Nuneham Viaduct shut - Didcot- Oxford

[Signal Head]

Also, stepping through historic aerial imagery on Google Earth, Bedwyn's reversing siding seems to have been extended by a few metres at the country end between 2017 and 2020, with a panel of concrete- sleepered track, a nice new bufferstop, and a small diversion of the footpath crossing the line there to suit.

It was. Specifically to take a 5 car IET.

On Google Maps I make the reversing siding 140m from Stop block to dolly, you can knock 2m off for stopping distance at the buffers, and probably 5m off for standing clear of the signal, so 132m. 5x25 = 125m, so I'd only have to be out by 7m (easy enough using Google Maps) for the 5-Car unit to not fit. It's tight, but possible, but as ever there's usually a reason why Control doesn't 'just f***ing do it' without checking first.

I generally find Google maps measurements to be highly accurate, and certainly no where near giving a 7m error over 140m.

I've used the feature to measure for scheme plans, either as a double check or when I'm waiting for 'proper' survey data. I've never found any noticeable discrepancies when I've corresponded it with survey data later on.

 

[Falcon1200]

Whacking the schedules in and taking the delay minutes by the looks of it, 1G27 is going to be late.

At this point probably needs to run no matter what or it will have knock on effects to the supply chain.

Indeed. It might be that there was simply no valid path available, but Control (if it was a VSTP) or the Train Planners were told by a higher level that the train must run regardless.

 

[Meerkat]

Network Rail Western have posted a couple of pictures on Twitter (https://twitter.com/networkrailwest/status/1644354347986481152), along with a post with not much more information than that they are working to find a solution and will provide more information next week.

The picture shows possibly the length of one or two track panels have been removed on the approach to the bridge on one line.

As these are copyright Network Rail, I haven't just lifted them, but they are availble at https://pbs.twimg.com/media/FtHTc2SXwAUwYDo?format=jpg&name=large and https://pbs.twimg.com/media/FtHThN1XsAA9ygp?format=jpg&name=medium.

Would the engineers be able to offer confidence that the bridge wont collapse further? Bit surprised not to see a rescue boat in the water for work on an unstable bridge?

 

[edwin_m]

Would the engineers be able to offer confidence that the bridge wont collapse further? Bit surprised not to see a rescue boat in the water for work on an unstable bridge?

The abutment has been sinking gradually, and also moving back as it tips away from the river. The only chance of a sudden collapse is if the backward movement is enough that the span drops off its support at one end or the other. There should be plenty of warning for anything like that, and there will be monitoring in place.

 

[norbitonflyer]

No problem. I had to cycle down a very muddy and significantly flooded path to get them!

The land around is extremely waterlogged and flooded, even a week after the big rainstorm. The Thames is still over the top of its banks in some areas along here (including the path!) and is fast flowing.

Given the state of the bridge, are we in a Hammersmith situation, or are the river and towpath still open under it?

 

[crablab]

Given the state of the bridge, are we in a Hammersmith situation, or are the river and towpath still open under it?

Still open (well, if you ignore the flooding). It is only the far side embankment (and brickwork) that has failed.

 

[norbitonflyer]

Still open (well, if you ignore the flooding). It is only the far side embankment (and brickwork) that has failed.

Found this notice from the Environment Agency after posting

As you say, the towpath is on opposite (north) side to the failed abutment.

 

[Snow1964]

The abutment has been sinking gradually, and also moving back as it tips away from the river. The only chance of a sudden collapse is if the backward movement is enough that the span drops off its support at one end or the other. There should be plenty of warning for anything like that, and there will be monitoring in place.

The sinking pier is an end of a bridge, so has an embankment behind it. Not likely to suddenly push an embankment out of the way.

The bridge sits on bearings each end, so just a downwards force due to gravity*. Not like a shallow arch bridge where the forces are pushing the piers outwards.

* strictly get a side force from thermal expansion, and trains accelerating and braking. But think we can ignore that here as relatively tiny.

