Best Practices For Acceleration And Stopping Distance?

Discussion in 'TSW General Discussion' started by Jon from Rhode Island, Oct 26, 2021.

  1. Jon from Rhode Island

    Jon from Rhode Island Well-Known Member

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    Do the various carriers (DB, etc) maintain rules and regulations regarding brake settings on approach to station stops, acceleration limits, and other similar passenger comfort/safety best practices? Are these compiled somewhere?
     
  2. lcyrrjp

    lcyrrjp Well-Known Member

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    In the UK it varies from operator to operator, with some being more prescriptive than others. Most of the rules/guidance in place is there to reduce the risk of operational incidents, but in some cases giving a comfortable ride is a factor too.

    Some of the guidance I’m aware of being in place with one or more operators is:

    - no more than 20mph when 200m from a red signal (as a guide, the AWS ramp is normally 183m from the signal). For freight operators this is sometimes 15mph when 200m from a red signal.
    - brake in step 1 when coming to a stand (i.e. just the very final part of the braking, as it gives a more comfortable stop). On a train with a brake without steps (such as the class 101), try to stop on a rising brake - i.e. the vacuum should be rising, not falling, as you come to a stand.
    - when starting, don’t go straight to full power, but advance the power progressively. This varies between trains. With a sprinter (e.g. class 150) for example it is no more than Step 4 at 5mph, and Step 7 (full power) at 10mph. On some trains you can go straight to full power if adhesion is good enough. This normally applies on modern EMUs such as those on the Brighton mainline.
    - some operators have a maximum speed at the platform ramp (when entering a platform). At one operator I’m aware of that being 15mph, but that’s unusually low. If you’re in a modern unit and are going to the end of a 12-car platform, 40mph with the brake in is perfectly possible with good adhesion, but 30mph is more usual.
    - when running on 4 aspect signalling, the speed passing the single yellow must be no more than half the line speed, with the brake in.
     
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  3. Clumsy Pacer

    Clumsy Pacer Well-Known Member

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    In the UK, don't use full service braking unless absolutely necessary.

    Tell that to drivers on the Durham Coast Line ;)
     
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  4. Lamplight

    Lamplight Well-Known Member

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    For Germany
    Only things that come to my mind right now are these:
    • General limit for acceleration is 1m/s^2
    • Get a (passenger) train rolling with <20kN per traction motor before increasing force to 40-50kN per traction motor
    • Start a freight train with no more than 40-50kN
    • Release the brakes shortly before stopping so that no more than 0.5 bar brake cylinder pressure is applied at the moment of stopping
    There are probably tons more for specific locos/trains, but these are some general guidelines/rules I know of.
     
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  5. Blu

    Blu Active Member

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    The British 3 step brake is pretty forgiving in commuter runs. But you need to take into account weather conditions. You can approach a stop at speed and brake down pretty quickly. However here is a vid of the 3 step brake and WSP going wrong with 1B47.
     
    Last edited: Oct 27, 2021
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  6. lcyrrjp

    lcyrrjp Well-Known Member

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    Indeed - as I say, the policies I mention are in place with some UK operators but not all, so there will be variation. I don’t know what Northern’s policy is on this.
     
  7. lcyrrjp

    lcyrrjp Well-Known Member

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    A good point about driving economically (‘Eco-driving’ as it’s referred to where I work). One of the things some operators instruct is that, when maintaining the train at line speed, rather than selecting the power notch which will maintain a steady speed (as you might expect) you should use full power until you reach the line speed, then shut off power completely. Wait until speed drops to about 5mph below line speed, then take full power again up to line speed, and so on. Effectively, use the power controller as an on/off switch. Apparently research shows that this power-and-coast method (known as ‘pulse and glide’ when used by car drivers) actually uses less energy than maintaining a steady, lower level of power.
     
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