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Railway bridge repairs under way to link Gloucestershire canals


Alan de Enfield

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24 minutes ago, Cas446 said:

 

Any idea of the timetable for lifting in the new bridge sections?

See timeline below.

 

CCT have specifically asked people to stay away and be content to share the activity from comfort of their arm chairs. The Viewing arrangements around the site are very restricted and pretty much limited to the nearby Ocean Swing Bridge which needs to be kept clear fro local access. CCT will be publishing lots of material in the coming days

OceanActivityTimelineFINAL2.pdf

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2 hours ago, Captain Pegg said:

ETA - I guess it's possible the GSM-R base stations have fixed links between them, the wireless bit being the communication with the train.

AIUI they do, usually fibre, plus the base stations need power.  Microwave type (line of sight) inter cell links are possible  but practical railway topography means they don't always suit.

N

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7 hours ago, Up-Side-Down said:

See timeline below.

 

CCT have specifically asked people to stay away and be content to share the activity from comfort of their arm chairs. The Viewing arrangements around the site are very restricted and pretty much limited to the nearby Ocean Swing Bridge which needs to be kept clear fro local access. CCT will be publishing lots of material in the coming days

OceanActivityTimelineFINAL2.pdf 380.5 kB · 17 downloads

They are fractionally behind by the looks but not far. 
Re local access the Ocean swingbridge is narrow and there are around 10 properties that  need access so it’s not causing much issue with these viewers. Vehicles have to go very slowly anyway as the Lane is slow going with potholes. There were 2 people there today, more on the 26th as per usual Boxing Day walking tradition.
Looks like the main lifting will be overnight and tomorrow.  
Appreciate the CCT need to say such things but it’s a not one to miss seeing over this week IMHO. 

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On 25/12/2021 at 23:26, Stroudwater1 said:

I think it was more along the lines of oh xxxt we missed out a decimal point in our structural calculations tbh

You could well be right:- there have been criticisms  in the railway journals  about the hopelessly over-specified concrete foundations for the catenary masts of the Western Region electrification, which one contributor said were of a size that was more appropriate  for mooring bollards for very large cruise ships!

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13 hours ago, Ronaldo47 said:

You could well be right:- there have been criticisms  in the railway journals  about the hopelessly over-specified concrete foundations for the catenary masts of the Western Region electrification, which one contributor said were of a size that was more appropriate  for mooring bollards for very large cruise ships!

 

Possibly inspired forward planning for when global warming causes the sea levels to rise. 🤔🤣

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1 hour ago, cuthound said:

 

Possibly inspired forward planning for when global warming causes the sea levels to rise. 🤔🤣

 

The specification requires much higher levels of reliability than previous schemes and that is after taking into account climate change - wind speed being the key issue in this instance. That's a product of the political environment between now and a generation ago which results in the whole thing being very intrusive and cumbersome compared to what you will see on the WCML in Amington, which is a 60+ year only design for which there almost certainly were no reliability targets in the design specification. The foundations won't be over-engineered, they will simply reflect the loads placed upon them by the superstructures. I can't help but wonder if those supposedly commentating on such things appreciate that the GWML scheme makes a lot of use of twin track cantilevers which by nature require bigger foundations than portal structures. 

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7 hours ago, Captain Pegg said:

 

The specification requires much higher levels of reliability than previous schemes and that is after taking into account climate change - wind speed being the key issue in this instance. That's a product of the political environment between now and a generation ago which results in the whole thing being very intrusive and cumbersome compared to what you will see on the WCML in Amington, which is a 60+ year only design for which there almost certainly were no reliability targets in the design specification. The foundations won't be over-engineered, they will simply reflect the loads placed upon them by the superstructures. I can't help but wonder if those supposedly commentating on such things appreciate that the GWML scheme makes a lot of use of twin track cantilevers which by nature require bigger foundations than portal structures. 

I just checked my back numbers of Modern Railways (April and May 2021). The trouble with the Great Western electrification initially arose due to erroneous assumptions as to soil strength (proved by subsequent actual tests on real embankments), resulting in the use of steel piles 2' diameter that in some cases were  11 to 15 metres deep  (that's just the below-ground part) that were too big and heavy for the equipment that had originally been specified  to install them.  Subsequent calculations halved the necessary maximum depth to 7.5 metres. Piling was supposed to have been easier, faster,  and cheaper to install than poured concrete foundations, but in practice was  was none of them. In the light of a study by the University of Southampton, satisfactory shallower piles have been employed on subsequent electrification schemes where piling was preferable, otherwise   concrete foundations  typically  1 to 2 metres deep. 

Edited by Ronaldo47
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8 hours ago, Stroudwater1 said:

Looking like it’s pretty near done for the bridge in order to refill and return the line back. 
 

F1EE81FB-E7E8-4826-859B-273B7A279592.jpeg.8e0c37ade59a0ba9cc4a3003718e7f9a.jpeg

 

Plenty to do around still. The towpath isn’t due to be reopened until March. 

 

Plenty to tip now

 

07CACD51-19F4-453E-B9B2-20196DCE4EF7.jpeg.335ae330a8d45f645aba2ead3c0e46dc.jpeg
 

CF021A58-4ED4-42C3-B8DB-BD46D9819416.jpeg.e7cf5ba67743e6e6de74cd04f2deaa34.jpeg

 

Confirms my outsiders observation that a typical construction project time scale looks like this:

Installing temporary access roads, storage compounds, cabins, fencing and other elf'n'safety stuff - 20%

Moving piles of dirt from one place to another and back again, several times with diggers - 30%

Actual construction - 1%

More moving piles of dirt from one place to another and back again several times with diggers - 29%

Removing temporary access roads, storage compounds, cabins, fencing and other elf'n'safety stuff. 20%.

 

Edited by Jen-in-Wellies
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8 hours ago, Ronaldo47 said:

I just checked my back numbers of Modern Railways (April and May 2021). The trouble with the Great Western electrification initially arose due to erroneous assumptions as to soil strength (proved by subsequent actual tests on real embankments), resulting in the use of steel piles 2' diameter that in some cases were  11 to 15 metres deep  (that's just the below-ground part) that were too big and heavy for the equipment that had originally been specified  to install them.  Subsequent calculations halved the necessary maximum depth to 7.5 metres. Piling was supposed to have been easier, faster,  and cheaper to install than poured concrete foundations, but in practice was  was none of them. In the light of a study by the University of Southampton, satisfactory shallower piles have been employed on subsequent electrification schemes where piling was preferable, otherwise   concrete foundations  typically  1 to 2 metres deep. 

 

So no wrong calculations then. There's good provenance for problems with assumptions on soil strength on the GWML, started by Brunel.

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2 hours ago, Jen-in-Wellies said:

Installing temporary access roads, storage compounds, cabins, fencing and other elf'n'safety stuff - 20%

 

When they built the new bridge over the railway at Kintbury, they spent a whole year on this bit, and about two weeks actually building the bridge. 

 

Granted, much of the year prepping comprised fencing off the access road land and scouting it for newts, daily. Honest, I had a chat with the bloke sub-contracted to do this! 

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4 minutes ago, MtB said:

and scouting it for newts, daily. Honest, I had a chat with the bloke sub-contracted to do this! 

I know some one who made a job out of doing bat surveys prior to construction work. Another creature under legal protection.

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15 minutes ago, Tacet said:

The real money is in not finding any

 

Similarly with newts but in reverse. If you are fighting development plans on a greenfield site, commission a newt survey. Chances of the ultra-rare and protected great crested newt being found are 100%, if you use the right newt survey company. 

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