Noob Question On Distance Until Speed Change

Discussion in 'TSW General Discussion' started by hodrim, Jun 8, 2022.

  1. hodrim

    hodrim New Member

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    Hello everyone. It's my first time playing TSW2. I went straight into the german route "Schnellfahrstrecke Köln-Aachen". I only played two scenarios so far and there's something confusing me a bit.

    So, yes, the HUD has a marker that shows the current speed limit. On the top right of the screen you can see the distance until speed change. However, once you reach that distance the HUD below doesn't immediately update with the new speed limit.

    I wanted to understand this a little bit better. That countdown distance is for a signal, right? The speed changes once I reach that signal or there is something else around I should look to visually know that the speed has changed (that is, if I'm not looking at the HUD). How does that work?

    Should I ignore the marker on the HUD and orient myself through the countdowns? Is the HUD not updating immediately when I reach the signal some kind of a bug?

    Thanks.
     

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  2. Mattty May

    Mattty May Guest

    The new speed limit, if faster, applies to the back of the train. So, the whole train has to pass the faster speed limit marker before the faster speed can take effect. If a lower speed limit applies, the lower speed applies immediately to the front of the train.
     
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  3. hodrim

    hodrim New Member

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    Aah, that makes perfect sense. Thanks!
     
  4. rennekton#1349

    rennekton#1349 Well-Known Member

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    Only exception to the rule is the underground section of the bakerloo line. The speed increases from the front of the train so the driver can speed up faster and run the tight schedule and stuff. It is the same with lower speeds. Once you get to overground, back of the train needs to pass to increase speed. Front for lower speed
     
  5. ARuscoe

    ARuscoe Well-Known Member

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    Almost all speed limits apply to the whole vehicle, though when we're driving a car for example we tend to speed up to "meet the new limit" though this is technical incorrect.
    In game the new limit only applies once the whole vehicle has passed, hence the HUD doesn't update (and it allows for different vehicle lengths too. You can monitor this by changing to the external view, rear (press 2 twice on the keyboard) and you'll see the HUD only changes when the back of the whole consist passes the speed board

    As rennekton#1349 says the exception to this is the London Underground where they use the front of the train as the speed marker. I would imagine this is because they don't have to deal with many different lengths of train so they can tell when the back of the train would have passed and just put the signal at the front

    One cool result of the back of the train being the marker is that on some trains (especially freights) you can have a train length system where you press a button as the FRONT of the train passes the speed board, and when the computer onboard works out when you've cleared the correct length of track (And thus able to speed up) you get an audible BEEP. The class 66 IRL has this, not sure if it's in game though
     
  6. Clumsy Pacer

    Clumsy Pacer Well-Known Member

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    It is. It's also on the BR 182.
     
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  7. At a guess I reckon that rule was put in place mainly for junctions. As the train needs to be clear of the junction before it accelerates or there's a possibility of derailment.

    Well here in the UK anyway. Where the railway infrastructure was ancient right up until not that long ago.

    One of my local lines was still operating on semaphore signals in 2005!
     
  8. ARuscoe

    ARuscoe Well-Known Member

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    There are several factors which require trains to change speed including
    • Junctions - changing direction puts lateral forces on components which are weaker than a straight rail
    • Tight bends - changing direction puts lateral forces on rail and track bed components
    • Weak bridges or foundations - a heavy train can cause issues for the ground itself where said ground hasn't been strengthened
    • Areas where signals are closer together - slower speeds with tighter packed signals near major stations can allow for higher throughput of trains
    In the first three cases at least you would need to make sure that the issue has been passed by the whole "possible cause", ie the whole train (even though in many cases the thing which would cause the most harm would be a great big loco, normally at the front)
     
  9. I ment the reason the back of the train has to pass the speed board before the limit changes.
     
  10. stujoy

    stujoy Well-Known Member

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    It’s just common sense. If a section of track can only safely be used below 30 mph then all the train has to obey that limit. If the next part of the line has a 60 mph limit then it is only safe to speed up when the train is fully in that section, which only occurs when the back of the train passes the sign. Trains are long and also vary in length, so the only place they can realistically put the sign is at the point where the actual limit changes, except on the underground where the signs for higher limits are placed one train length beyond the actual place of the change because all the trains are the same length, so when the driver passes the sign they are safe to go faster.
     
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  11. FD1003

    FD1003 Well-Known Member

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    I think at its core the issue is that if the locomotive needs to go at that speed on this particular part of the track, the same is true for the last wagon.

    Usually max speed on curves is dictated by passenger comfort (or cargo not having to endure too much centrifugal force - actually inertia) - tilting trains can go faster on curves without any changes to infrastructure - so it makes sense you don't want to accelerate until the whole train has passed the speed limit change point

    In case the speed limit is in place due to structural limitation of the rolling stock or infrastructure, the concept that each part of the train has to pass that particular point at that speed is even more important.

    With some modern EMUs they can accelerate quite quickly and with a 8-12 car consist you could end up going quite a lot faster by the time the end of the train has passed the speed limit change point.
     
    Last edited: Jun 11, 2022
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  12. ARuscoe

    ARuscoe Well-Known Member

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    So did I, I was just pointing out some of the "why"
     

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