Re: [SystemSafety] Lac-Megantic disaster

From: Eliop < >
Date: Thu, 11 Jul 2013 18:48:54 +0200


In other words, the braking control circuit is fail-safe, but the braking power circuit is not...

Curious.

2013/7/11 <peter.sheppard_at_xxxxxx

>
> Railway wagons normally have two brake lines, main line and train line.
> Each wagon has a local reservoir and brakes are applied through a triple
> valve and work through a difference in pressure between the main line and
> the train line. (Pressure from the local reservoir is fed through the
> triple valve to the brake cylinders). So the essential issue is that the
> reservoir needs pressure in it for the brakes to be applied.
>
> All brake systems leak, so you need an engine attached to maintain the air
> pressure (or vacuum) - it makes no difference on the system in use.
>
> If that engine stops (which apparently it did) the air leaks off and
> whilst the brakes will initially be applied, they will eventually leak off
> as all the pressure dissipates.
>
> That is why all wagons either have handbrakes or spring applied parking
> brakes.
>
> It appears (from what I have read) that one locomotive was left running,
> but that was shut down when the fire brigade attended. Locomotive hand
> brakes were applied, but they are designed to hold a locomotive, not a 70
> wagon train on a 1.2% gradient and it rolled!
>
> Regards
>
> Peter
>
> Peter Sheppard
> Senior Safety Engineer and Validator
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> *Rolf Spiker <rolf.spiker_at_xxxxxx > Sent by: systemsafety-bounces_at_xxxxxx > 11/07/2013 17:11
> To
> Matt Squair <mattsquair_at_xxxxxx > systemsafety_at_xxxxxx > cc
> Subject
> Re: [SystemSafety] Lac-Megantic disaster
>
>
>
>
>
> Hi Matt,
>
> Your answer is a little puzzling to me
>
> Your first two paragraphs:
> Train brakes rely on pressure in what's called the brake pipe to keep them
> 'off'. When brake pipe pressure falls below a set value the brakes engage.
> This is the Westinghouse system of air brakes basically.
>
> That gives you a fail safe train brake that will actuate in the event that
> the train inadvertently parts, in freight operations a not insignificant
> risk due to excessive inter-train dynamic forces.
>
> Are clearly my mentioned : With no any power (in this case vacuum), all
> brakes are fully engaged.
>
> The following paragraphs are discussing the opposite I think
> You need power to get the brakes engaged.
> Is that right?
>
> *Regards*
> * **Rolf Spiker**
> Rolf Spiker of Exida.com*
> Senior Safety Consultant & Partner
> Phone : +31 (0)318 414 505
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> *From:* Matt Squair [mailto:mattsquair_at_xxxxxx > Sent:* Thursday, July 11, 2013 11:48 AM*
> To:* Rolf Spiker; Bielefield Safety List*
> Subject:* Re: [SystemSafety] Lac-Megantic disaster
>
> Train brakes rely on pressure in what's called the brake pipe to keep them
> 'off'. When brake pipe pressure falls below a set value the brakes engage.
> This is the Westinghouse system of air brakes basically.
>
> That gives you a fail safe train brake that will actuate in the event that
> the train inadvertently parts, in freight operations a not insignificant
> risk due to excessive inter-train dynamic forces.
>
> However the brake actuation force is also normally provided by a pneumatic
> reservoir on each car, these are kept topped up by what's called the main
> reservoir pipe. Which is pressurized from air reservoirs located on the
> locomotives in the train, which are in turn pressurized by locomotive air
> compressors.
>
> Like all pneumatic systems there's a certain amount of leakage, so, if the
> locomotive doesn't keep the main reservoir topped up with its air
> compressor the pressure will slowly bleed off and the train brake will
> disengage.
>
> Which is kind of why mechanical spring style park brakes are always used
> to park, and why the comments in the media that the loco was running to
> keep the brakes on is misleading.
>
> The actual reason has to do with operational efficiency as it takes time
> to pump up a trains reservoirs from ambient. Leave one loco on to run its
> air compressor and you can get away quickly in the morning.
>
> Of course if all the needed park brakes aren't applied and then for some
> reason the online loco is shutdown...
>
> As a side note, an increasing number of locomotives have what's called an
> Auto Engine Start Stop function to save fuel. With AESS the locomotives
> control system will monitor air reservoir pressure and only start the main
> engine if needed to run the air compressor. Modern freight trains are quite
> sophisticated and complicated systems.
>
> So one should be careful of believing what's being said about the 'cause'
