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Wrong side failure of a set of boom barriers in Utah

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Wrong side failure of a set of boom barriers in Utah

Unread postby Andrew Waugh » Wed Jan 25, 2017 5:50 am

https://www.theguardian.com/global/video/2017/jan/25/passenger-train-in-utah-slams-into-truck-at-high-speed-video

Commuter train in Utah smashes into a FedEx B-double truck - the boom barriers weren't active.

Massive amount of luck for all concerned. The train smashed through the first truck trailer, so the truck driver wasn't seriously injured. FedEx trucks don't contain heavy objects, so the train crew and passengers weren't seriously injured. And a second FedEx truck had just cleared the crossing.

It appears the car with the dash cam was a police car, and it would appear that they were on the ball as they stopped at the level crossing even though the boom barriers weren't working.

Note that at the end, the booms activate (wreckage on the line?). But no-one clears the line - I'd be worried by a train coming the other way.
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Re: Wrong side failure of a set of boom barriers in Utah

Unread postby Mike Hodgson » Wed Jan 25, 2017 8:38 pm

I think I am more concerned that the wig-wags weren't on than by the barriers being up, although I suppose it makes little difference. If the police had stopped before the accident without crossing have struck in, that suggests they saw or heard the approaching train. Perhaps visibility was not as good from the truck coming from the other side of the road .
Perhaps I am over-cautious but when approaching an AHB even though the lights aren't flashing , I nevertheless look to see if there are any trains about, in so far as is practicable. But one could not reasonably accuse the truck driver of negligence

The caption to the video blames the failure to activate on the weather, and seemingly implies the barriers were frozen in the raised position, along the lines of Abbots Ripton. That could hardly be the case in view of your comment about the activation after the accident. However I assume there will be an official investigation, and I don't wish to speculate but I suppose this could well find the the weather in some way caused or at least contributed to the equipment's failure fail to detect the approaching train and initiate the crossing cycle.

As to the cause of the post-collision activation, although debris could be one possible explanation I would be more inclined to suspect the strike -out track circuit or treadle being interpreted as the train approaching in the opposite direction, ie as a strike-in
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Re: Wrong side failure of a set of boom barriers in Utah

Unread postby Andrew Waugh » Wed Jan 25, 2017 9:58 pm

A couple of comments from a place with a lot of AHBs.

Yes, the truck driver would have had far worse visibility of the approaching train than the police. The road crosses the railway at an angle. The train was approaching the crossing on the non-driver side of the truck. It is well recognised in Australia (and in the US, presumably) that drivers of large prime movers have extremely poor vision out the off-side windows, especially at acute angle crossings. This is because the side windows are small, are set quite forward, the cab is wide, and the driver seated at the extreme far side. It's a serious accident risk in Australia, where the majority of the level crossings are completely unprotected.

In any case, of course, the driver is not expected to look out for trains at a crossing with AHBs. In Australia (and the US) AHBs are only fitted at high risk crossings - risk being calculated based on the visibility of approaching trains, and the amount of traffic. So you would be unlikely to see the approaching train, even if you looked.

The triggering of the protection equipment at the end of the video is significant. It shows that the flashing lights were not active before (i.e. their lack is not an artifact of the video), which means that the boom barriers were not frozen in the vertical position. It also shows that the control equipment was operational. The level crossing had not been activated by the approaching train.

The comment from the Utah Transit Authority spokesman (sic!) is astonishing. Cold and ice is the likely immediate cause of the problem, certainly. But cold and ice are not uncommon in the US; they shouldn't cause any problems with track circuit activation of level crossings. AHBs would be useless as safety devices if they even occasionally failed due to ice. There is an underlying reason why the track circuit failed, beyond the problems of cold and ice.

Yes, good point about the train stopping on the other approach track circuit (no treadles on main line US railroads), triggering the protection equipment after a timeout.
Last edited by Andrew Waugh on Wed Jan 25, 2017 11:18 pm, edited 1 time in total.
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Re: Wrong side failure of a set of boom barriers in Utah

Unread postby JRB » Wed Jan 25, 2017 10:36 pm

Treadles not possible in USA under the "Not invented here" convention.
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Re: Wrong side failure of a set of boom barriers in Utah

Unread postby scarpa » Thu Jan 26, 2017 8:25 am

A single strike In treadle would prevented this incident.They don t seem to have the variety of different track circuits we have for different purposes.HVI tracks would have been reliable to operate the barrier strike in and a treadle.
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Re: Wrong side failure of a set of boom barriers in Utah

Unread postby Mike Hodgson » Thu Jan 26, 2017 11:02 am

scarpa wrote:A single strike In treadle would prevented this incident.They don t seem to have the variety of different track circuits we have for different purposes.HVI tracks would have been reliable to operate the barrier strike in and a treadle.


As I said, I don't want to speculate, but another possibility is that the strike-in circuitry did work (detect the train approaching), but the activation part of the circuitry somehow failed to operate - perhaps a relay failure or poor design. There could have been enough vibration from the impact to clear a fault such as a dirty contact as a dirty contact or a relay sticking. I hope we get to hear what the investigation finds. I don't see it as possible to make these things 100% fail safe.
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Re: Wrong side failure of a set of boom barriers in Utah

Unread postby Andrew Waugh » Thu Jan 26, 2017 12:00 pm

You are making an assumption about what caused the accident.

I would point out, again, that the US has a very, very, large number of AHBs. Many of these are in locations that routinely experience significant falls of snow, and very low temperatures. But the US does not have a problem with wrong side failures of AHBs. This suggests that, even if the immediate cause of the accident was the failure of a track circuit to detect the train, there must be something unusual going on at this level crossing.

