Level Crossings In Sehs (an Explanation)

Discussion in 'TSW General Discussion' started by Shaun123, Feb 1, 2021.

  1. Shaun123

    Shaun123 Well-Known Member

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    So for those wondering;

    One of things I’m still impressed with is the level crossings. Not just extremely true to life, it is what happens in reality. Personal experience from the day job the following happens;

    Note there are automatic and manual CCTV crossings, Modern manual ones are lowered and raised by “Crossing Keepers” within a signalbox/signalling centre.

    For example on the restrictive aspects approaching Gillingham, this is because the Level Crossing is “Raised”

    As we are approaching the station or enter the station itself we approach a “Strike In” point - this may be a treadle on the ground which is linked to the track circuits.

    When the train hits this strike in point, a CCTV picture appears on the Crossing Panel (if it’s a manual crossing) for the barriers to be lowered, once this is done you then get “Crossing Clear” which then means the signal ahead can step up to a proceed aspect.

    So level crossings and signalling system are intimately linked.

    Automatic half barrier crossing work in the same way, minus the crossing keeper.

    This is represented excellently within game.

    Thought this would help those interested.
     
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  2. Smograil

    Smograil Member

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    Good explanation. However if AHBCs have been modelled they shouldn't be interlocked with signals. One of the key risks around this type of crossing is that they aren't interlocked and work off treadles. Been a signaller and signal manager for 15 years and I personally dislike working with them for that reason

    That said, Kent isn't an area I am familiar with operationally and I don't know if there even are any AHBCs on this route
     
    Last edited: Feb 1, 2021
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  3. Shaun123

    Shaun123 Well-Known Member

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    Yep, sorry that’s what I meant!

    Where I work we have one AHB, that is near a station and also has a signal at the end of the platform which is why it works similarly to as I said, with the treadle within the station limits.
     
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  4. L89

    L89 Well-Known Member

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    I'm wondering what happens when a train doesn't need to stop at the station near the level crossing but continues on. Wouldn't the aspect be green here so technically the crossing will stay up in the game? Maybe it isn't an issue with the timetable services but for scenario designer it could be.
     
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  5. Winzarten

    Winzarten Well-Known Member

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    The train signal before the crossing stays red until the crossing is down, as the track block is not free until the crossing is down. That means that the crossing will be closing the moment the dispatcher tries to clear you onto track block, and the light will move from red once the crossing is down.
    So the crossing will be down long before you cross it.
    This also means that the crossing might stay down after you pass it, as another train might be already cleared onto the track from opposite direction.
     
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  6. aaron1807

    aaron1807 Member

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    Matt said in the stream last night that the level crossing has been set to remain down in scenario planner, but in service mode it's programmed to work correctly as all services stop there.
     
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  7. Smograil

    Smograil Member

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    Presumably that has a stopping and non-stopping mode? Racking my brains here but we had one in a station and you had to press a button depending on if the train was booked to call. Think it activated a separate treadle and the board came off later even though not interlocked

    Got took out years ago though and replaced with an OD so a bit hazy on it now
     
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  8. Shaun123

    Shaun123 Well-Known Member

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    It’s timed, so if there’s station overtime/disruption then the AHB goes into “failed mode” I’ve been on when the driver has had to put the signal back so it resets the AHB in effect, but it’s a bit complicated for me that one!
     
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  9. geloxo

    geloxo Well-Known Member

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    This depends on the type of level crossing, as explained above. When using interlocked ones (the ones where interlocking has info about the status of barriers and full control over those barriers) the signal just before the level crossing won´t clear unless the interlocking has commanded the lowering of barriers and barriers positions are checked by interlocking to be at the correct position as well.

    When using autonomous level crossings the interlocking has no control over level crossing so signals before level crossing could allow train to pass if traffic ahead the block allows that. In that case the level crossing itself has a track circuit/axle counter and as soon as train is detected by the level crossing track vacancy system its barriers will be lowered. A dedicated signal managed by level crossing itself will warn trains in its area about possible failures on barriers and would stop approaching trains if required. They may also have obstacle detection systems (cameras or loops to detect trapped cars between the barriers) so they will also prevent trains to pass the level crossing if it´s not safe to do it, using the dedicated signal too.

    Cheers
     
    Last edited: Feb 3, 2021
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  10. DTG Matt

    DTG Matt Executive Producer Staff Member

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    Just to expand on one point - in scenario planner the gates are still working the exact same way but as someone else noted, they'll be closed the moment the dispatcher tries to clear the block across the gates (for example, beyond the starter at Gillingham heading East) - when that happens you're still a good 3-4 blocks away so you won't see it.

    You CAN see it happen in the signal hud though - e.g. you'll see your next upcoming signal at green, then pass it and you will see the next one is yellow - then a few moments later, it'll pop up to green. That change is EITHER a train ahead of you clearing the section, OR, you're coming up to some gates that took a moment to close and only once they were closed could it lock the block ahead - once that was done, the starter went yellow, the next one went double yellow, and your upcoming signal went green.

    Service mode we've set all the trains to not dispatch beyond until you've stopped, scenario planner can't actually do that - so it will just dispatch beyond in all cases and clear the gates down.

    If you fly WAY ahead of your train in a scenario planner scenario, you'll still see the gates going down, and they should always be down by the time you get to them.

    Hope that helps :)

    Matt.
     
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  11. Jasonic

    Jasonic Member

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    Good to see them operate Matt, they are a bit quick though should be about 20-25 secs on average from start to end.
    It would be good on the East Coastway to see the same applied at Berwick, Polegate, Hampden Park, Newhaven Town and Harbour.
     

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