 

[QueensCurve]

You are absolutely correct. I had forgotten all about that.

Lamington was impressive, but if I remember they kept the original deck having rebuilt one pier and installed new bearings.

 

[swt_passenger]

Lamington was impressive, but if I remember they kept the original deck having rebuilt one pier and installed new bearings.

Post #345 in this thread has links to details of exactly what they did, and yes the decks remained in place, having been realigned.

 

[ian1944]

For comparison, the Ness bridge in Inverness was washed away in February 1989 and re-opened in May 1990. There seems to have been no suggestion of gradual movement previously, the collapse was from just the horizontal force of water.

 

[edwin_m]

The sinking pier is an end of a bridge, so has an embankment behind it. Not likely to suddenly push an embankment out of the way.

The bridge sits on bearings each end, so just a downwards force due to gravity*. Not like a shallow arch bridge where the forces are pushing the piers outwards.

* strictly get a side force from thermal expansion, and trains accelerating and braking. But think we can ignore that here as relatively tiny.

A photo posted a couple of pages back shows that that's moreorless what it's been doing. It seems to me that the ground beneath the embankment is giving way (probably this was just natural ground with no treatment to increase its stiffness before the embankment was placed on top). The embankment is therefore sinking and the abutment, probably also resting on the same unstable ground, is tipping backwards into the void. This means that the supports of the bridge span bearings are getting further apart, with the possibility of the span dropping off one of them at some point (but plenty of warning before that happens).

 

[daodao]

Peter Hitchens has made some comments about this closure in his "Mail on Sunday" blog, as it affects him personally.

My daily train journey to London has become a nightmare of diversions and replacement buses for weeks, possibly months to come – because a rail bridge over the Thames is no longer safe. Railway rumour says this is because of a huge crack in the brickwork. Trains had been crossing it at walking pace for weeks. This is not some lightly-used branch line. In normal times dozens of heavy, fast passenger and goods trains rumble across it every day.

The present bridge, steel coathangers on brick piers, is about a century old. Part of the brick structure dates from 1856. In many years of travelling, I have never seen anybody doing major work on it. Network Rail, who are now in charge of looking after it, are vague about when it was last properly maintained. They told me it ‘has undergone regular intrusive and visual inspections since a stepped-up inspection regime was implemented in 2012’. But when asked how regular they couldn’t say. They told me monitoring equipment was installed five years ago, which rather suggests they knew something was up. They plead as an excuse that this has been the wettest March for 40 years. I suspect that much of this country relies on the high standards and hard work of long-dead men, who designed and built thousands of such bridges so well we thought they would last forever. Well, they don’t.

Governments are wildly keen on huge, grand projects to build high-speed lines and new motorways. But what about the basic, unflashy work of maintenance – which all house-owners know is so essential? I suspect that if the railways were still nationalised, this would not have happened.

Mail Online - Peter Hitchens blog

 

[LNW-GW Joint]

Maybe Peter Hitchins can't remember the Penmanshiel tunnel collapse in 1979, where the ECML was closed for 5 months while a new non-tunnel route was constructed.
I also seem to recall BR had a huge backlog of maintenance work outstanding at the end of its tenure, and suffered from "lack of investment for decades".
He also doesn't seem to realise the present owner/maintainer, Network Rail, has been fully nationalised for almost a decade.

 

[JamesT]

Maybe Peter Hitchins can't remember the Penmanshiel tunnel collapse in 1979, where the ECML was closed for 5 months while a new non-tunnel route was constructed.
I also seem to recall BR had a huge backlog of maintenance work outstanding at the end of its tenure, and suffered from "lack of investment for decades".
He also doesn't seem to realise the present owner/maintainer, Network Rail, has been fully nationalised for almost a decade.

Peter Hitchens is a professional contrarian, I think he ignores things that get in the way of his argument.

 

[zwk500]

Maybe Peter Hitchins can't remember the Penmanshiel tunnel collapse in 1979, where the ECML was closed for 5 months while a new non-tunnel route was constructed.

