before going to viva you should know these points:
General principles of surveying are
Working from whole to part: In this principle the whole area is first framed out
by main stations and survey lines. Then the area is divided into no. of wellconditioned
triangles and linear measurements are done which prevents in error
Location of new control point by measurements from two control points: From
fixed reference points new stations are fixed from at least two measurements.
Measurements may be linear or angular (by chain, tape, theodolite, compass).
In a survey camp a single group has to conduct a detailed survey for
Preparation of a topographic map of the given area
Selection of a suitable Road alignment
Selection of a suitable Bridge site
The general objectives of the survey camp are listed below-
To become familiar with the surveying problems those are likely to arise during
the field works.
To develop confidence in actual field surveying.
To become familiar with different instruments, their functions and handling for
their use in surveying.
To become familiar with the spirit and importance of teamwork, as surveying
cannot be carried out by a single person.
To complete the task or the project within the given time limit.
To collect the required field data in a systematic way.
To compute and manipulate the observed data in the required accuracy and
present it in theoretical, tabular and diagrammatical forms that it is easily
understood by other engineering professionals.
SCOPE OF WORK FOR SURVEY CAMP
Topographic Map Presentation
Area Coverage:1.5 to 2.0 hectares
Scale for the Plot of Major Traverse: 1:1000
Scale for the Plot of Minor Traverse: 1:500
Scale for Plot of Topographic Map: 1:500
Contour Interval:1 m (depending upon the site relief)
Control Points Establishment
• At least 25-35 stations (Main control stations)
• Two sets of Horizontal Angle, One set of Vertical Angle
• Distance measurement by three-way taping and by EDM (1:2000 accuracy)
• Vertical control by Leveling, check by trigonometric leveling
• Fly Leveling, at least 0.5 – 1.0 km (± 25√K mm accuracy)
• Leg ratio: Major Traverse 1:2, Minor Traverse 1:3
Road Alignment Survey
•At least 500 m to 700m or more stretch
•Scale for Plan: 1:1000
•Scale for Longitudinal section: V – 1:100 & H – 1:1000
• Cross section: 20 m interval, scale same for V & H – 1: 100
•Left right observation: 10 m minimum on either side of proposed center line
• Horizontal curve by both linear and angular method
• Vertical curve setting with gradient (7 to 12) %
Bridge Site Survey
• up-stream details at least 120 m, Downstream details at least 40 m
• Scale for plotting minimum area of observation of coverage plan 1:500
• Contour interval: 2.0 m or depending upon the site relief
• Longitudinal section: H=1:200,V=1:100
• Cross section: (10 to 20) m interval (depending upon the site relief), scale
NORMS (TECHNICAL SPECIFICATIONS)
points which should be kept in mind for appropriate selection of major
traverse control points forming the closed traverse around the premises of the area to
be surveyed are summed up as follows:
points needed to be
kept in the mind while fixing major traverse stations are as follows:
Measurement of traverse angles
Bearing computation of the traverse legs
In a closed traverse, the algebraic sum of the latitudes and departures must be zero if
linear as well as angular measurements of the traverse along with their computations
are correct. If not, the distance between the starting station & point or position of the
same station obtained by the calculation is known as closing error.
Plotting of major traverse stations
Adjustment of level
i. Temporary adjustment of level
ii. Permanent adjustment of level
a. HI Method
b. Rise and Fall Method
steps followed while
carrying out the detail survey are summed up as follows:
Characteristics of Contours
Interpolation of the Contour lines
By Arithmetic Calculations
By Graphical Method
BRIDGE SITE SURVEY
NORMS (TECHNICAL SPECIFICATIONS)
The following things were considered while selecting a bridge site:
Deflection angle (Δ) = (360° or 180°) – Observed angle.
Simple Circular Curve
Length of tangent: R tan (Δ/2)Where, R = radius of simple circular curve Δ = deflection angleLength of long chord: 2R sin(Δ/2)Apex distance: R (sec(Δ/2) – 1)Mid ordinate: R (1 – cos(Δ/2))Length of curve: πRΔ 180°Chainage of T1: Chainage of IP – R tan (Δ/2)Chainage of T2: Chainage of T1 + πRΔ 180°