Minimum Elevation Misclo

Minimum Elevation Misclosure in mm

 Classification

Elevation Closure

  First-Order, Class

4√K

  Second Order, ClassII

8.4√K

  Third Order

12√K

  Control levelling
  (used in Building Studies)

24K

√km = square root of distance in kilometers


Level Run Accuracy

The National Mapping Council of Australia has published standard specifications and recommended practices for vertical control surveys. These surveys must conform to the following standards of accuracy:
  • First Order: Differential levlling. Misclosure not to exceed mm       ► 4 √k
       (where k is the distance in kilometres of a circuit or between bench marks)

  • Second Order: Differential levelling. Misclosure not to exceed mm ► 8.4 √k.

  • Third Order: Differential levelling. Misclosure not exceed mm         ► 12 √ k.

  • Fourth Order: Sufficient to control contouring of the area to be mapped either by differential,     trigonometric levelling.

    First Order Levelling. Very little first order levelling is carried out due to the high cost.

    Second Order Levelling for the establishment of primary bench marks.

    Third Order Levelling for the establishment of other registered bench marks.

    Control Levelling to evaluate temporary bench marks for minor projects.

    Please make sure you have you are within misclosure limits for Project 3

    Reference:
    http://www.surveyorsboard.vic.gov.au/documents/surveypracticehandbook/SPH_S2_Sect8.pdf

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