Great Western Coffee Shop

I'll bet someone's feeling very embarrassed this morning. This little present arrived on the RER C line close to Gare d'Austerlitz overnight. It's being called both a beam and just shuttering, so I presume it's been cast but the shuttering has collapsed while the concrete is still soft. Obviously the line will be closed for several days.
(https://pbs.twimg.com/media/EoJjANVWMAE5-FV?format=jpg&name=small)

The track is SNCF Reseau's, and the trains run by SNCF Voyageurs - so at least RATP are not directly involved. The concrete platform is being built to build buildings on, by - of course - Vinci. So somehow, between them, they have to sort out how to extract the thing. I hope they get on with that, rather than arguing about who was at fault or is going to pay - especially as the answer is so obvious. As to the precautions on SNCF's side, and what Vinci were allowed to do and when, no doubt the minister will be demanding another report.

In fact, all trains in and out of Gare d'Austerlitz have been cancelled or are using (mostly) Paris Bercy as a terminus. However, it's not a busy station - and still being rebuilt, I think?

A bridge too far ??

Sounds like the Loddon Bridge, Reading collapse of the A329M in 1972?

The A329M was the rump of a bigger scheme for an M31 (which itself collapsed)

OTC

Both are temporary or falsework (but see below), but that was a much bigger scaffolding structure - which introduces issues of design and build standards you'd hope to avoid with a single span beam like Vinci's one. I just found a presentation on the subject (https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwiFocvz_LTtAhWKgVwKHVTRCVgQFjAQegQIFBAC&url=https%3A%2F%2Fiosh.com%2Fmedia%2F2482%2Fcharlte-hutchison-managing-of-temporary-works-construction-april-2018.pdf&usg=AOvVaw1TdPJpbGsBmlW_0QMLDitJ), full of pictures showing how Loddon Bridge and the resulting inquiry and Bragg report on improving standards haven't stopped it going on.

But further information tells a slightly different story, as does a daylight picture (from l'usine nouvelle (https://www.usinenouvelle.com/article/l-image-du-jour-une-poutre-de-300-tonnes-s-effondre-sur-les-rails-du-rer-c-a-paris.N1035854)):
(https://www.usinenouvelle.com/mediatheque/9/3/3/000921339_image_896x598/poutre-effondree-austerlitz.jpg)

The official description is still both coffrage - formwork - and poutre - beam - but this looks more like a reinforced concrete beam that was being lowered. So I presume it will form a permanent part of the base for a concrete platform to be poured into and onto it later. The simplest explanation is thus that they (Freyssinet, part of Vinci) dropped it with a bump.

I?ve seen the term ?permanent formwork? used in English publications, presumably when something permanent is also used as a frame for casting a slab.

Paul

Yes, that seems to be the most common term - but for two different things, though both are left in place. One is a lightweight liner for foundation trenches, the other spans something, so has to be substantial. In the latter case (and I think in the cracked one) there may be reinforcement for the rest of the beam/deck sticking out of the mould-cum-facing. The French term coffrage perdu has a different literal meaning but also covers both.

Of course this sort of big civil engineering - and bridges in particular - has an enormous scope to go spectacularly wrong. You need to get it all right, from the sums through to swinging huge lumps of surprisingly fragile stuff through the air. I've been embarrassed by getting things wrong, but for most of us it's never so public or on such a scale!

To your last sentence - oh yes! Oops...

Just to wrap this item up - how long did it really take to get that thing out of the way and reopen the line? Answer - 14 days: traffic resumed on the 15th. Of that 10 days were needed to cut the thing up and drag it away, and three days to rebuild the track and OLE etc. Some trains ran on 14th, before full reopening the next day. I think they were aiming for 14th - a Monday - but (and I don't suppose this will surprise anyone) work was affected by a strike for part of the time.
(https://www.usinenouvelle.com/mediatheque/4/9/6/000922694_illustration_large.jpg)
"Credit Freyssinet" it says - probably for the picture, though it could be for that accident!

And six months later, there's another major accident at an SNCF construction site in the Paris region. This time an SNCF staff engineer is missing, presumed killed, in a collapse or landslip. All trains from Montparnasse were halted for several hours, as a precaution, but resumed by late evening.

The site is just north of Massy-Palaiseau, where the RER B and C tracks go over the TGV line from Montparnasse, and the Avenue du Général de Gaulle goes under both in a kind of Three Bridges arrangement. Piling was underway, but what the work is about is not clear, apart from one suggestion that it's another case of making a platform for further buildings over the track. There has been a lot of rain recently, cited as likely to have made the ground (more) unstable. (Report from France Bleu (https://www.francebleu.fr/infos/faits-divers-justice/un-ouvrier-tue-dans-un-eboulement-dans-une-gare-en-essonne-jusqu-a-3-heures-de-retard-pour-le-tgv-1627239252), or in English from TheN24 (https://then24.com/2021/07/25/montparnasse-after-a-fatal-accident-in-massy-%E2%80%8B%E2%80%8Btraffic-very-disrupted/).)

No more news about the accident, and the victim has not yet been located.

I did wonder whether the work was anything to do with Le Grand Paris Express but, while line 18 will pass directly underneath the rail over rail over road bridges, that's a tunneling job. It is in fact the two bridges of the top level, which carry the RER B and C, that are being replaced. This is a major job, as these are two highly skewed twin-track steel lattice girder bridges, and there's very little flat space for putting bridges during a swap. All in all it's a very awkward site, being mostly railway earthworks, and the swap of the spans will take five weeks with both RER lines closed (presumably to build new abutments).

Those two bridge spans even have names, for some reason - pont de Chartres for the RER B, and pont de Gallardon for the RER C one to the north.

It was announced this afternoon that the body of the SNCF engineer killed in last week's accident has now been recovered, after four days of no doubt very difficult work.

I was wondering whether the RER lines, which run on top of the embankments next to the work site, had been interrupted. It turns out that both lines (B&C) were already closed at this point for several weeks, presumably because this phase of site preparation made running the trains unsafe. August is high season for line closures on RATP.