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magpie patrick

Dundas unmasked

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Tree clearance along the railway at Dundas means that, for the first time in my memory the rail arch under Dundas Aqueduct can be seen from a public place. I knew there was a central pier as the tracks diverge on approach, but one can now see its actually two arches carrying the canal, and the single span which was the only thing one could see previously (because of the oblique angle of view) is actually just window dressing

 

 

20190407_123356.jpg

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Nice spot Patrick.  The aqueduct itself is a thing of beauty, but now there's another great bit of engineering to ogle! :)

 

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9 hours ago, magpie patrick said:

Tree clearance along the railway at Dundas means that, for the first time in my memory the rail arch under Dundas Aqueduct can be seen from a public place. I knew there was a central pier as the tracks diverge on approach, but one can now see its actually two arches carrying the canal, and the single span which was the only thing one could see previously (because of the oblique angle of view) is actually just window dressing

 

 

20190407_123356.jpg

They're not clearing the trees to electrify that bit are they?:unsure:

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33 minutes ago, Wanderer Vagabond said:

They're not clearing the trees to electrify that bit are they?:unsure:

 

No, the electrification stops at Newbury.

 

 

Does anyone know what those bobbles are in the middle of the tracks?

 

 

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6 hours ago, Wanderer Vagabond said:

They're not clearing the trees to electrify that bit are they?:unsure:

No, as MtB said they're not electrifying that bit

 

They have lowered the track to increase the loading gauge, as the cascaded stock resulting from electrification elsewhere wouldn't fit!

5 hours ago, pete23 said:

Yes, I think I do.

 

And...? ?

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It might just be the shadow but the pier looks offset towards the other side of the 'ole (possibly under the canal rather than under the towpath?)

 

Is there a suitable view from the other end? (or does that also rely on the vegetation clearance?)

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7 hours ago, Mike the Boilerman said:

 

No, the electrification stops at Newbury.

 

 

Does anyone know what those bobbles are in the middle of the tracks?

 

 

Deleted 

Edited by rgreg
Talking rubbish

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7 hours ago, Mike the Boilerman said:

 

No, the electrification stops at Newbury.

 

 

Does anyone know what those bobbles are in the middle of the tracks?

 

 

They are lateral resistance plates fitted to anchor the sleepers in the ballast to prevent the track buckling. They are required on sharp curves where continuously welded rail is provided.

 

Dundas is on the Westbury to Bath(ampton) line so not directly on the Newbury (Berks & Hants) like.

 

JP

Edited by Captain Pegg

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Just to add in this case I think the plates are also to transition the lateral stiffness into the short section of slab track that sits under the bridge. They seem to be closer spaced near to the bridge itself. I believe this work was done about five years ago while the Swindon to Bristol line was closed for electrification preparation. Probably done for gauge clearance purposes.

 

JP

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4 hours ago, 1st ade said:

It might just be the shadow but the pier looks offset towards the other side of the 'ole (possibly under the canal rather than under the towpath?)

 

Is there a suitable view from the other end? (or does that also rely on the vegetation clearance?)

The nearest view from public access is the far river bank, and you probably need to be 150m away - binoculars needed! I might try that this weekend

 

I had assumed the pier was central, but it may not be. There is a "towpath" on both sides so the bank to be retained on the other side is just as large, however it is on the inside of a sharp bend and they may have, for reasons I am not aware of, decided that the far bank needed more support.

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17 minutes ago, Tim Lewis said:

Interesting timelapse video of the track lowering here to allow the route to be used as a diversionary route for freight trains in the future:

 

https://www.youtube.com/watch?v=tFz2CnCwOk4

Which I think confirms the construction is symmetrical although it’s not absolutely clear on first viewing.

 

Historical research can sometimes try too hard to find a reason for things. My guess in this case is that it is aesthetic given the location. The slender stone arch hides a chunky brick structure. Rather like the eastern portal of the nearby Box Tunnel.

 

JP

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14 minutes ago, Captain Pegg said:

Which I think confirms the construction is symmetrical although it’s not absolutely clear on first viewing.

