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LECTURE №4

MEASURING HORIZONTAL DISTANCES

4.1 Introduction
The tasks of determining the horizontal distances between two existing points
and of setting a new point at a specified distance from some other fixed position
are fundamental surveying operations. The surveyor must select the appropriate
equipment and apply suitable field procedures in order to determine or set and
mark distances with the required degree of accuracy.
Depending on the specific application and the required accuracy, one of several
methods may be used to determine horizontal distance. The most common methods
include pacing, stadia, taping, and EDM. Here, we will try to see the rough
distance measurement by pacing and by using a measuring wheel. Stadia is an
indirect method of measurement that makes use of a transit, leveling and
trigonometry.
Taping has been the traditional surveying method for horizontal distance
measurement for many years. It is a direct and relatively slow procedure, which
requires manual skill on the part of the surveyors.

4.2 Rough Distance Measurement
In certain surveying applications, only a rough approximation of distance is
necessary; a method called pacing, or the use of a simple measuring wheels, may
be sufficient in these instances, e.g. locating topographic features during the
preliminary reconnaissance of a building site, searching for the property corners
etc. In this method, distances can be measured with an accuracy of about 1:100 by
pacing. While providing only a crude measurement of distances, pacing has the
significance advantage of requiring no equipment. It is a skill every surveyor
should have. Pacing simply involves counting steps or paces while walking
naturally along the line to be measured.

Distance = Unit Pace × Number of Paces

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