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M.Mouse
18th Jul 2011, 20:42
Spectacular mast collapse. (http://nos.nl/video/256514-zendmast-hoogersmilde-stort-in.html)

sitigeltfel
18th Jul 2011, 20:48
I believe a fire broke out in the structure that weakened it and caused it to collapse.

west lakes
18th Jul 2011, 20:49
Brief but it might help

DutchNews.nl - Transmitter fires disrupt radio and tv broadcasts (http://www.dutchnews.nl/news/archives/2011/07/transmitter_fires_disrupt_radi.php)

Jhieminga
18th Jul 2011, 20:49
Fire broke out in the mast during works there. Fire service responded but decided to clear the surrounding area as the location in the mast made extinguishing difficult. Weakened by the fire, the mast then collapsed.

Strangely enough a small fire also broke out in a second (similar) mast in IJsselstein on the same afternoon. This was quickly extinguished but the transmitter was shut down as a precaution.

Radio service in North and Central The Netherlands has now been resumed ;)

Edited to add: According to a colleague who lives near there it looks a bit like a war zone there. On the other hand, the MSA for the South-East sector of EHGG can now be adjusted downwards...:}

G-CPTN
18th Jul 2011, 21:05
We have GoogleTranslate (http://translate.google.com/) for text and can search GoogleImages (http://www.google.co.uk/imghp) by dragging and dropping an image - how long before we can expect GoogleTranslateImages (http://mashable.com/2010/02/17/google-goggles-translation/) to accept videos being dragged and dropped for translation of the commentary?
http://www.qtl.co.il/img/trans.png

G&T ice n slice
18th Jul 2011, 21:53
"Co-incidence" two masts having fires...

Didn't anyone notice the secret black helicopters???

Sallyann1234
18th Jul 2011, 22:18
Not a co-incidence. I understand there were "maintenance issues" with similar equipment in the two towers. Also understand careers were abruptly shortened.

ChristiaanJ
18th Jul 2011, 22:20
Westlakes' link pretty well covers it.
If anybody wants more info, I can listen to it again.
The fire at Lopik (the original Dutch TV transmitter station, and a major radio transmitter station for a very long time) indeed seems to have been pure coincidence.

CJ

Lon More
18th Jul 2011, 22:27
There's at least one more mast in the South of the country near Roermond. There are a number of checks being catrried out on that.

The area around the mast near Hoogersmilde is considered too dangerous for the engineers to enter at the moment.

An emergency repeater antenna is to be erected near Gronigen in the next few days. Presently surveying the site to ensure the cable anchors etc. can be securely placed.

aviation link LOPIK is a point on a number of SIDs from EHAM

tony draper
18th Jul 2011, 22:46
I suppose one of the advantages of being such a flat country you dont need very tall transmitter masts.
:)

G-CPTN
18th Jul 2011, 22:50
Yea, but you can't build them on the top of hills . . .

tony draper
18th Jul 2011, 22:56
Had not read the text when I posted that, apparently it were a 300 metre jobby ,didn't look that tall as it was falling down in that clip,:

603DX
19th Jul 2011, 10:03
In the highly specialised field of very tall telecom structures, it is rare indeed to have video of their collapse. We have had a few fail in the UK, but as far as I know none of them were filmed.

The 1,265 ft (386m) Emley Moor TV mast in Yorkshire collapsed in 1969, due to a combination of heavy asymmetric ice accumulations on its steel support guys, with simultaneous transverse oscillations of its tubular steel shaft due to vortex excitation in steady wind conditions. Many folk lost their TV pictures that icy night, and "lessons were learned" about the critical design conditions for masts of that type and extreme height.

