Latest video explaining progress on site:
I wonder if there’ll be a longer version in news programmes later today, that seemed a bit short…Latest video explaining progress on site:
Absolutely - it's much better PR in my view (especially in these days of hyperactive speculation on social media) to be clear and transparent.Kudos to Stuart - refreshing honesty and frankness. Looks like great progress.
Looked fine to me. Short and snappy, and nice to see the rowers going under the bridge too!I wonder if there’ll be a longer version in news programmes later today, that seemed a bit short…
Absolutely- perfect length for 99.5% of the population.Looked fine to me. Short and snappy, and nice to see the rowers going under the bridge too!
Yes, OK, but we technocrats would like more details. For example, why so many temporary piles? How big are they, and how long? Were they driven or bored? How far down do they go before ground of an adequate bearing strength was found? Will they be filled? - and if so what with? What will the supporting beam be like? and - and - and . . .Absolutely- perfect length for 99.5% of the population.
Given the time constraints, I'd rather they get on with doing it. Maybe we'll get a nice long technical video with a very exhausted Stuart Calvert after June 10th.Yes, OK, but we technocrats would like more details. For example, why so many temporary piles? How big are they, and how long? Were they driven or bored? How far down do they go before ground of an adequate bearing strength was found? Will they be filled? - and if so what with? What will the supporting beam be like? and - and - and . . .
Well from the video, it looks like 12 round driven piles on each side. Given the number I’d hope they wouldn’t need to fill them as well.Yes, OK, but we technocrats would like more details. For example, why so many temporary piles? How big are they, and how long? Were they driven or bored? How far down do they go before ground of an adequate bearing strength was found? Will they be filled? - and if so what with? What will the supporting beam be like? and - and - and . . .
Many thanks for posting the link.https://www.bbc.co.uk/iplayer/episode/m001lf5y/south-today-evening-news-26042023 is yesterday evening's South Today, the report on the viaduct starts at 4:18. There's not a huge amount more than in the version on Twitter.
I stress that I'm not involved in this project at all, and thus my answers here are pure educated guesses, but I am a railway engineer and a chartered member of ICE, so here's my thoughts...Yes, OK, but we technocrats would like more details. For example, why so many temporary piles? How big are they, and how long? Were they driven or bored? How far down do they go before ground of an adequate bearing strength was found? Will they be filled? - and if so what with? What will the supporting beam be like? and - and - and . . .
Given the timescales that this job was done in, the calculations to work out how many piles would be genuinely needed would take too long, and would involve some pretty big assumptions about the ground type anyway. If this were a project on a normal timescale you'd do some robust ground investigation, but there's no time for that here, plus the ground is known to be settling/moving/substandard because, well...why so many temporary piles
Almost certainly 660mm diameter as this was one of the most common pile types used on the electrification project, and thus is probably what was in a store somewhere. The piles look very much like leftover electrification foundation piles - look at the tops - those are screw fixings for OLE mast brackets.How big are they, and how long?
Almost certainly vibrated or hammered (or a bit of both) down. You're putting these into a river bed so you really don't want to be boring or augering if you don't have to.Were they driven or bored
The designers probably only had a very rough idea of what they could expect for that, hence my above assumption of driving to a force rather than a depth.How far down do they go before ground of an adequate bearing strength was found?
Unlikely. If they were filled they would be filled with concrete, which would make removal much harder. Given these are temporary, almost certainly with the river authority demanding a removable solution, you want them to be able to be removed fairly easily, or, if they refuse to come back out again, able to be cut off at the river bed.Will they be filled?
My best guess would be something like the 'superprop' from mabey: https://www.mabeyhire.co.uk/MabeyHi...ropping-and-Jacking-Brochure-web.pdf?ext=.pdfWhat will the supporting beam be like
Almost certainly vibrated or hammered (or a bit of both) down.
The span will be being held up by the temporary structure in the river, won't it?With this lack of certainty I wonder if they need to take precautions in case the span starts settling back during the abutment work. For example they could leave the middle or the sides of the existing one in place while they build the first part of the new one, so there is always something to catch the span if it drops.
