Nuneham Viaduct shut - Didcot- Oxford

[randyrippley]

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

Looks like a water main.
If that's been leaking it could easily create a large void capable of causing this damage

 

[birchesgreen]

Really? Train to Didcot and RRB to Oxford. Not all that adventurous!

Dude you should have seen the queue at Didcot Parkway on friday, i thought the Beatles had reformed.

 

[swt_passenger]

Looks like a water main.
If that's been leaking it could easily create a large void capable of causing this damage

Isn’t that likely to be one of the first things they’d have checked, way back when the problem started?

 

[randyrippley]

Isn’t that likely to be one of the first things they’d have checked, way back when the problem started?

may not have been the original problem, but if the pipe started leaking you could get a void in a few days

 

[Mcr Warrior]

Dude you should have seen the queue at Didcot Parkway on friday, i thought the Beatles had reformed.

Doesn't sound too good, to be fair. How's it compare with Twyford when the Henley Regatta's on?

 

[CHESHIRECAT]

Pathfinder charter still shows as running on Friday!

 

[zwk500]

Pathfinder charter still shows as running on Friday!

Presumably Pathfinder are still working out which half should get the train and which half will have to be bussed/given alternative travel to Birmingham.

 

[jfollows]

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

NRE updated at 08:13 (https://www.nationalrail.co.uk/service_disruptions/321909.aspx):

Urgent repairs to a bridge between Didcot Parkway and Oxford are taking place. As a result of this, trains are currently unable to run between these stations.

Disruption between Reading and Oxford is expected until at least the end of the day on Wednesday 31 May.

 

[jimm]

Looks like a water main.
If that's been leaking it could easily create a large void capable of causing this damage

There is a much larger and definitely leaky source of water in the vicinity of this structure. It is called the River Thames.

The photo by crablab in post 426 gives a good idea of just how soggy ground conditions can get in the vicinity of this bridge in autumn, winter and early spring (as was obvious to anyone looking out of the window on a passing train).

This time round, of course, it followed an extremely hot, dry summer when the river levels were very low, then a wet autumn, then a dry January and February, followed by a very wet March.

All those changes of conditions likely contributed to the sinking of the abutment suddenly accelerating. If it was sitting on solid rock, there would not be a problem.

 

[InOban]

The latest NR video states that it will be several weeks, and that's for a temporary fix.

 

[quantinghome]

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).

The railway has been here for more than one hundred years. In that time the weight of the embankment and abutment will have consolidated the underlying ground and increased its stiffness. Foundation movement would have greatest immediately after the bridge was built and would gradually decline until it reached a stable condition:



Something must have happened more recently to initiate the movement we have seen over the past year.

 

[Hellzapoppin]

Now I'm not a civil engineer but could it be that the abutment isn't sinking but the embankment behind is slipping and taking it with it ?

 

[SouthEastBuses]

Is it true that the Didcot to Oxford railway line will be closed until 31 May? (That's what National Rail Enquiries claims)

 

[jfollows]

Is it true that the Didcot to Oxford railway line will be closed until 31 May? (That's what National Rail Enquiries claims)

Others posting here have said that it will probably be later than that when the line re-opens.

 

[zwk500]

Is it true that the Didcot to Oxford railway line will be closed until 31 May? (That's what National Rail Enquiries claims)

And beyond - 9th June has been reported as the industry comms date.

 

[brad465]

Is it true that the Didcot to Oxford railway line will be closed until 31 May? (That's what National Rail Enquiries claims)

The disruption is now also considered major/red on the website, something it wasn't considered last week IIRC.

 

[12LDA28C]

A recent post by a senior NR engineer suggests the foundations for the bridge piers are pads and the current issue has been caused by scouring over many years, made worse by subsidence. Underpinning is required in the first instance as a short-term solution prior to full replacement.

 

[BrianW]

Now I'm not a civil engineer but could it be that the abutment isn't sinking but the embankment behind is slipping and taking it with it ?

I'm not a civil engineer either, but I do recall the 'heatwave' of 1976 and the consequent foundation 'issues' especially related to clay shrinkage. I'm sure the rail engineers and geological technicians will be familiar. Just by 'Googling' I found this:

https://www.itrc.org.uk/wp-content/PDFs/Soil-movement-impacts-UK-infrastructure.pdf

Hoping some Forumites may find this of some interest. This won't be the only location of concern into the future. I'm recalling Carmont again.

 

[GRALISTAIR]

Is it true that the Didcot to Oxford railway line will be closed until 31 May? (That's what National Rail Enquiries claims)

it says at least

And beyond - 9th June has been reported as the industry comms date.

indeed

 

[Class 170101]

I'm not a civil engineer either, but I do recall the 'heatwave' of 1976 and the consequent foundation 'issues' especially related to clay shrinkage. I'm sure the rail engineers and geological technicians will be familiar. Just by 'Googling' I found this:

https://www.itrc.org.uk/wp-content/PDFs/Soil-movement-impacts-UK-infrastructure.pdf

Hoping some Forumites may find this of some interest. This won't be the only location of concern into the future. I'm recalling Carmont again.

