CE 31: SURVEYING
CHAPTER 5
Traverse Survey
Traverse Survey
A type of survey in which a number
of connected survey lines form the
framework and the directions and lengths of
the survey lines are measured with the help
of an angle measuring instrument and tape
or chain respectively
Types of traverse
Open traverse Theoretical Sum of Angles
- Series of connected lines that
have different starting and ∑ ∠ 𝑖𝑛𝑡 = (𝑛 − 2) × 180°
ending locations/points
- Suitable for surveying narrow
strips of land 𝐸𝑟𝑟𝑜𝑟 = ∑ ∠ 𝑖𝑛𝑡 − ∑ 𝑎𝑛𝑔𝑙𝑒𝑠
Closed traverse
- Series of connected lines that
Deflection Angle Traverse
have the same starting and - A horizontal angle measured
ending locations/points. clockwise or counterclockwise
- Suitable for surveying designated as right (R) or left
boundaries (L), from the prolongation of the
preceding line to the succeeding
Traversing and Traverse line.
Computations
Interior Angle Traverse
- These are angles formed
between adjacent sides within
an area, measured usually in
clockwise direction.
Error of Closure for Closed Traverse
𝐸𝑟𝑟𝑜𝑟 = 360 − ∑ 𝐷𝑒𝑓𝑙𝑒𝑐𝑡𝑖𝑜𝑛
Angle to the right Traverse
- Measured clockwise from the
backsight of the back line to a
forward line. These angles may
lie anywhere between 0° and
360°.
- For closed traverse the sum of
angles to the right is (n+2) x 180
in clockwise direction,
CE 31: SURVEYING
otherwise (n-2) x 180 if on is considered minus.
counterclockwise direction.
𝑑𝑒𝑝 = 𝑑 sin 𝑎
Linear Error of Closure (LEC)
usually, a short line of unknown
length and direction connecting the initial
and final stations of the traverse. This
quantity reflects the algebraic sum of all
accumulated errors of angle and distance
measurements.
𝐿𝐸𝐶 = √𝐶𝐿 2 + 𝐶𝐷 2
Azimuth Traverse −𝐶𝐷
- Measured clockwise either from 𝜃 = tan−1
the north or south. In a closed −𝐶𝐿
azimuth traverse, the angular
LEC – Linear Error of Closure
error is determined by noting the
difference between initial and 𝐶𝐿 – Cor. in latitude or sum of all lat.
final azimuth readings taken 𝐶𝐷 – Cor. in departure or sum of all dep.
along the first line of the 𝜃 – Bearing angle of the side of error
traverse.
𝐿𝐸𝐶
- 𝑅𝑃 =
𝐷
𝑅𝑃 – Relative Precision
𝐷 – Total Length or perimeter of
traverse
Balancing Traverse
Balancing Traverse
Computation and Adjustment of Used to describe the application of
traverse corrections to latitudes and departures
Latitude Compass rule
The north/south rectangular - Also known as the Bowditch’’ s
component of a line, and to differentiate Rulle, based on the assumption
direction, north is considered plus, and that all lengths were measured
south is considered minus. with equal care and all angles
taken with approximately the
𝑙𝑎𝑡 = 𝑑 cos 𝑎 same precision.
Departure
The east/west rectangular
component of a line, and to differentiate
direction, east is considered plus, and west
CE 31: SURVEYING
Correction to latitude of any line
𝐿𝑒𝑛𝑔𝑡ℎ 𝑜𝑓 𝑙𝑖𝑛𝑒
𝐶𝑜𝑟. = × 𝑙𝑎𝑡 𝑒𝑟𝑟𝑜𝑟
𝑡𝑟𝑎𝑣𝑒𝑟𝑠𝑒 𝑝𝑒𝑟𝑖𝑚𝑒𝑡𝑒𝑟
Correction to departure of any line
𝐿𝑒𝑛𝑔𝑡ℎ 𝑜𝑓 𝑡ℎ𝑎𝑡 𝑙𝑖𝑛𝑒
𝐶𝑜𝑟. = × 𝑑𝑒𝑝 𝑒𝑟𝑟𝑜𝑟
𝑡𝑟𝑎𝑣𝑒𝑟𝑠𝑒 𝑝𝑒𝑟𝑖𝑚𝑒𝑡𝑒𝑟
Transit Rule
- Used to balance a traverse in
which the angular
measurements are more precise
than the linear measurements.
(theodolite traversing)
Correction to latitude of any line
𝐿𝑎𝑡𝑖𝑡𝑢𝑑𝑒 𝑜𝑓 𝑙𝑖𝑛𝑒
𝐶𝑜𝑟. = × 𝑙𝑎𝑡 𝑒𝑟𝑟𝑜𝑟
𝑠𝑢𝑚 𝑜𝑓 𝑙𝑎𝑡𝑖𝑡𝑢𝑑𝑒𝑠
Correction to departure of any line
𝐷𝑒𝑝𝑎𝑟𝑡𝑢𝑟𝑒 𝑜𝑓 𝑙𝑖𝑛𝑒
𝐶𝑜𝑟. = × 𝑑𝑒𝑝 𝑒𝑟𝑟𝑜𝑟
𝑠𝑢𝑚 𝑜𝑓 𝑑𝑒𝑝𝑡𝑎𝑢𝑟𝑒𝑠
