Land Surveyor Community Forum

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  • Dear friend,

    care to be taken to conduct these kind of surveyors.

    1. ensure that the instrument does not have any errors. this can be ensured by conducting 3 peg test.

    2. Always take the three wire readings.

    3. The staff man should be trained on the importance of holding the leveling staff firm and straight.

    4. Make sure that the readings entered in the field book are correct, may by reading it a couple of times.

    5. Its preferable to reduce the readings in the field book so that the Back sight and fore sight readings have the same reduced level(RL) or within permissible limits.

    6. The Instrument should be placed in such a way that the readings taken on both Back sight and fore sight is approximately the same distance.(This eliminates any minimal collimation errors.

    7. place the instrument in such a way that traffic or human traffic is minimum. If it is in the traffic area then take extra measures for the safety of men and instrument.

    8. Do not work when the sun is on peak as during these hours the staff readings can be blurred or not clear due the heat waves., the Ideal time is during early hours in the morning and evening.

    9. Do not go to site work the next day if all the field data is reduced and closed on known bench marks.

    10. check whether the closing error is within acceptable limits. if not repeat the survey. generally it is 6 Root x K for higher accuracy works and 12 root x k for lesser accuracy works. K stands for length in km.

    Regards

    A Murali babu

     

    • Thanks for your reply
      • they make hand held bubbles to temporarily place up against the level rod for on those days when your rodman has a case of the weeble-wobbles.

        also don't forget to hit the refresh button on the level before every reading

  • A very big thank you for your replies and the link shared.They have helped me a lot.
  • It depend on the precision that you need, or more exactly the work requiered. There are several level of precision, each one with a equipmnet and procedures specifics. If you name it "geodetic leveling", is better to go to a seriuos document as the Mr. Cavell refers at NGS. https://www.ngs.noaa.gov/FGCS/tech_pub/Fgcsvert.v41.specs.pdf http://www.icsarchive.org/tp/5526d-1942_geodetic_surveying_4.pdf Ing. Daniel Acuña , Costa Rica

    https://www.ngs.noaa.gov/FGCS/tech_pub/Fgcsvert.v41.specs.pdf
  • See:  https://www.ngs.noaa.gov/heightmod/Leveling/index.shtml
    JAC

    National Geodetic Survey - Geodetic Leveling
    • Thats a great link. I've used both of the first two methods and agree with the accuracy in that order. I've never had to resort to the third but its how i was initially taught to understand the concept of elevation.  I started surveying in the mountains so elevation was much less critical than in broad flood plains.  Plus it would take so many setups to carry an elevation over a substantial grade. I miss  mountain surveying, none the less...

      National Geodetic Survey - Geodetic Leveling
    • Hi Mr. Cavell,

      Just wanted to tell you, I have enjoyed reading your On the Level.

      Look forward to it each month.

      Billy

      National Geodetic Survey - Geodetic Leveling
      • Thank you, sir.

        National Geodetic Survey - Geodetic Leveling
    • The choice of change points is critical. I tell my chainperson a change point must pass two tests. First if you kick it and it does not move, fine. Secondly if, when you place the staff on the change point and spin it around, it pivots on the same spot, fine.

      If it moves when you kick it it is obviously unstable and therefor unsuitable. When you spin it and it 'walks away' then it doesn't have a definite high point and you would not be measuring to the same point.

      Also, it is a good policy to include three published marks in the level run. You could also get your local blacksmith to knock up one of these for you but beware, they don't pass the first test!

      National Geodetic Survey - Geodetic Leveling
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