The Smiler Incident - What Happened

Discussion in 'General Discussion' started by Rob, 22nd Apr 2016.

  1. punks

    punks TowersStreet Member

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    How could I get my hands on a copy, Dan?
     
  2. JB1985

    JB1985 TowersStreet Member

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    Good find would be good to se the whole report
     
  3. Dan

    Dan TS Contributor

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    I'll try and get a copy uploaded next week. Just need to find a working scanner
     
  4. punks

    punks TowersStreet Member

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  5. Dan

    Dan TS Contributor

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    The Steven Flanagan report has already been released. The Factual report is one of the documents I have so at least I don't need to scan that one in :)
     
  6. punks

    punks TowersStreet Member

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    250 odd pages isn't it?! Blimey...
     
  7. Jared

    Jared TowersStreet Member

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    Briefly scanned a few parts of the witness report. It says that, according to the manufacturer, for a train to be registered as entering a block only ONE of the TWO switches needs to be actuated for a positive response ('OR' logic) yet for a train to be registered as having left a block, BOTH switches must have been actuated for a positive response ('AND' logic). Why the difference? Why are they requiring only 1 switch for entering but both for exiting? I'm not sure I understand that logic.
     
    Last edited: 7th Jan 2017
  8. MattyH

    MattyH TowersStreet Member

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    Presumably one at the entry of the block and one at the exit? so to Enter it passes the entry point switch but to exit is has to pass both the entry and exit switch.
     
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  9. Jared

    Jared TowersStreet Member

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    That would make sense but that's not how the report reads. It says there's a pair of proximity sensors at the start of a block, and a pair at the end. Yet on entry, only one sensor must be actuated on entry for the train to register as within the block. But both sensors on exit must be triggered.

    From witness report:
    "i) entry of a train into a block is monitored by a pair of proximity switches, and a signal from at least one of the switches is sufficient for the control system to regard the train as having entered the block, and ii) exit of a train from the block is monitored by a pair of proximity switches, and a signal from both of the switches is required for the control system to regard the train as having left the block. This demonstrates the correct approach to ensuring safety through 'redundancy', using 'AND' and 'OR' logic in the control system appropriately, i.e. OR logic for situation i) above, and AND logic for situation ii) above."

    Why even have two switches on entry if you're only requiring a response from one? In this context, what does "safety through redundancy" mean exactly?
     
    Last edited: 7th Jan 2017
  10. DiogoJ42

    DiogoJ42 TowersStreet Member

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    Backup in case one fails?
     
  11. Jared

    Jared TowersStreet Member

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    Sure, could be the case. But that would only apply to the entry switches, as there's two of those but only one is required. Whereas both exit switches must be activated for the train to register as having left the block. Meaning there's no backup for the exit condition. Maybe this is just the way it's designed and I'm digging into it too much. It just struck me as odd.
     
  12. Katy

    Katy TowersStreet Member

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    It's to cope with a sensor triggering by mistake, or failing to trigger when the train passes over. Means it should always fail safe with a train in block error rather than thinking the block has cleared when it hasn't.
     
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  13. AndrewH

    AndrewH TowersStreet Member

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    As when the train is entering a block it is essential that it triggers the sensor so if either is triggered it must show as occupied. When leaving the block it is vitally important that the train definitely exits that block hence the requirement for both sensors to be triggered to ensure it has definitely left.

    Also did anyone else notice it said the crash happened in the cobra roll element? Erm did it not happen in the batwing?
     
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  14. Matt.GC

    Matt.GC TowersStreet Member

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    It's more cautious that way. It would take just one sensor to detect a train going into a block (I.E in to potential danger) but would require a more than one to confirm it has definitely left a block (away from potential danger and in to safety). If you think of it like that, it actually makes perfect sense.
     
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  15. Dan

    Dan TS Contributor

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    Here is the additional reports I have received. It contains the following
    • Witness statement 1 from an electrical engineer who worked on the smiler talking about his role and procedures but not about the accident
    • Witness statement 2 from the same person (All other witness statements were redacted)
    • The daily ride report sheet from the day of the accident
    • Executive summary of HSL report ES/2015/70
    • Executive summary of HSL report MH/15/190
    • BRE wind report (I haven't scanned the pages with the raw data)
    I have asked the Health & Safety Laboratory for their full reports and will let you know if I get anything from them.

    Contains public sector information licensed under the Open Government Licence v3.0.
     
  16. Skyscraper

    Skyscraper TowersStreet Member

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    i have to say that the witness statements were very interesting to read, as I'm interested in the technical side of roller coasters.
     
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  17. GaryH

    GaryH TowersStreet Member

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    Its a pretty shocking report when you read through it all.

    Page 13, Item 28 sounds a bit worrying:

    "Post incident no evidence was found that the track itself was defective. The Smiler underwent an independent examination by Jacobs Engineering which found gaps in the track which were larger than would normally be expected but (in the opinion of Jacobs engineers) would not contribute to reducing the speed of the train."

    Gaps in the track larger than to be expected...... so the next accident waiting to happen then, part of the track section coming apart and shearing the bolts off?

    Also, page 14.

    "36. The two electrical maintenance engineers who performed the block reset on the Smiler on the day of the accident had not seen / been appraised / given any formal training or written procedures for how to go about performing a block reset.

    37. The two electrical maintenance engineers in question had not seen any risk assessments for the Smiler ride.

    38. The four engineers who attended the Smiler on the day of the incident had not seen and/or not read Gerstlauers Original Operating Instructions."


    Pretty shocking. I would have thought Towers to be much better on training than this.
     
  18. andeyhart

    andeyhart TowersStreet Member

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    If there was any type of accident still waiting to happen, then there's no way on this planet H&SE would have allowed the ride to re-open. The ride is perfectly safe. Even the judge stated in his closing statements during the trial that the ride itself was perfectly fine.

    During last closed season, there were pictures that surfaced of the ride with scaffolding surrounding parts of the track, so I'm sure any structural problem would have been dealt with before the ride reopened.
     
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  19. GaryH

    GaryH TowersStreet Member

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    True but isnt there an issue with the foundations in this area - if so that could potentially cause some of the gaps in the track to open up?
     
  20. andeyhart

    andeyhart TowersStreet Member

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    Possibly, but I doubt it would be enough of a problem for there to be a serious issue. As terribly inept as Towers/Merlin were in the events leading up to the crash, I sincerely believe they've learnt their lesson in this respect.
     

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