Wasn't the Penmanshiel collapse linked to the upgrade work rather than a long-term maintenance issue?

I also seem to recall BR had a huge backlog of maintenance work outstanding at the end of its tenure, and suffered from "lack of investment for decades".

Indeed, there's been maintenance backlogs since WW2 and the railway has, to tell the truth, never properly recovered. Sectorised BR and Railtrack weren't significantly different from NR's long-term position AIUI.

He also doesn't seem to realise the present owner/maintainer, Network Rail, has been fully nationalised for almost a decade.

It's an inconvenient fact for both sides, so they forget that NR is the 2nd biggest QUANGO in the land.

 

[Nicholas43]

I don't see how Network Rail, or any wizard subcontractor, could have 'maintained' the foundation of the now-tilting pier at the south end of the bridge.
There's currently an impressive lot of Balfour Beatty people building an impressively sturdy platform on the bank just downstream of the bridge, and another contractor with a van advertising that their big suction tube is the only safe way of digging.
While wishing to avoid forbidden speculation, it does seem fairly clear to me that Balfour Beatty are going to have to (1) install a temporary prop for the south end of the south span (2) build a stable new pier.

 

[hwl]

I don't see how Network Rail, or any wizard subcontractor, could have 'maintained' the foundation of the now-tilting pier at the south end of the bridge.
There's currently an impressive lot of Balfour Beatty people building an impressively sturdy platform on the bank just downstream of the bridge, and another contractor with a van advertising that their big suction tube is the only safe way of digging.
While wishing to avoid forbidden speculation, it does seem fairly clear to me that Balfour Beatty are going to have to (1) install a temporary prop for the south end of the south span (2) build a stable new pier.

They were gearing up for some work but it all started getting a lot worse very quickly.
From photos - The river retaining wall underneath the abutment and wing walls is cracked and bowing outwards into the river and there is erosion of the river bank downstream on the south side (this is where the movement of saturated material below ground level is occurring due to the weight of the railway formation above). The first thing needed (after removing some weight e.g track panels and ballast from the southern bridge decks and embankment) is to install a new longer retaining wall to prevent further movement. For a short term solution the existing abutment wall (seemingly intact unlike the wing walls) might be able to be reused with the bridge deck jacked up and spacers + new bearings added. the abutment wall and embankment behind it only appears to have been sinking for up to ~7m from the exposed space of the wall.

Is there any evidence in the photos that the abutment wall is tilting? There is plenty of evidence of sinking (along with the middle section of the embankment directly below the track behind it but none of rotation parallel to the track either towards the river or embankment. The more lightly loaded outer extents of the embankment has seemingly sunk far less than the heavier middle section resulting in the wing wall cracks and rotation inwards of the top surfaces of the embankment towards the ground level as the embankment core sinks.

Edit to add:
Some June 2022 Photos from Linked_in

The wing walls have at least 4 different type of bricks with an extensive repair and replacement history with about half the then current cracks replicating old repair lines. The sinking isn't new the rapid pace is.

 

[12LDA28C]

Peter Hitchens has made some comments about this closure in his "Mail on Sunday" blog, as it affects him personally.

Mail Online - Peter Hitchens blog

I've corrected his 'blog' for him, it now reads:

My daily train journey to London is now made on Chiltern Railways. End.

Doesn't have quite the same sense of hyperbole, too bad.

 

[XAM2175]

Wasn't the Penmanshiel collapse linked to the upgrade work rather than a long-term maintenance issue?

Not quite. The Railway Inspectorate report found that while the track-lowering works might have contributed to the collapse occurring at the precise moment it did, there was no failing attached either to the works or to the tunnel's maintenance in general. Rather, the tunnel was found near the point of collapse to be passing through an area of highly problematic geological conditions, the existence of which BR could not reasonably have been aware, and the complexity of which only became apparent during the excavation of the bypass cutting. Those conditions were judged to have made the tunnel "dangerously unstable", quite possibly for some time, and as such the collapse would likely have occurred at some time or another even if the works had not been undertaken.