This Hoogersmilde collapse seems to have been triggered by the effects of intense heat from the fire causing severe loss of strength in the base region of the upper steel mast section. Although vastly different types of structure, a similar weakening effect from heating of the steel structure caused the twin towers to suffer progressive collapse on 9/11.

tony draper
19th Jul 2011, 10:07
Always fancied getting to the top of Emley Moor,put some CCTV cameras on a repeater mast not far away,nowhere near as high though,(some buggah kept nicking the cameras from the sub station so these camers were to watch the other cameras)
:uhoh:

Senior Pilot
19th Jul 2011, 10:29
Maybe a bit easier to watch:

‪NOS Nieuws - Zendmast Hoogersmilde stort in + nabeschouwing 15 7 2011‬‏ - YouTube

Sallyann1234
19th Jul 2011, 11:22
Always fancied getting to the top of Emley Moor,put some CCTV cameras on a repeater mast not far away,nowhere near as high though,(some buggah kept nicking the cameras from the sub station so these camers were to watch the other cameras)

Been there, done that. The view from the observation gallery is great, but the ride up the rickety internal lift is a bit alarming - a sort of rack and pinion setup and very noisy. Looking down from the gallery you can still see the marks on the ground where the original mast fell.

Sallyann1234
19th Jul 2011, 11:37
This Hoogersmilde collapse seems to have been triggered by the effects of intense heat from the fire causing severe loss of strength in the base region of the upper steel mast section. Although vastly different types of structure, a similar weakening effect from heating of the steel structure caused the twin towers to suffer progressive collapse on 9/11.

The problem with guyed masts is that the total downward force exerted by the guys is immense, and the centre of gravity of their combined vertical thrust must always be inside the area of the mast at every point. The mast itself is relatively weak, and any off-centre distortion e.g. due to heat will cause the guys to actually pull it down. You can see that happening in the video where the guys are pulling the top section down past the lower section.

DX Wombat
19th Jul 2011, 12:08
Here you are, Emley Moor Transmitter Collapse (http://tx.mb21.co.uk/emley/eyewitness/index.shtml) When I moved here in 1974 many people still had their tvs tuned to the Newcastle Region transmitters even though the new transmitter at Emley Moor was up and running. The mast can be seen for miles and miles both night and day.

603DX
19th Jul 2011, 12:56
The problem with guyed masts is that the total downward force exerted by the guys is immense, and the centre of gravity of their combined vertical thrust must always be inside the area of the mast at every point.

Not quite, Sallyann1234, many masts have their guy thrust resultant outside the mast area under high wind load conditions, in the upper regions. This causes tensions to develop at the bolted joints between mast sections, which they have to be designed to resist.

However, I have now viewed this video several times, and have revised my view of the cause. I think there was a fire located inside the thin-walled tubular steel section of the mast column, between guy attachment levels. The burning material might possibly have been the foamed plastic filling inside antenna waveguides, though this is a guess. Certainly, there was thick black smoke emerging near the mast top like a chimney, which burning plastics do produce, but I have no idea what might have ignited the burning material.

I suspect that the intense internal heat buckled the tube walls locally like a crumpled Coke can, and the accumulated guy pretensions did the rest. Clicking the video to freeze the action, a flaming end of the tube can be clearly seen falling to the right behind the trees, possibly indicating the precise location of the fire. Unfortunately, there is no "AAIB report" system in the world of telecom structures, so the details of how this occurred may never be made public - things are often played close to the chest, for various reasons including insurance, possible litigation, and so on.

G-CPTN
19th Jul 2011, 14:43
I thought I detected the words "air conditioning" (in English) among the Dutch of the original commentary (at 1:20) and "cooling" (at 1:27).
There would be no need for air-conditioning of the antenna, of course, but it is reasonable to assume that equipment for ventilation of the accommodation below the actual antenna would be located on the top of that accommodation - at the base of the antenna.

An electrical fault (speculation here) could cause a fire which could spread to combustible material nearby.

vaqueroaero
19th Jul 2011, 15:12
Maybe slightly off topic and it may have been posted before, but check this out.

‪Stairway to Heaven‬‏ - YouTube

Personally, you couldn't pay me enough to do this!

Davaar
19th Jul 2011, 15:24
M Mouse: my only Dutch is:

"Echt!!!!", or "Echt????", or "Echt????!!!!".

with the occasional "Gott Verdikkime" (I think it is).