What I've seen in the background of those videos, mounted on a big digger, is a Movax side-grip vibratory pile driver (SG series). And TMS list one as part of their equipment for piling contracts, though call it SPH-75 (and they have hired in excavators). I think that's an outdated model name for the same thing, Movax having decided to make a clearer distinction between their side-grip vibrators and their pile hammers.There was a lot of hammering, audible for miles around.
That's a good update, succinct and informative. Good to see it coming from an engineer (I think) rather than PR people.More news on Twitter: https://twitter.com/networkrailwest/status/1651886169997692929?ref_src=twsrc^tfw
Piles are down 15 metres I think he said.
In view of the preceding post mentioning uncertainty about the ground conditions under the temporary structure, I wondered if there was a risk of it starting to sink under the weight of the span.The span will be being held up by the temporary structure in the river, won't it?
I would have thought the numerous piles under the temporary structure provide much better support than anything under the original abutment. However, there will be jacks between the pile-capping platform and the bridge span, so these can be extended or supplemented by chocks if there's settlement and if it isn't too disastrous.In view of the preceding post mentioning uncertainty about the ground conditions under the temporary structure, I wondered if there was a risk of it starting to sink under the weight of the span.
I would have thought the numerous piles under the temporary structure provide much better support than anything under the original abutment. However, there will be jacks between the pile-capping platform and the bridge span, so these can be extended or supplemented by chocks if there's settlement and if it isn't too disastrous.
They have gone to the trouble of providing a service, and yet only calling at Appleford in one direction. That's bad, isn't it? Why can't they provide a proper service? Is it because they are going to use one track to give rail access to the works, do you think? There will be a lot of spoil coming out when the abutment is demolished, and it could go by rail. But where to?From 2nd May GWR will start running shuttles between Oxford and Radley, and between Didcot and Culham. It will be pilotman working at both ends, using the down line to and from Radley, and the up line to and from Culham. Trains will not be able to call at Appleford in the Culham direction, due to the platform being on the offside and no DOO equipment fitted, but will be able to call in the Didcot direction.
No crossover, I would imagine, and I don’t think the “Kletterweiche” would go down very well with the safety authorities!They have gone to the trouble of providing a service, and yet only calling at Appleford in one direction. That's bad, isn't it? Why can't they provide a proper service? Is it because they are going to use one track to give rail access to the works, do you think? There will be a lot of spoil coming out when the abutment is demolished, and it could go by rail. But where to?
The shuttles have to go out and back on the same track, so whichever one they use one of the Appleford calls will be stopping in the "wrong" direction for that platform.They have gone to the trouble of providing a service, and yet only calling at Appleford in one direction. That's bad, isn't it? Why can't they provide a proper service? Is it because they are going to use one track to give rail access to the works, do you think? There will be a lot of spoil coming out when the abutment is demolished, and it could go by rail. But where to?
I think the implication from at least one of the videos with NR was that spoil was going to be removed by road.They have gone to the trouble of providing a service, and yet only calling at Appleford in one direction. That's bad, isn't it? Why can't they provide a proper service? Is it because they are going to use one track to give rail access to the works, do you think? There will be a lot of spoil coming out when the abutment is demolished, and it could go by rail. But where to?
Digging back the embankment a few metres from the abutment, the spoil would only fill a handful of wagons. And it would have to be got along and up the embankment and into the train somehow. Far easier just to bring a truck up near the site, drop the spoil straight from the digger, and swap trucks when full.I think the implication from at least one of the videos with NR was that spoil was going to be removed by road.
Could they not find some process involving a competent person on the platform to allow the train to safely arrive/depart?No crossover, I would imagine, and I don’t think the “Kletterweiche” would go down very well with the safety authorities!
For a station which sees, at the very most about 25 passengers a day?Could they not find some process involving a competent person on the platform to allow the train to safely arrive/depart?