Film-Tech Forum ARCHIVE: Railway tunnel collapse near London.

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Posted by Stephen Furley (Member # 1277) on 06-30-2005, 06:10 PM:

A railway tunnel under construction at Gerrads Cross has collapased.

The line here is in a cutting, and a thin concrete arch had been constructed uver the line to form a tunnel. For several months fill has been added above the concrete arch. The purpose of this work was to allow a supermarket to be built above the railway.

It is reported that twenty metres of the tunnel has collapsed, totally blocking the line. The scale of the collapse really is huge.

Thankfully, it is reported that nobody was hurt.

Posted by Mark Gulbrandsen (Member # 72) on 06-30-2005, 08:06 PM:

A supermarket above the railway.... I wouldn't buy eggs there! Is this the "Smallest Supermarket On Earth"?

Posted by Stephen Furley (Member # 1277) on 07-01-2005, 01:25 AM:

Mark, I don't know how big the building itself will be, but the scale of the construction is massive.

There are some pictures on this site:

web page

There are three links near the top of the page to the pages with the construction pictures.

The concrete arch was only 350mm thick; an impressive structure (when it was standing).

The BBC have a picture of the aftermath of the collapse
here

Note the somewhat under-stated caption to the photograph: "It is thought that tons of rubble is on the railway line". They're not kidding, Trainloads of material for the fill have been coming in since January. They are talking about the line being blocked for three days, but I cannot see how they can possibly do a full inspection of the situation, safely demolish what remains, and remove all the debris from site in that time.

The cause of the collapse is not yet known, so presumably there will have to be a full enquiry before construction is allowed to re-start. I think this could set back the project by years.

Things could have been a lot worse if there had been a crowded commuter train in the tunnel at the time.

Posted by Leo Enticknap (Member # 534) on 07-01-2005, 06:26 AM:

And this comes a week after a trainload of passengers, including my next door neighbour, nearly got baked alive on a broken down Newcastle to London express.

I know that this is probably an irrational reaction which isn't backed up by accident statistics, but they'll be holding an ice hockey championship in Hell before I voluntarily travel by train again - I'm sticking to cars and planes. After her experience last week my neighbour, who had previously criticised my preference for air travel on environmental grounds, will now be joining me on a Leeds/Bradford to Heathrow flight next Thursday.

Posted by Stephen Furley (Member # 1277) on 07-01-2005, 04:10 PM:

The BBC picture didn't really show the scale of what has happend. There are some much better pictures here.

There are many thousands of tons of material that will have to be removed, I think it could take monts to get the trains running, particularly if the rest of the tunnel has to be demolished first, as seems quite likely.

It would have to be on that line; I was planning to use it on Sunday. I don't often travel by train, I used this route a couple of weeks ago, but apart from that, and a couple of trips up to London, the last train journey I made in this Country was probably up to Bradford, in March.

I don't much like to travel by car (I don't drive) and I think flying is about as unpleasant as it gets. I used to travel a lot by rail, but it's just too expensive now, and there are too many restrictions on ticket use. These days, if it's too far to walk I tend to go by bus/coach, or not go at all.

Posted by Leo Enticknap (Member # 534) on 07-01-2005, 04:43 PM:

Yikes! Which begs the question - how many other railway tunnels up and down the country are waiting to cave in like that? OK, this was a newly built one. I guess that the most railway tunnels date from the Industrial Revolution to late Victorian railway boom and therefore are probably not the same issue. But if this collapse was caused by a fundamental flaw in the design of the tunnel, or getting the sums wrong for the weight bearing capacity, for example, I dread to think how many others might be affected.

quote: Stephen Furley
I used to travel a lot by rail, but it's just too expensive now, and there are too many restrictions on ticket use.

Agreed entirely. The reasons I've stopped using trains for any journey which has any other feasible alternative is that (i), it's too expensive, (ii) it is too unreliable, and (iii) the trains themselves are overcrowded, uncomfortable (by which I mean you usually have to stand up for the 2 1/2 hour journey) and full of antisocial yobs.

quote: Stephen Furley
...and I think flying is about as unpleasant as it gets.

But I've found it to be a lot cheaper than rail in most cases (£144 return from York to London if you need to travel before 0930, compared to £60-80 by air - call it £100 after getting to and from airports), certainly one hell of a lot more reliable, and for internal trips the time spent in the air is so short that the unpleasantness isn't a problem. I'd much rather spend 30 minutes in the air than 2 1/2 hours on an overcrowded train with broken down air conditioning. I do accept that lots of short hop flights are not good for the environment. But for work journeys when you've got to rely on being in a certain place at a certain time, I don't think there's any viable alternative at the moment, sadly.

Incidentally, in the fourth picture down on the site linked by Stephen, there are two blobs of light visible in the tunnel, suggesting that two people are in there with torches. Given the likely state of the remaining infrastructure, rather them than me!

Posted by Mark Gulbrandsen (Member # 72) on 07-01-2005, 07:24 PM:

quote: Stephen Furley
Mark, I don't know how big the building itself will be, but the scale of the construction is massive.