Clay shrinkage, try a more recent example liike Spring and Summer 2022, never mind summer 1976.

 

[BrianW]

it says at least



indeed

Many (most?) 'issues' get worse the more they are looked at- more (and worse and possibly more extensive) problems are identified.
Optimism bias. Would folk prefer to be told the line will be closed until Christmas and just maybe be relieved when the work is finished early?

 

[Class 170101]

Pathfinder charter still shows as running on Friday!

Presumably Pathfinder are still working out which half should get the train and which half will have to be bussed/given alternative travel to Birmingham.

Or from Didcot via Acton West / Acton Wells, Neasden, Denham and Oxford then reverse but a very long way round

 

[SouthEastBuses]

Damn it! Now it means I have to wake up really early and get an S6 to Swindon or X2/X32 to Didcot Parkway when I fancy doing trips to South Wales or the West Country! Adding so much journey time for what I was hoping it would be a short period. I am aware about the rail rep but with them likely to be extremely busy I think it's better if I get on local buses instead.

I would hope that the repair to this bridge can be used as an excuse to restart electrification between Didcot Parkway and Oxford (combined with the new platform 5 at Oxford). But sadly, I fear it will be too good to be true

 

[The Planner]

Damn it! Now it means I have to wake up really early and get an S6 to Swindon or X2/X32 to Didcot Parkway when I fancy doing trips to South Wales or the West Country!

I would hope that the repair to this bridge can be used as an excuse to restart electrification between Didcot Parkway and Oxford (combined with the new platform 5 at Oxford). But sadly, I fear it will be too good to be true

Why would it? you don't have the resource milling about waiting for a call like the A Team to come and do something. The maintainer will likely get in and do some other jobs that need catching up on, you potentially could even get a track relay, drainage or high output ballast job in, but wires, no chance.

 

[quantinghome]

Clay shrinkage, try a more recent example liike Spring and Summer 2022, never mind summer 1976.

Seasonal changes in water level would produce a shrink/swell cycle in some types of clay, which would have impacts on track alignment. However, I can't see how that could cause the ongoing one-way deflections we are seeing on the abutment.

Given the abutment is known to have been a problem for some time, there will doubtless be teams of engineers investigating it who have much more detailed information so I'll refrain from speculating.

 

[SouthEastBuses]

Why would it? you don't have the resource milling about waiting for a call like the A Team to come and do something. The maintainer will likely get in and do some other jobs that need catching up on, you potentially could even get a track relay, drainage or high output ballast job in, but wires, no chance.

As I suspected

 

[GRALISTAIR]

Many (most?) 'issues' get worse the more they are looked at- more (and worse and possibly more extensive) problems are identified.
Optimism bias. Would folk prefer to be told the line will be closed until Christmas and just maybe be relieved when the work is finished early?

Well I certainly prefer to under-promise and over-deliver.

 

[zwk500]

I would hope that the repair to this bridge can be used as an excuse to restart electrification between Didcot Parkway and Oxford (combined with the new platform 5 at Oxford). But sadly, I fear it will be too good to be true

With respect, no sensible investment management would permit a decision process that resultant in electrification because of a bridge failure.

 

[LNW-GW Joint]

As I suspected

Well, Network Rail sold off all the surplus steelwork they had bought for Oxford/Bath electrification.
They also stood down the project teams (some now at work on the South Wales Metro) and it would take much longer than 3 months (or whatever) to mobilise them again at Oxford.
NR has also lost the authority to do the work until the DfT/Treasury relents, which it won't in the forseeable future.
I also suspect the electrification design would have to change to reduce the cost from that of the original scheme.
Meanwhile the class 80x bi-modes don't need wires to serve those places (and others).

 

[Snow1964]

The Independent has now reported the story, and ignoring the headline which refers to it as a wobbly bridge

A team of engineers from Network Rail spent the weekend examining the structure.

On the afternoon of Easter Monday , a spokesperson for the infrastructure provider said: “Network Rail has confirmed that it is now working to install a temporary structure that will stabilise the viaduct at Nuneham in Oxfordshire in order for trains to run again between Didcot Parkway and Oxford by 10 June.

“Engineers have been working round the clock since the line was closed for safety concerns on 4 April and are now able to confirm this timescale.

So looking like a timescale of by 10th June is now confirmed

Main rail line to close until June due to a wobbly bridge

Passengers between the north of England and the South Coast are being advised to travel via Bristol or London instead

www.independent.co.uk