, and the shutters clog with crap and possibly larger fish

[Tim Lewis]

7 hours ago, Stroudwater1 said:

Would the waterways recovery group be a good port of call? Whilst many locks restored are sort of there very much often needs rebuilding and the original methods of construction are in evidence. 
 

As mentioned this would include the course that the sluices take.  It seems important to get that right. Top paddle sluices that when opened at any speed pull boats in a hurry towards the top gates and cill isn’t a good idea. That seems likely to cause more structural damage over time than ones that fill swiftly while maintaining the boat position in the lock quite nicely. BCN, Coventry or S&W are examples of good fillers, Oxford and Cheshire locks less satisfactory. 
 

It’s noticeable too that the Coventry canal locks, Atherstone and Tamworth locks seem to fill at a slower rate than BCN locks. 

The Stroudwater restoration has just had planning permission granted for the ‘missing mile’ which includes two brand new locks so I assume that plans are available from there?

[Martin Nicholas]

Probably the cheapest construction of a narrow lock would be Somerton Deep on the Oxford, with its single leaf gates top and bottom.

 

The chief engineer/architect for the Avon Trust designed wide locks from scratch using modern materials and methods. The gates are steel tubes and plate and they certainly look indestructible. Drawings should be available from the Trust.

[Pluto]

This is Linnet Lock on the Rochdale during rebuilding in 1880. There are several photos, with one having the timing on the back - four and a half days for a complete reconstruction. This happened fairly regularly, so what we are looking at today on a well used commercial canal is unlikely to be what was built. It becomes fairly easy to see where major repairs have taken place once you know what to look for. Regarding technical drawings, the various projections were only just being decided upon in the early 19th century, so anything before that tends to be more of a sketch than a detailed technical drawing. What was relied upon during canal construction were written specifications, with the site engineer holding sketches which he would use to explain to contractors what was required. I did a survey of the bridges between Church and Whitebirk on the L&LC. All were built to the same specification and all had detail differences. Stone size varied depending upon distance from the quarries, with smaller stones  being used on bridges nearer the quarry. It is obvious when you think of the problems in ensuring a safe load when moving the stone. It was also possible to identify the contractor from the way the stones were dressed, with the two or three contractors working to different standards, but to the same specification. 

There is still a lot to find out. For instance, chamber walls seem to have been built with wooden framing by some engineers. I have seen the remains on the Chesterfield, and I have drawings showing that gate anchors involved wooden framing on the GJC locks. I suspect most examples were removed as soon as the wood started to decay. It is an example of change over time, something that many seem to have difficulty in appreciating.

[magpie patrick]

I concur with @Pluto - there is a great tendency to simplify history, and related to that a tendency to think of what we have now or of the recent past as being "original" 

 

more generally, and as an example of the difficulty in interpretation, below are four photographs of the head of locks 9,10,11 and 12 at Marple, taken earlier this afternoon. Lock 9 has a recess on the offside that looks big enough for a single leaf top gate, lock 10 has one half the size, lock 11 has only the curved rebate to allow the top gate to close, whilst lock 12 has a recess big enough for a gate for most of its height but only half the size at coping level. 

 

Did one or more of these locks ever have the gate hinged on the non-towpath side? Are any of these original features? If so (to both questions) which one? 

[ditchcrawler]

When the Ipswich IWA restored one of the locks they found bricked up culverts god knows how many years ago

[David Mack]

3 hours ago, Pluto said:

For instance, chamber walls seem to have been built with wooden framing by some engineers. I have seen the remains on the Chesterfield, and I have drawings showing that gate anchors involved wooden framing on the GJC locks.

We found the remains of timber framing and anchor timbers running back from the lock wall when rebuilding chambers on the Droitwich Barge Canal.

[ditchcrawler]

26 minutes ago, David Mack said:

We found the remains of timber framing and anchor timbers running back from the lock wall when rebuilding chambers on the Droitwich Barge Canal.

[Richard T]

Leicestershire County Records office have a collection of drawings by William Jessop for the construction of the Leicester Navigation. These include details of locks and bridges. I have a copy of the bridge details but not the locks. The locks are broad but the principles will be the same. The catalogue details are below.

 

 

[Chris Bailey]

Thank you - invaluable 

[alan_fincher]

On 04/03/2024 at 09:30, jonesthenuke said:

Just a thought, but are there any derelict locks that would give an idea of construction and design? I am thinking of the scenario where part of the walls have collapsed, thus allowing an insight into brickwork thickness etc.