With regard to treadles. In the UK, treadles are provided "at the running-on end [of the level crossing approach track circuit] to guard against the maloperation of the track circuit by lightweight vehicles" (Railway Control Systems, IRSE, p140). Lightweight rail vehicles, as used in the UK, are almost unknown on heavy rail lines in the US, and so this is not a problem that needs to be controlled. It's worth noting that the train in this incident consists of three large double deck passenger cars, a single deck car, and a four axle locomotive. Such a train is most unlikely to have problems in shunting a track circuit, except under very abnormal circumstances.

Finally, a simple failure to shunt a track circuit is not the only cause of this type of accident. Consider this almost identical accident in Kalgoorlie, Australia, in 2007 (https://www.atsb.gov.au/media/24308/rair2007002_001.pdf). In this accident, the cause was circuit alterations in a nearby relay room. Carrying out these alterations caused operation of a level crossing. As a flagman was not available, the technician and commissioning engineer installed a strap to prevent operation of the level crossing (while not excusing this approach, they were working in a time window granted to them by the controlling signaller during which no trains would pass through). Unfortunately, when they fixed the problem they forgot to remove the temporary strap.
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Re: Wrong side failure of a set of boom barriers in Utah

Unread postby Mike Hodgson » Thu Jan 26, 2017 12:49 pm

Andrew Waugh wrote:You are making an assumption about what caused the accident.


I am not making any assumptions as to what caused it. All I am saying is that there are a number of possibilities.
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Re: Wrong side failure of a set of boom barriers in Utah

Unread postby Signal-sighter » Thu Jan 26, 2017 9:37 pm

Referring to this crossing as an 'AHB' is in my view as erroneous as trying to infer a cause by watching the video. It is not an AHB as we would understand the term in the UK or, I expect, Australia. It has road lights and barriers but using the acronym AHB predicates all sorts of ideas about how we expect it should operate and how it should fail. I know nothing of how American grade crossings work but I'd guess the principles and circuitry have very little in common with UK signalling practice.
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Re: Wrong side failure of a set of boom barriers in Utah

Unread postby Andrew Waugh » Thu Jan 26, 2017 10:41 pm

Mike Hodgson wrote:
Andrew Waugh wrote:You are making an assumption about what caused the accident.


I am not making any assumptions as to what caused it. All I am saying is that there are a number of possibilities.


Sorry, Mike. I was referring to Scarpa's post, not yours. You posted between when I started my reply and when I posted it...
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Re: Wrong side failure of a set of boom barriers in Utah

Unread postby Mike Hodgson » Thu Jan 26, 2017 10:59 pm

Signal-sighter wrote:Referring to this crossing as an 'AHB' is in my view as erroneous as trying to infer a cause by watching the video. It is not an AHB as we would understand the term in the UK or, I expect, Australia.


Fair comment - I don't know what the correct American terminology is.
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Re: Wrong side failure of a set of boom barriers in Utah

Unread postby S&TEngineer » Fri Jan 27, 2017 8:24 am

Mike Hodgson wrote:
Signal-sighter wrote:Referring to this crossing as an 'AHB' is in my view as erroneous as trying to infer a cause by watching the video. It is not an AHB as we would understand the term in the UK or, I expect, Australia.


Fair comment - I don't know what the correct American terminology is.


Information can be found here: http://safety.fhwa.dot.gov/xings/com_ro ... /index.htm and in particular this section of the document which describes alternative control systems: http://safety.fhwa.dot.gov/xings/com_ro ... c04b.htm#i

Figures 41 to 49 in the latter document show the different types of 'strike in' controls.
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Re: Wrong side failure of a set of boom barriers in Utah

Unread postby scarpa » Fri Jan 27, 2017 11:18 pm

Veering off the subject the introduction of treadles was brought about by a wrongside failure in East Anglia to a A.H.B. crossing where the crossing failed to operate due to a mini whirlwind causing the fine fen soil covering the rails insulating them . These whirlwinds still happen .
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Re: Wrong side failure of a set of boom barriers in Utah

Unread postby StevieG » Sat Jan 28, 2017 10:11 pm

scarpa wrote:Veering off the subject the introduction of treadles was brought about by a wrongside failure in East Anglia to a A.H.B. crossing where the crossing failed to operate due to a mini whirlwind causing the fine fen soil covering the rails insulating them . These whirlwinds still happen .
For some years I worked with rail people who worked, and/or lived in/around, the Peterborough area, and I also lived in Werrington for two years : -
- There is (or was?) a fen-related loose, dry soil phenomenon, caused not necessarily by 'whirlwind' but by strong (in this area, NE-E-SE) winds which I understood was called a 'fen blow'.
I once experienced this whilst on a train between Holme and Yaxley, and it was like a brown fog with visibility up to about 100 yards only, but with particles of soil very audibly hitting the carriage windows.
IMHO it seems unlikely that a constant or reducing 'straight' wind would deposit sufficient soil on rails for an adverse effect on train detection, but I couldn't say whether a 'whirlwind' moving on quickly might do so.

[ Hopefully, end of tangential 'veer' off-topic. (?)]
BZOH

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Re: Wrong side failure of a set of boom barriers in Utah

Unread postby Wilkinstown » Sun Jan 29, 2017 10:02 am

Was there a station stop nearby ? Is it possible that the crossing is not track circuit initiated ? Could the train have over-run a normal station stop for one reason or another ? Might there be signal interlocking associated with this crossing ?
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