> of the shutdown, just yet.
>
> Hope that helps. :)
> --
> Matt Squair
> Sent with *Sparrow* <http://www.sparrowmailapp.com/?sig>
>
>
> On Thursday, 11 July 2013 at 7:09 PM, Rolf Spiker wrote:
> I always thought that the brakes of a train (also for trucks) have to be
> energized to makes them free.
> (Vacuum driven energizing)
> c
>
> *Regards*
> * **Rolf Spiker**
> Rolf Spiker of Exida.com*
> Senior Safety Consultant & Partner
> Phone : +31 (0)318 414 505
> Mobile: +31 (0)6 116 225 52
> E Mail: *rolf.spiker_at_xxxxxx > Mail address:
> Exida.com
> Att: R.Th.E. Spiker
> Nassaulaan 41
> 6721DX Bennekom
> The Netherlands
>
> Established Company address:
> 64 N. Main Street
> Sellersville, PA 18960
> USA
> <image005.jpg>
> To view our Equipment database with certified elements go to: *
> www.sael-online.com* <http://www.sael-online.com/>
> <image006.png>
>
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> *From:* *systemsafety-bounces_at_xxxxxx > *mailto:systemsafety-bounces_at_xxxxxx > *On Behalf Of *Peter Bernard Ladkin*
> Sent:* Thursday, July 11, 2013 7:17 AM*
> To:* Matthew Squair*
> Cc:* Bielefield Safety List*
> Subject:* Re: [SystemSafety] Lac-Megantic disaster
>
> There are a lot of questions. The BBC is saying that the locomotive was
> left running as the train was parked 7 miles up the line, to power braking
> systems; that fire services powered down the locomotive in the course of
> extinguishing a small fire; that the train started moving downhill shortly
> after that:
>
> [begin BBC quote]
>
>
>
> The train, carrying 72 cars of crude oil, was parked shortly before
> midnight on Friday in the town of Nantes about seven miles (11km) away.
>
> Local firefighters were later called to put out a fire on the train.
>
> While tackling that blaze, they shut down a locomotive that had apparently
> been left running to keep the brakes engaged.
>
> Shortly afterwards the train began moving downhill in an 18-minute
> journey, gathering speed until it derailed in Lac-Megantic and exploded.
> [end BBC quote]
>
>
> Questions.
> 1 (HaroldThimbleby) Powered braking systems on freight are often
> air-powered. But they are fail-safe - losing power means they engage. So
> what system here requires power to remain engaged?
> 2. Fire services called to a plant usually have an operator's emergency
> number to contact about plant details, and the operation of unattended
> running equipment. Is there no such system for freight trains? Why not?
>
> 3. That an engine attached to a train with HazMat on board could be left
> running and unattended. 4. How the railroad company could tell at this
> stage whether and how many handbrakes were or were not applied.
>
> BTW, this is another accident situation predicted explicitly by
> sociologists Perrow and Clarke ( The Next Catastrophe, Princeton U.P.,
> 2007, resp. Worst Cases, U. Chicago Press 2005), as with flooding Mark 1
> BWRs. But they were more concerned with Hazmats such as chlorine and
> hydrogen fluoride than oil.
>
> It should give engineers pause that sociologists are better at identifying
> hazards than they are. (Except for computer networks, of course, where I
> think Bellovin's 1992 paper on possible TCP/IP exploits takes some beating
> for prediction.)
>
> PBL
>
> Prof. Peter Bernard Ladkin, University of Bielefeld and Causalis Limited
>
> On 11 Jul 2013, at 00:26, Harold Thimbleby ....... wrote:
>
> <a comment about air brakes>
>
> .... BBC News iPad App .......
>
> Engineer blamed for Canada blast
>
> A rail operator's chief executive blames a local engineer for a runaway
> train that derailed and exploded in a Quebec town, killing at least 15.
>
> *http://www.bbc.co.uk/news/world-us-canada-23264397*<http://www.bbc.co.uk/news/world-us-canada-23264397>
>
> Prof. Peter Bernard Ladkin, University of Bielefeld and Causalis Limited
>
> On 11 Jul 2013, at 04:03, Matthew Squair <*mattsquair_at_xxxxxx > wrote:
> Bigger picture is that there's been a modal shift of oil transport to rail
> due to restrictions on pipeline construction, which drives a greater
> operational tempo in rail movements in turn.
>
> On Thu, Jul 11, 2013 at 6:44 AM, Gergely Buday <*gbuday_at_xxxxxx > wrote:
> *http://www.bbc.co.uk/news/world-us-canada-23264397*<http://www.bbc.co.uk/news/world-us-canada-23264397>
>
> Rail World boss Ed Burkhardt: "It is very questionable whether the hand
> brakes were properly applied. In fact I'll say they weren't". [...]
>
> "He said he applied 11 hand brakes. We think that's not true. Initially we
> believed him but now we don't." [...]
>
> The fire department and the train's owners have appeared in recent days to
> point the finger at one another over the disaster.
> - Gergely
>
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