Black Bridge, Nuneham: southern abutment failure

[whole diary]

[stuving]

There's a lot of confusion over whether this is a bridge or a viaduct (and GWR^▸ (Great Western Railway) used to call it Newnham, as well). The replacement for the original timber structure had steel plate girders resting on six sets of columns (piers, in effect), spanning the river and the ground on the Oxford side. That was replaced in 1906 by the present bridge, and three "piers" were removed from the river and replaced by one pier, since the bowstring girders are longer. The next support was replaced by a pier of the same design, leaving three of the old spans and two "piers" as the viaduct part. Lots of details about that is this document, including how it was done (mostly closing one line at a time).

However, now that viaduct is made of three brick arches - as seen in this geograph photo. (I think getting to where that was taken was probably quite a struggle.) But I've no idea when that happened - and which bit is now subsiding?

[paul7575]

Ah, the photo that stuving has found shows there’s a few more areas that might be the failure site. The aerial photos don’t really give you any idea that’s there still some brick arch viaduct in use.

Paul

[eightonedee]

Now being featured on BBC^» (British Broadcasting Corporation - home page) local news - apparently closed for at least two weeks. Paul Clifton reporting - NR^» (Network Rail - home page) to make announcement tomorrow

[CyclingSid]

When I passed on Saturday, at walking speed, there was a haul road to the site and some people on/next to site.

At the moment I think the main problem will be the state of the river. River is above normal

https://check-for-flooding.service.gov.uk/station/7097 [NOTE: this is a live link so will change depending on when you see it]

and the current river conditions

Abingdon Lock to Culham Lock    Red Caution strong stream warning
Culham Lock to Clifton Lock    Red Caution strong stream warning

https://www.gov.uk/guidance/river-thames-current-river-conditions#current-river-conditions-updated-3-april-2023 which means

Strong stream warning board

When these red boards are displayed on lock gates, the Environment Agency advises users of all boats not to navigate. The strong flows make it difficult and dangerous.

[Richard Fairhurst]

Ah, the photo that stuving has found shows there’s a few more areas that might be the failure site. The aerial photos don’t really give you any idea that’s there still some brick arch viaduct in use.

Yes, on both sides, I think. You can get a bit more of a peek from below with Google Street View, which has the view from the Thames Path on it.

[BBM]

This was the main story just now on BBC^» (British Broadcasting Corporation - home page) South Today with Paul Clifton. There was some video showing that one of the two spans is definitely out of vertical alignment. He said that NR^» (Network Rail - home page) staff are currently not at the scene and there's no comment from the company as to the exact nature of the problem. He expects them to make a statement tomorrow.

[stuving]

Ah, the photo that stuving has found shows there’s a few more areas that might be the failure site. The aerial photos don’t really give you any idea that’s there still some brick arch viaduct in use.

Yes, on both sides, I think. You can get a bit more of a peek from below with Google Street View, which has the view from the Thames Path on it.

Ah, so it is not so inaccessible. You can also see the piers of the viaduct arches on satellite view - just, once you know where to look. But that is only on the north side, and it is the newest part of the structure, and the problems before 1906 were all in the river. So maybe when they went down "11 feet below the river bed to the Oxford clay" that wasn't enough.

[CyclingSid]

Paul Clifton an hour ago https://twitter.com/PaulCliftonBBC

[stuving]

What I see in those BBC^» (British Broadcasting Corporation - home page) pictures (however reliable that is) is that the transition pier on the north bank has dropped. That makes historical sense, if that bit was not seen as a problem in 1906, so its foundations don't go down as far as the one in the river bed. Since then, with the disturbance of having the viaduct rebuilt, and a heavier pier and bridge to support ...

I find it hard to believe that the water table that close to the river has changed much.

[paul7575]

GWR^▸ (Great Western Railway) has now been added to the list on the National Rail page mentioned earlier, about XC^▸ (Cross Country Trains (franchise)) ticket acceptance following the failed Nuneham bridge/viaduct…

Paul

[Electric train]

I find it hard to believe that the water table that close to the river has changed much.

There has been a lot of gravel extraction and subsequent land fill in the last few decades, I wonder if this has impacted the water table.

[stuving]

I have found one newspaper reference to the rebuilding of the viaduct, and that's from a "last year's work" summary in January 1931, and is as curt as: "the north end of Nuneham viaduct, Culham, [has been] reconstructed".

From the Thames Path, you can see that the arches piercing the pier on the north bank were filled in when that work was done. But there is no sign on distress in the pier itself, nor what little you can see of the arch attached to it. So maybe that isn't quite so likely as an explanation. You can also see the bearings of the bridge, which are not exactly sophisticated, and how the skew on the bridge complicates the one on the left (west) side.

[TaplowGreen]

Thoughts with all affected.

Cancellations to services between Reading and London Paddington

Due to a person hit by a train between Reading and London Paddington all lines are blocked.

Train services running to and from these stations may be cancelled or delayed. Disruption is expected until the end of the day.

[stuving]

I've now seen a picture on railforums that I think is of the west wing wall on the south bank, and this really is distressed. It's just at the very right of the BBC^» (British Broadcasting Corporation - home page)'s shots, and out of sight looked at from above. But you can see that the parapet pillar (supporting the fence rails) is decidedly wonky. A drop in that bearing would, of course, give the same angle at the mid-river pier. You can also see how deep the ballast bed on the bridge has got over the years! Do you think that was to compensate for this drop?

I do hope these guys have not become so specialised that NR^» (Network Rail - home page) have only got one wing-wall team.

[eightonedee]

Moderators - can I suggest that the Nuneham/Culham viaduct problem merits its own thread, rather than being split between two general delay threads as at present?