It is an expressive language.

Is more really required?

ChristiaanJ
19th Jul 2011, 16:20
I thought I detected the words "air conditioning" (in English) among the Dutch of the original commentary (at 1:20) and "cooling" (at 1:27).
The chap being interviewed was working on the air conditioning on the top floor of the concrete part of the tower. Colleagues, who just had come back from lunch, and who were pulling cables into the upper part of the tower (the 'tube' and latticework) discovered the fire, which was much higher (at 180m), about on the transition between 'tube' and laticework.
So no obvious link between the air conditioning and the fire.

CJ

PS A small detail.... when I was a teenager, we lived in Leeuwarden, and we got our TV from Smilde. I didn't know the mast was that high, though. Such tall masts for TV and FM (VHF) are common in the Netherlands, because it's so flat.....

Sallyann1234
19th Jul 2011, 16:39
However, I have now viewed this video several times, and have revised my view of the cause. I think there was a fire located inside the thin-walled tubular steel section of the mast column, between guy attachment levels. The burning material might possibly have been the foamed plastic filling inside antenna waveguides, though this is a guess.
They won't be waveguides at the frequencies involved, and they won't be filled with foam. They will be very large diameter coaxial feeders with relatively small plastic spacers to hold the inner conductor in place. It is usual to pressurise the feeder slightly with nitrogen to keep out damp air.
If you look at the video where the lower section falls to the right, you can see the coaxial feeders holding the lower tower section back to the concrete structure.

tony draper
19th Jul 2011, 17:38
Those masts generally have clusters of microwave dishes at lower levels, that might explain wave guides.
:)

ChristiaanJ
19th Jul 2011, 18:03
Those masts generally have clusters of microwave dishes at lower levels, that might explain wave guides.
:)TD....
Microwave dishes would be in the 'head' of the concrete 'nail' (for stability reasons), not much further up.
Looking at the video, I would say we are looking at a cellphone aerial cluster at the level where the fire was, with the associated electronics inside the top of the 'tube'.
The actual TV and FM radio aerials are right at the top of the tower (the bit that came off first).

Nice one.... classic JetBlast thread with wild guesses coming in left right and centre.

CJ

Sallyann1234
19th Jul 2011, 18:34
ChristiaanJ - it is/was not a cellphone aerial, it was an omnidirectional VHF array, probably broadcasting.

see here:
Vrijdag 15 juli 2011: Zendmast Hoogersmilde stort in na brand (http://www.kilroynews.net/special/2011-07/20110715.htm)

603DX
19th Jul 2011, 18:36
Nice one.... classic JetBlast thread with wild guesses coming in left right and centre

Agreed, Christiaan, and all the better because for once no one was even injured, let alone killed in the accident! My own sloppy guess about "foam-filled waveguides" simply added to the confusion, and Sallyann1234 quite rightly picked me up on it. I should have known better, though to be brutally honest when I was working on the analysis of guyed mast structures, the feeders were a damned nuisance because all that interests the engineer for structural loadings is the size, shape, position and mass per metre of feeders. Their electrical classifications are of no interest whatever, and are irrelevant to the dynamic and quasi-static wind and dead loading calculations, but their large number and fiddly nature makes the task a little tedious.

11Fan
19th Jul 2011, 18:37
If you watch the video closely, you can see puffs of white smoke coming out from where the mast breaks, right before it actually collapses.

And previously mentioned, are we to believe that those black helicopters were just there by chance?

Just how close do you have to be to set off remote detonation?

We should be told.


Me, personally, I think it were aliens.

What, time for my meds again?

herman the crab
19th Jul 2011, 21:08
I thought the helicopters were all over the 405 here this weekend while they removed the alien's secret entrance to their bunkers?

Notice how they distracted everyone with the 3.5 hr car chase? ;)

HTC

11Fan
19th Jul 2011, 21:15
.....removed the alien's secret entrance to their bunkers?

