The creation of easements for overhead power lines at multiple sites in
Canterbury, New Zealand.
The jobs involved the surveying of power poles and their stays, with the
creation of easements a certain width from the centre of the power poles and
including areas covering the anchoring stays and blocks. Generally, these were
reasonably long runs (up to 50 power poles with stays at every significant bend
. This meant that calculating the easement lines and entering the data into a
traverse spreadsheet for importing into Landonline was quite time-consuming.
The approach in the field for surveying the poles differed for each staff member
– some would do a single offset shot, some would take two shots equal distance
either side of a pole, and some would observe four points around the pole. The
stays were always measured as a single point where they enter the ground, and
always connected to the pole at the top.
As a result, calculations involved the creation of a string for the main
centreline of the power line, creation of the string representing the stay. The
required lines would then be calculated by offsetting or extending these strings
as necessary, splitting them wherever they crossed existing boundaries in a
traverse spreadsheet. The strings were then traced into the traverse spreadsheet
and unique identifiers typed into the traverse spreadsheet for each point
A macro was written which carried out all of the abovementioned calculations,
except for the tracing of the strings into the traverse spreadsheet - i.e. the
macro calculates the power pole centreline and stay strings, creates the strings
for the easements and assigns a unique identifier to each of the vertices,
calculates the intersections with the boundaries in the traverse spreadsheet,
and splits the strings as necessary.
The macro resulted in a considerable time saving for the firm, as the
calculations could all be completed in the time it took to fill in the macro
fields. The client was very pleased with this expedited process.
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