StarNet v6 manual - Engineering Surveyor

Chapter 4 Options
Leveling Observations Group: Standard Error Settings
If you have differential leveling observations in your network, you set the default
weighting for these observations here. Weighting for differential leveling is based on
either a standard error per unit length or a standard error per turn.
� Sections as – Select whether you want the “length” numerical value in your leveling
observation data lines to be interpreted as linear length or number of turns.
� Elev Diff – Enter the standard error per unit length or standard error per turn you
want assigned to your elevation difference observations.
When sections are defined as “Length”, the standard error per unit length value is based
on current project units. Therefore:
If units are Feet (US or Int), the standard error per unit length is in Feet/Mile.
If units are Meters, the standard error per unit length is in Meters/KM.
If units are anything else, the standard error per unit length is in Units/Unit.
When sections are defined as “Turns”, the standard error is in Units/Turn.
So, how is the total standard error of a level line between two stations computed?
The total standard error is propagated based on the number of “sections” in the level line,
and as indicated above, these sections are defined as Length or Turns.
Below are two examples, one based on sections entered as Length, the other as Turns.
1. Sections Defined as Length: Project units are in FeetUS, therefore standard error per
unit length is in FeetUS/Mile. So for a level line distance of 25,000 FeetUS between
two stations and an assigned standard error per unit length of 0.015 FeetUS per Mile,
the total elevation difference standard error for the level line will be:
StdErr = 0.015 FeetUS/Mile x SQRT(25,000 FeetUS/5280 FeetUS/Mile)
StdErr = 0.015 FeetUS/Mile x SQRT(4.7348 Miles) = 0.0326 FeetUS
2. Sections Defined as Turns: Project units are in FeetUS, therefore standard error is
based on FeetUS per Turn. So for a level line having 35 turns between two stations
and an assigned standard error of 0.008 FeetUS per Turn, the total elevation
difference standard error for the level line will be:
StdErr = 0.008 FeetUS/Turn x SQRT(35 Turns) = 0.0473 FeetUS
An inline option “.LWEIGHT” is available if you need to change the default weighting
and the type of weighting (section length-based or turn-based) anywhere in your data.
See “Inline Options” in Chapter 5 for details of its use.
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