 

Historical research can sometimes try too hard to find a reason for things. My guess in this case is that it is aesthetic given the location. The slender stone arch hides a chunky brick structure. Rather like the eastern portal of the nearby Box Tunnel.

 

JP

That's my hypothesis too - coupled with the a slender arch not being practical for the whole structure

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2 hours ago, magpie patrick said:

That's my hypothesis too - coupled with the a slender arch not being practical for the whole structure

Indeed it wouldn’t but it would probably have been more economical to finish the job in the same construction as the main body of the bridge. 

 

JP

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1 hour ago, Captain Pegg said:

Indeed it wouldn’t but it would probably have been more economical to finish the job in the same construction as the main body of the bridge. 

 

JP

And therein lies the difference between 1800 and 2019...

 

1800 - it'll look better if... let's do it

 

2019 - it'll look better if... stuff that, it'll cost

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19 hours ago, 1st ade said:

And therein lies the difference between 1800 and 2019...

 

1800 - it'll look better if... let's do it

 

2019 - it'll look better if... stuff that, it'll cost

Indeed, but there are things we can do that they couldn't - this picture is one half of Ynysbwllog aqueduct (Neath Canal)being lowered into place - single girder nearly 50 metres long, more than the four Dundas spans (one river, two flood reliefe/accomodation, and the railway) combined

 

Neath Aqueduct.jpg

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If the original canal builders were so oblivious to economy, how come they built humpy bridges? Surely, being shorter*, they cost less to construct.

 

 

 

* than bridges which were not humpy, of course.

Edited by Athy

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2 hours ago, Athy said:

If the original canal builders were so oblivious to economy, how come they built humpy bridges? Surely, being shorter*, they cost less to construct.

 

 

 

* than bridges which were not humpy, of course.

And therein hangs a tale!

 

Certainly round here the high profile structures are pretty whilst others are not so well finished - we do have the dubious advantage of Bath Stone being the local building material which helps on the aesthetics (dubious as it's not the easiest of stone to build with - it has to be laid the same way as it came out of the ground)  

Not just canals either - go look round the back of things like the Royal Crescent and realise the grandeur is only facade deep.

Edited by Athy

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I discovered something similar when I worked in an office in Park Crescent near Euston Station some years ago. Behind the elegant Nash facade, the buildings had been poorly constructed, to the extent that the ones  which had not actually been bombed were knocked down before they fell down. Only the frontage was preserved. 

Edited by Athy

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Although the majority of canals were built on the cheap, the materials used were more sustainable, making maintenance more economic. The skills of craftsmen were higher then, and their values seem to have ensured that they made the best within the money available. Interestingly, concrete was used as early as the 1820s, and possibly before, for the foundations of some locks in France, though brick or stone could be used for covering the walls. 

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22 hours ago, 1st ade said:

And therein lies the difference between 1800 and 2019...

Lest we forget, as we so often do, Britain was then immensely rich as a result of a massive trade surplus and a huge empire made possible by ruling the waves - and indulging in some old fashioned, now "dubious" practices. ;)

 

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Just now, Sea Dog said:

Lest we forget, as we so often do, Britain was then immensely rich as a result of a massive trade surplus and a huge empire made possible by ruling the waves - and indulging in some old fashioned, now "dubious" practices. ;)

 

....like making a profit, which so few U.K. businesses seem able to do nowadays unless they sell hamburgers and pizzas.

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4 hours ago, Athy said:

If the original canal builders were so oblivious to economy, how come they built humpy bridges? Surely, being shorter*, they cost less to construct.

 

 

 

* than bridges which were not humpy, of course.

Yes, they did build the bridges humpy to keep costs down - an extreme example below (Lockgate bridge - lower Frankton)

106-lockgate-bridge.jpg

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Hump back bridges were actually comparatively expensive to build, while swing bridges were much cheaper. On the L&LC, originally almost all the bridges between Liverpool and Wigan were swing bridges for this reason.

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