I was just making sublime references to "The Smallest Show On Earth". Eggs from a market above the railway........ I wonder if they have to be held in place when the freight trains pass under???

OK, Took a look at the pics and I'd have to say thats just about the stupidest idea I've ever seen being done. Why not just build am I-Beam bridge over the tracks upon which to build the store, thats what they do over the highways and viaducts here. Why on earth do they even need a tunnel? BUT AT LEAST ITS NOT A WAL-MART GOING IN!

I will never ride through that tunnel if I come over there.... the sections don't look very well made nor heavy duty to me like the roof sections of a tunnel should be. They musta been fabricated of composites at the Airbus plant doring a lull time. I do like the VOLVO crane though as it probably has the same high crash standards their cars do.

Mark

Posted by Stephen Furley (Member # 1277) on 07-02-2005, 02:38 PM:

quote: Mark Gulbrandsen
I was just making sublime references to "The Smallest Show On Earth". Eggs from a market above the railway........ I wonder if they have to be held in place when the freight trains pass under???

Ah yes, it sounded sort of familiar, but I couldn't place it. It's a long time since I've seen the film. There are a couple of interesting facts about it at the end of this post.

quote:

OK, Took a look at the pics and I'd have to say thats just about the stupidest idea I've ever seen being done. Why not just build am I-Beam bridge over the tracks upon which to build the store, thats what they do over the highways and viaducts here. Why on earth do they even need a tunnel? BUT AT LEAST ITS NOT A WAL-MART GOING IN!

This is from the web site of Extrado, the company responsible for the tunnel:

quote:
The intent is to construct the tunnel over the railway lines during nighttime occupations, and to backfill the structure up to 4m over the crown of the arch. The store development itself will be situated over the arch and will be supported by it. The structure itself is one of he largest TechSpan arches, with a span of 20m, a rise of 7.15m and a total length of 305m.

The web site has been taken down at the moment.

Look at those figures; the tunnel is 305metres long, and spans 20 metres. The cutting has sloping sides, so the width at the top which a bridge would have to span would be much greater, maybe 30 metres. Therefore such a bridge as you propose would be 30 metres long, which could probably be done as a single span, but it would have to be 305 metres wide. That would be quite some bridge!

The other reason is the area where it is situated; Gerrard's Cross is a rather 'posh' area, with some of the highest property values in the uk. Tesco has traditionally been seen as a rather down-market store, though it has moved up in the world somewhat in recent years. There was intense opposition in the area to the building of the store, even built as it will be over the tunnel, and presumably with much landscaping. I think any attempt to build it on top of a massive steel girder bridge would probably have led to the developers being lynched!

quote: Mark Gulbrandsen

I will never ride through that tunnel if I come over there.... the sections don't look very well made nor heavy duty to me like the roof sections of a tunnel should be. They musta been fabricated of composites at the Airbus plant doring a lull time. I do like the VOLVO crane though as it probably has the same high crash standards their cars do.

The cause of the failure has not yet been made public, though something whigh I read this morning written by an engineer involved suggests that the cause is now known.

There are indications however that there is no basic design fault with the tunnel (a similar one was recently constructed to carry a road as part of the Heathrow Airport terminal 5 project, and others exist) but that the problem lay somewhere in the construction. We will have to wait for the report.

The arch really is an incredible bit of engineering, those concrete segments are only 350mm thick. Sadly the whole thing will be buried underground when it's finished, so it wont be possible to see it. I will be quite happy to ride through it again once the problems are sorted out.

Two things about "The Smallest Show On Earth". The projection box at MOMI, now NFT3, had a large window in its back wall, as it was, in effect, an exhibit in the museum. There was a still from the film displayed in this window. The ancient, and supposed to look that way, front shutter Kalee projectors in the film would have been about 30-35 years old when the film was made. At that time MOMI was equipped with DP-70s (since replaced by Vic 8s) which were built in 1958, and were therefore 41 years old when MOMI closed; considerably older than the ones in the film were when it was made.

The big cinema in the film was filmed in two genuine cinemas in London, The exterior was the Gaumont Palace, later Odeon and now Apollo, Hammersmith and the interior was the Odeon Richmond, but the 'Bijou Kinema' used sets, The interior was built in the studio, but the exterior, as you remember, was by a railway. The set for this was built between two real railway bridges at Kilburn in North West London. You pass over one of these bridges when travelling to Gerrard's Cross where this accident was; it's about 12 miles away.

As you pass through Kilburn on the train you can see a square tower with the word 'State' in neon on it. This is now a bingo hall, but was previously the 'Gaumont State Kilburn', Britain's largest purpose-built cinema, at 4004 seats. Anything over 3000 here was unusual.

Posted by Ben Wales (Member # 92) on 07-02-2005, 05:01 PM:

I belive it is the new site for Tesco and the Local people do not want built there in the first place.

What's that Tesco moto "You Shop, We Drop (Tons of Rubble on you)

Posted by Leo Enticknap (Member # 534) on 07-03-2005, 03:50 PM:

quote:
BUT AT LEAST ITS NOT A WAL-MART GOING IN!

It could easily have been - one of Tesco's rival supermarket chains, Asda, was bought up by Wal-Mart a couple of years ago.