 

[sonic2009]

Paul Clifton a transport correspondent for the BBC South has shared something he's gained from someone stating that closed until Mid June.

https://twitter.com/PaulCliftonBBC/status/1644964450611478528?s=19

I see ⁦@GWRHelp⁩ assumes the Didcot-Oxford line closed until the middle of June, because of damaged Nuneham viaduct over the Thames. Hugely disruptive for passengers on ⁦@CrossCountryUK⁩ and puts rail freight in an intolerable situation: more lorries on A34.

 

[InOban]

They were gearing up for some work but it all started getting a lot worse very quickly.
From photos - The river retaining wall underneath the abutment and wing walls is cracked and bowing outwards into the river and there is erosion of the river bank downstream on the south side (this is where the movement of saturated material below ground level is occurring due to the weight of the railway formation above). The first thing needed (after removing some weight e.g track panels and ballast from the southern bridge decks and embankment) is to install a new longer retaining wall to prevent further movement. For a short term solution the existing abutment wall (seemingly intact unlike the wing walls) might be able to be reused with the bridge deck jacked up and spacers + new bearings added. the abutment wall and embankment behind it only appears to have been sinking for up to ~7m from the exposed space of the wall.

Is there any evidence in the photos that the abutment wall is tilting? There is plenty of evidence of sinking (along with the middle section of the embankment directly below the track behind it but none of rotation parallel to the track either towards the river or embankment. The more lightly loaded outer extents of the embankment has seemingly sunk far less than the heavier middle section resulting in the wing wall cracks and rotation inwards of the top surfaces of the embankment towards the ground level as the embankment core sinks.

Edit to add:
Some June 2022 Photos from Linked_in

The wing walls have at least 4 different type of bricks with an extensive repair and replacement history with about half the then current cracks replicating old repair lines. The sinking isn't new the rapid pace is.

The first picture shows a large diameter steel pipe What's that about?

 

[zwk500]

Not quite. The Railway Inspectorate report found that while the track-lowering works might have contributed to the collapse occurring at the precise moment it did, there was no failing attached either to the works or to the tunnel's maintenance in general. Rather, the tunnel was found near the point of collapse to be passing through an area of highly problematic geological conditions, the existence of which BR could not reasonably have been aware, and the complexity of which only became apparent during the excavation of the bypass cutting. Those conditions were judged to have made the tunnel "dangerously unstable", quite possibly for some time, and as such the collapse would likely have occurred at some time or another even if the works had not been undertaken.

Thanks for the info!

 

[The Planner]

Paul Clifton a transport correspondent for the BBC South has shared something he's gained from someone stating that closed until Mid June.

Its well known that the block is until June 9th at the earliest.

 

[sonic2009]

Its well known that the block is until June 9th at the earliest.

Thanks, so why can't the clear information be given to the general public then. NRE still shows until 30th April.

 

[hwl]

Its well known that the block is until June 9th at the earliest.

Quite possibly picked up from this thread...

Thanks, so why can't the clear information be given to the general public then. NRE still shows until 30th April.

Probably will up updated after the weekend. At least 3 week in first instance is sensible but they pay be aiming to get a more refined interation of a date in June.

 

[swt_passenger]

The first picture shows a large diameter steel pipe What's that about?

It’s fairly common for utilities such as water or gas to ‘piggy back’ on river bridges such as this one. Most likely one or the other.

 

[InOban]

It’s fairly common for utilities such as water or gas to ‘piggy back’ on river bridges such as this one. Most likely one or the other.

It looked quite new and I wondered if work on it had destabilised the embankment.

 

[swt_passenger]

It looked quite new and I wondered if work on it had destabilised the embankment.

I think there‘s far more going on here than a problem with the embankment.

 

[crablab]

The first picture shows a large diameter steel pipe What's that about?

It's a water pipe. I don't have a photo but there is an ID tag attached to it stating that it belongs to "Oxford Water".