Word is they moved it up to Old Fort Tejon. That's what all the digging was about.

Notice how they distracted everyone with the 3.5 hr car chase?

And they couldn't go any further up the "grapevine" because it was too dark.

Sure. :rolleyes:

herman the crab
19th Jul 2011, 21:23
:) yeah I gave up after about midnight as they stopped broadcasting so that they had some new news for the morning show!

I haven't been up that way for a long time after dark but I seem to remember it does get pretty dark up there at night and I suppose without ground reference and non IFR I wouldn't be too keen to keep going either.

Hell - Whiteman was back enough during daylight hours last week!

HTC

ChristiaanJ
19th Jul 2011, 23:01
ChristiaanJ - it is/was not a cellphone aerial, it was an omnidirectional VHF array, probably broadcasting.
see here:
Vrijdag 15 juli 2011: Zendmast Hoogersmilde stort in na brand (http://www.kilroynews.net/special/2011-07/20110715.htm)
SallyAnn,
Looked again, and I agree, and almost certainly broadcasting, since Dutch news had a lot of waffle about how many radio (VHF FM) programs had been interrupted, apart from the TV.

Thanks for the link to that set of photos!
And BTW, towards the end of the set there are a couple of photos which do look like cellphone aerials, but I agree totally with you, that the 'higher-up' arrays were not cellphone!

CJ

Lon More
20th Jul 2011, 00:15
Lopik is also a Tx/Rx for ATC from Schiphol and Maastricht UAC. IIRC the arrays would be pretty high

radeng
20th Jul 2011, 08:42
A lot of microwave links now have the actual transceiver right up at the dish.

603DX
20th Jul 2011, 12:33
The helicopter seen in the collapse video reminded me of three potential mast collapses which have occurred in the UK due to aircraft striking a steel guy rope.

The Caradon Hill TV mast in Cornwall was hit by a low flying RAF Hunter, which crashed after the pilot ejected safely. The guy rope was damaged, so it was replaced. The Hunter was not repairable ...

The Caldbeck TV mast in Cumbria was hit by a USAF Phantom, severing the outer wing section and severely damaging the guy. The aircraft did a complete roll, then limped back to its base rather the worse for wear. The fallen wing panel was later reclaimed by the Americans, and the guy rope was replaced.

The Dover TV mast in Kent was struck by a small French private aircraft, which sadly crashed, killing the occupants. The guy rope was undamaged.

If any of the guys had been severed completely, there was a possibility that the mast would have "self-destructed" and collapsed, due to the considerable unbalanced pre-tensions in the other two, pulling the slender mast column well off-centre.

Lon More
20th Jul 2011, 14:41
IIRC a Belgian Air Force Mirage (?) flew into the guy wires of the Radio Luxembourg transmitter mast back in the 1970s. Often low viz. down there in the Ardennes.Couldn't find anyting with GooGoo (should try in French)

Edited to add, found it31 Juillet 1981 : Un avion militaire belge percute l'émetteur de Dudelange.

L'accident provoque la mort du pilote et de deux techniciens qui travaillait dans le bâtiment au pied du pylône.

L'émetteur est totalement détruit. Conséquence: RTL Télévision est dans l'impossibilité d'émettre pendant plusieurs heures, jusqu'à la mise en place d'un système de secours (moins performant).

Le Mirage 5 N° BR 16 qui est entré en collision avec le pylône TV de RTL était piloté par Bob Gennart, commandant de la base de Florennes.

A Belgian military aircraft struck the transmitter at Dudelange.
The accident caused the death of the pilot and of two technicians who were working in the building at the foot of the mast.
The transmitter is totally destroyed. As a result RTL television could not broadcast for several hours until a lower power emergency system was installed.
The Mirage 5, BR16, involved in the collision with the mast, was flown by Bob Gennart, CO of the Florennes Airbase.

radeng
20th Jul 2011, 15:00
I would expect it not to be a career enhancing incident....

Storminnorm
20th Jul 2011, 15:06
I think someone was SMOKING up there!!!