SURVEYING INSTRUMENTS AND MEASUREMENTS

TYPE OF SURVEYING INSTRUMENTS
1. Theodolite
A theodolite is a precision instrument for
measuring angles in the horizontal and vertical
planes. Theodolites are used mainly for
surveying applications and have been adapted
for specialized purposes in fields like metrology
and rocket launch technology.
A modern theodolite consists of a movable
telescope mounted within two perpendicular
axes the horizontal or trunnion axis, and the
vertical axis.
2. Measuring
Tape
Measuring Tapes are used in surveying for
measuring horizontal, vertical or slope distances.
Tapes are issued in various lengths and widths
and graduated in a variety of ways.
3. Total
Station
A total station is an electronic/optical
instrument used in modern surveying and
building construction that uses electronic transit
theodolite in connection with electronic distance
meter (EDM).
It is used to take the measurement ofHorizontal angles: The rotation of the optical
axis of TS from the instrument north in a
horizontal plane gives the horizontal angle.
Vertical angle: The inclination of the optical axis
of TS from the local vertical gives a vertical angle.
Slope distance: The distance between TS and
the target gives the slope distance.
4. GPS
The Global Positioning System (GPS) is
a space-based satellite navigation system
that provides location and time information
in all weather conditions, anywhere on or
near the Earth where there is an
unobstructed line of sight to four or more
GPS satellites.
5. Chains
Chains are used to directly measure the
linear distance between two points above the
earth’s surface
6. Pegs
Used to mark out residential boundaries and
indicate points and positions of a site
7. Compass
Used to run a traverse line.
8. Prism
A prism is used to reduce the scatter of the
beam as it is reflected to the total which
allows for both more accurate measurement
and a longer range than the measurement can
be made.
9. Tripod
Used to support any one of several surveying
instruments, such as theodolites, total
stations, levels, or transits.
10. Plumb Bob
It is used to transfer the points to the ground
on a slope while chaining. It is also used to
make the ranging poles vertical. In
theodolites, compasses, plane tables, and
other surveying instruments, it is used for
centering purposes.
11. Dumpy
Level
12. Prism Pole
13. Leveling
Staff
14. Arrow
15. Ranging
Rods
A level is an optical instrument used to
establish or verify points in the same
horizontal plane in a process known as
levelling. It is used in conjunction with a
levelling staff to establish the relative
height or levels of objects or marks.
A prism pole can be used to measure
the elevation of a specific ground point by
using a sight level, which is important if
you want to get accurate results. You can
find a survey pole in a variety of materials
— from metal and fiberglass to a variety
of composites.
A level staff, also called levelling rod, is
a graduated feet and meter on aluminum
rod, used with a levelling instrument to
determine the difference in height
between points or heights of points above
a vertical datum. It cannot be used
without a leveling instrument.
Arrows are used for marking and are
made up of hardened, and tempered steel
wire of good quality. 10 arrows are
usually sold with a chain. Its length is
about 25-50 cm. One of its ends is
sharpened while the other end is bent
into a circular loop.
To mark the chain length on the ground,
an arrow is inserted at the end of the
chain.
Ranging rods are 2-3 meters in length
and are painted with alternate bands of
two colors like white and black, red and
white in succession. They are used to
range an intermediate point on a survey
line.
MEASUREMENT
-
process of determining the extent, size, or dimension of a particular quantity in
comparison to a given standard

TYPES OF MEASUREMENTS
1. Direct Measurements - comparison of the measured quantity with a standard measuring
unit (makes use of instruments to measure the quantity)
2. Indirect Measurements - made when it is not possible to apply a measuring instrument
directly to a quantity
THE METER
- proposed in 1789 by French scientists to establish a system suitable for all times and all
peoples, and which could be based upon permanent natural standards.
- originally defined as 1/10,000,000 of the earth’s meridional quadrant
- it was redefined in 1960 as the length equal to 1,650,763.73 wavelengths of the orange-red
light produced by burning the element Krypton (atomic number 86) at a specified energy level
in the spectrum.
 Effective January 1, 1983, the English System was officially phased out in the Philippines and
only the modern metric system was allowed to be used. The metric conversion was signed into
law in 1978 by Pres. Marcos. The metric system prescribed the use of the International System
of Units (SI) as established by the General Conference on Weights and Measures and as
modified by the local Metric System Board to suit Philippine Conditions.
UNITS OF MEASUREMENT
1. Linear, Area, and Volume Measurements
2. Angular Measurements

Radian – SI unit for plane angles (the angle subtended by an arc of a circle having a
length equal to the radius of a circle)
a) Sexagesimal Units - the degree, minute, second
b) Centesimal Units - uses grads (360° = 400 grads)
- the grad is divided into 100 centesimal minutes and the minute is
divided into 100 centesimal seconds
SURVEYING MEASUREMENTS
Measuring distances and angles from a known reference are fundamental surveying
operations. Through the use of trigonometric calculations, the distance and angle measurements
are used to establish three dimensional (3-D) coordinates for each surveyed point. The
coordinates are then plotted to create planimetric maps and digital terrain models (DTM’s).

TYPES OF MEASUREMENTS
1. Direct Measurements - comparison of the measured quantity with a standard measuring
unit (makes use of instruments to measure the quantity)
2. Indirect Measurements - made when it is not possible to apply a measuring instrument
directly to a quantity
The five common types of survey measurements are horizontal distances and angles, vertical
distances and angles, and slope distances.
 HORIZONTAL AND VERTICAL PLANES
Angles and distances are measured relative to either a horizontal or vertical plane. The horizontal
plane is a level surface radiating outward from the point of observation and is perpendicular to
the vertical axis. The vertical axis (or plumb line) is always parallel to the direction of gravity. The
vertical plane runs in a direction parallel to the vertical axis and perpendicular to the horizontal
plane. A vertical plane is established whenever the instrument rotates along the horizontal plane
to face a new direction.
a) Horizontal Distances and Angles
A linear measurement on the horizontal plane determines the horizontal distance between two
points. However, the true horizontal distance is curved like the Earth’s surface. Due to this
curvature, the direction of gravity is different at each point. Horizontal distance and angle
measurements are then used to calculate the position of a point on the horizontal plane.
b) Vertical Distances and Angles
Vertical distances are measured along the vertical axis to determine the difference in height (or
elevation) between points. Vertical angles are measured in the vertical plane either above or below
the horizontal plane of the instrument. Zenith angles, used as a reference for measuring vertical
angles, are defined as 0° directly overhead and 90° at the horizontal plane.
c) Slope Distance
The slope distance is the shortest distance from the instrument to the target. This distance is the
hypotenuse of the horizontal and vertical distances. The horizontal and vertical distances can be
calculated if the slope distance and vertical angle is known.
 ACCURACY AND PRECISION
Accuracy and precision are two different, yet equally important surveying concepts.
-
Accuracy is the degree of conformity of a given measurement with a standard value.
Precision is the extent to which a given set of measurements agree with their mean.
UNITS OF MEASUREMENT
1. Linear, Area, and Volume Measurements
2. Angular Measurements

Radian – SI unit for plane angles (the angle subtended by an arc of a circle having a
length equal to the radius of a circle)
c) Sexagesimal Units - the degree, minute, second
d) Centesimal Units - uses grads (360° = 400 grads)
- the grad is divided into 100 centesimal minutes and the minute is
divided into 100 centesimal seconds