 

I recall that when there was a massive failure  of one of the sidewalls on a lock towards the end of the Aylesbury arm that CRT had access to plans that they assumed would show how it was built.

 

I may have this slightly wrong, but my memory is that they actually found that the brickwork was about double the thickness of what the plans actually showed.

 

 

 

 

[Pluto]

1 hour ago, Richard T said:

Leicestershire County Records office have a collection of drawings by William Jessop for the construction of the Leicester Navigation. These include details of locks and bridges. I have a copy of the bridge details but not the locks. The locks are broad but the principles will be the same. The catalogue details are below.

 

 

Jessop trained under Smeaton, whose drawings for locks on the Calder & Hebble survive in the Royal Society Archive. No doubt he passed on the benefit of engineering drawings to Jessop, and a few survive by John Rennie, who was encouraged by Jessop. These three early engineers all had some form of academic training, which has supported the idea that academic learning was essential for training engineers. However, if you look at all our early civil engineers, the one thing which seems to unite them is that they have all had some form of training with master craftsmen. Civil engineering in the UK was led by craftsmen engineers, basing their knowledge on what had been passed on to them. Their ideas developed from existing knowledge through trial and error, with little coming from academic processes. Interestingly, on the continent, the engineering profession was very much academically-based, though most did not have the skills necessary to put their ideas into action. In terms of technology transfer, they were hoping to get skilled craftsmen from the UK, which is where we excelled. UK academic engineering training only really began after the railway age began, so they were years behind the continent. For example, calculus was not widely accepted by British mathematicians and academic engineers until thirty or forty years after the continentals. For about sixty years, from 1760-1830, it was British craftsman engineers who led the world in engineering excellence - its a pity our society does not value those skills sufficiently today.

[Mike Todd]

On 03/03/2024 at 15:31, David Mack said:

Arrive at the top when both locks are full and you empty 2 lockfuls of water into the lower pound. Arrive at the bottom and you take 2 lockfuls of water from the upper pound. If they had been 2 conventional single locks, both of those scenarios would only use one lockful.

But if the sideponds are used properly (and I accept that sometimes they aren't and last time I came through one was out of order anyway) that should save 1/3-1/2 a lockful which should make the consumption similar to the shallower locks below (staircase excepted).

And apart from the earthworks, with less lock wall in total, one fewer gate and set of paddles, a little cheaper in construction cost too. And presumably somebody assessed that cost saving as being worth the increased water consumption in the longer term.

I thought that cost was also the original reason for building most of them at the outset.

 

The other upset to the calculations at Droitwich is the problem with the 'tunnel' that has led to one paddle being locked off to reduce flow. 

 

Also note that two locks with a short pound between will vary in their water consumption, depending on the state of the pound and the willingness of boaters to follow the rule about setting the lock ahead to avoid, if possible, water going over the weir.

 

However, I do recall that many, if not all, canals were built on the assumption that water would be fed downhill fairly continuously. Without this, lower stretches risk running dry if traffic is unduly asymmetric.

[Jen-in-Wellies]

On 04/03/2024 at 09:30, jonesthenuke said:

Just a thought, but are there any derelict locks that would give an idea of construction and design? I am thinking of the scenario where part of the walls have collapsed, thus allowing an insight into brickwork thickness etc.

Surely you'd want to copy the design of a lock that hasn't collapsed! Otherwise it is only an insight in how not to do it. 😀

[Ronaldo47]

On 04/03/2024 at 17:41, Pluto said:

 Regarding technical drawings, the various projections were only just being decided upon in the early 19th century, so anything before that tends to be more of a sketch than a detailed technical drawing. 

I understand that the modern engineering drawing conventions that we use today, were first devised by the French, and were considered to be so much better than previous practice that they were originally classified as a State Secret. 

Edited March 5 by Ronaldo47
typos

[jonesthenuke]

1 hour ago, Jen-in-Wellies said:

Surely you'd want to copy the design of a lock that hasn't collapsed! Otherwise it is only an insight in how not to do it. 😀

I think my suggestion is largely valid, though I accept your argument. Abandoned locks may only have collapsed due to decades of dereliction and zero maintenance and thus this does not necessarily negate the value of the original design. Also I suspect there are some part demolished locks (or photos of them in a part deconstructed state) which will also give an indication of the designs used.