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Thread: Gradient question

  1. #1
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    Default Gradient question

    I'm working on some route features based on a local line. How do I convert local gradient terminology [i.e. 1:50} into the scale used in surveyor?

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    1:200 0.5%, 1:100 1%, 1:50 2% and so on

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    Quote Originally Posted by grazlash View Post
    1:200 0.5%, 1:100 1%, 1:50 2% and so on
    Thanks. Presuming then that the height value on the track [advanced] tab is the percentages? A 1:33 Grade would be 3.0 on the surveyor tool? [Otira Tunnel, NZ]
    Last edited by Concrete_Bob; April 7th, 2020 at 09:57 PM.

  4. #4
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    Quote Originally Posted by Concrete_Bob View Post
    Thanks. Presuming then that the height value on the track [advanced] tab is the percentages? A 1:33 Grade would be 3.0 on the surveyor tool? [Otira Tunnel, NZ]

    That is exactly what grade is in the Otira Tunnel and it's 8.5 kilometers long. So if you are doing a prototypical route of the west Coast that is what you should be using. Steam locos are not allowed in the tunnel unless they are under light steam i.e. being towed by electric locos.

    Cheers,
    Bill69
    If you are going to try cross-country skiing,
    Start with a small country.



  5. #5
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    Get the "Optical-Grade-Chart" which you can probably google, as I did. Hm, not sure how I found it. Same source but a not as neat pdf, https://surveyequipment.com/assets/i...wnload/id/101/

    If it doesn't like the link, the source is surveyequipment dot com.

  6. #6
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    Quote Originally Posted by Bill69 View Post
    That is exactly what grade is in the Otira Tunnel and it's 8.5 kilometers long. So if you are doing a prototypical route of the west Coast that is what you should be using. Steam locos are not allowed in the tunnel unless they are under light steam i.e. being towed by electric locos.

    Cheers,
    Bill69
    No electrics on the midland line, DX diesels , with an extra 4 bankers on the tunnel gradient.

  7. #7
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    Awesome help thanks. Not going full prototypical, just looking at the tunnel as a benchmark for extreme gradient scenarios.

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    Quote Originally Posted by Concrete_Bob View Post
    No electrics on the midland line, DX diesels , with an extra 4 bankers on the tunnel gradient.

    Ah! You are right, the electrics were removed about eight or nine years ago.

    Cheers,
    Bill69
    If you are going to try cross-country skiing,
    Start with a small country.



  9. #9
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    Some really cool reading about the tunnel - Apparently, around 80 tonnes of sand is dropped in the tunnel every year.

    http://www.rmtunion.org.nz/publicati...port-Final.pdf

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    Having read most of the documentation provided on the Otira tunnel, I just have the following comment or question: Who's brilliant idea was to eliminate electric traction at this line? Money? Looks like diesel on the long run is way most costly. Or the diesel loco salesman was pushing his products above common sense.

  11. #11
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    It was a 10 km section of electrification on a 212 km line, put in place specifically to resolve the issue of excessive smoke from steam locomotives in the tunnel. The last electric locos were purchased in 1968. By 1988, increased volumes of coal freight and larger consists meant that there were not enough units in service at any time to haul a full coal train up the incline. Switching to diesel bankers meant that the two locos used on the eastern side of the tunnel could remain coupled and continue the western side, and vice versa.

  12. #12
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    Quote Originally Posted by Concrete_Bob View Post
    It was a 10 km section of electrification on a 212 km line, put in place specifically to resolve the issue of excessive smoke from steam locomotives in the tunnel. The last electric locos were purchased in 1968. By 1988, increased volumes of coal freight and larger consists meant that there were not enough units in service at any time to haul a full coal train up the incline. Switching to diesel bankers meant that the two locos used on the eastern side of the tunnel could remain coupled and continue the western side, and vice versa.
    This sounds just like the Hoosac Tunnel. it was electrified in 1910 and the wires came down in 1946 and put in for exactly the same reason. This was the only electric section on the Boston and Maine and by the time the diesels came along that were worthy, the ca. 1910-1911 electrics were a bit worn out. A new set of EMD FT-units put the electrics on the scrap line.

    Getting back to topic. This is rise over run, the same as working out slope in geometry. My driveway works out to be about 12.5% and I don't leave the house in snowy weather!
    John
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    If you find the top of the grade, and the bottom of the grade, and using "Hold Shift" and place a single track (off to the side) "sort of" connecting the 2 points (making sure to measure and apply the top and bottom grade spline point height numerals), then draw arrows from each spline point, to that track, making certain that they intersect at exactly 90 degrees, then place a spline point on that temporary track where the arrow intersects, measure that spline point height and lock that numeral in, Erase the spline point every time, after measuring it, and locking the numeral in, then apply that height to the grade spline point. Do this for the entire grade, no matter how twisting and turning the track slope is. Always remember to: Erase the spline point every time, after measuring it, leaving no more than the 1 top, and the 1 bottom, spline point on the temporary track.
    Last edited by MP242; May 2nd, 2020 at 12:52 PM.
    My apologies to all. I have decided that in these horrible current events, we all need to stick together as a Community

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