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Thread: Autopilot - Cruise Control

  1. #1
    Join Date
    Jun 2009
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    Oshawa ON
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    Default Autopilot - Cruise Control

    Hello all, just a question - question.
    Why does Open Rails Autopilot keep the speed of the train below the Posted Speed? Yeah, all the stuff about OR using the AI values in Autopilot but why does the train never reach the "Posted Speed"?

    Using Regular Mode and having to operate Throttle/Brakes/Dynamics I can usually keep up the speed. I like the Autopilot mode to just look at routes, like a passenger. I wish I could do this in my car! I worked at On-Star for 12 years, we had people complaining that the Cruise in their car didn't work! If they took their hands off the wheel the car would go where it wanted! AND would not stop when needed! (Now in 2020, vehicles have circumvented some of these situations)

    My "Train" is on Tracks that guide it. Why does OR keep the speeds below the posted speeds on a given route?

  2. #2

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    Don,
    Yes, I've noticed it, too. However as a (nerdy) retired engineer I noticed that the maximum speed attained is always pretty close to 97 % of the posted speed & that full power acceleration to this speed starts to throttle back upon reaching 85 % to 95 % of the posted speed. These margins have probably been chosen by the Open Rails programmer to avoid the speed-control algorithm over-shooting the speed limit as well as to reflect that most train timetables expect train speeds to be a bit less than full speed to provide make-up time when running late &, given speed recording equipment, it's a manner in which many drivers might normally drive, if not slightly slower.

    Note also, that typically in the past it was considered a "good practice rule of thumb" for timetables to be designed with 6 % to 8 % margins for make-up time to recover late running. So for Open Rails to initially drive trains at 97 % of maximum speed boards would reflect how many drivers might drive trains running normally to a timetable, with this being a useful programmed, driving-simulation method for Open Rails' first attempt at automatic driving in "timetable" mode. In timetable mode you can now specify a "cruising" speed until a train becomes "X" minutes late where-upon it drives to the maximum allowed.

    By the way, my local suburban train system a few years ago had "professionals" dumb-down the timetable to have as much as 10 % margin for make-up time (I suspect because of "Key Performance Indicators" driving their income or job prospects given the political heat of late running trains). The extra margin has not improved on-time running but has driven a culture of slow, easy going driving such that many drivers do not seem to know how to to make up lost time despite the huge margins provided. We actually had more frequent & better on-time running statistics 30 years ago with with a greater proportion of less reliable old trains & a new fleet with many teething troubles, but today's figures accept a greater number of minutes delay before being recorded as late.

    Cheers, 'n' tears, Mark.

  3. #3
    Join Date
    Mar 2011
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    MP44.2 Worcester, MA
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    175

    Default

    Another reason for this is that OR may be trying to simulate the "3mph rule". I once asked an engineer why I always heard the AMTRAK coming through the speed detector at 62 mph and freight at 42 mph when the posted speed limits where 65P/45F. He explained that you never exceed 3 mph below the posted speed limit. Exceeding that speed could get you a written warning or even sent back for retraining.

    Fred

  4. #4
    Join Date
    Jun 2009
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    Default

    Thank you Mark and Fred for those answers. That is kind of what I thought, related to Prototype Running.

  5. #5

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    Hi Don,
    Additionally, autopilot uses inaccurate acceleration rates so if your planning timetables you'll get way too early arrivals, especially if there are significant gradients on the route.

    Case in point: On the PRR-East v2 route I released a while back the timetable for the run from Altoona to Pittsburgh is way off.
    I'm slowly working up a fix for this. A good illustrative example is the run from Altoona up the grade through Horseshoe Curve to Cresson at the top of the grade. In autopilot mode the player holds MAS all the way up the grade but in manual (normal) mode I can't get over 35 MPH! Using manual mode during all acceleration from stations and running up grade will give me a fairly accurate speed while level and downgrade running. It's just the acceleration and power running up grade that gives wrong speeds for planning an accurate timetable.
    This is NOT a complaint about autopilot. It's a wonderful feature for checking routes and sitting back and watch incredibly complicated AI traffic running and a little care in TT planning is all that's needed to get the right timing for station stops.
    Just my 2p.

    regards,
    ............Vince ..............
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  6. #6

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    I believe you need to set the activity services efficiency from 75 to 100%, to achieve full line speed or maximum speed of the Consist. I could be wrong but try it and see.
    Thanks

  7. #7

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    G'day, could you please tell us where the "activity services efficiency" is located?
    Regards
    Barrie

  8. #8
    Join Date
    Feb 2013
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    Default

    Quote Originally Posted by gremlin1812 View Post
    G'day, could you please tell us where the "activity services efficiency" is located?
    Regards
    Barrie
    Barrie, I think you'll find that in the services file (.srv )
    Cheers, R. Steele [Gerry] It's my railroad and I'll do what I want! Historically accurate attitude of US Railroad Barons.


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