Unit 5

Unit-5
Engineering surveys
D.PARTHIBAN-AP/CIVIL

Engineering Survey
The survey which is conducted for
determining quantities and for collecting data for
the designing of engineering works such as
roads, railways, etc., is known as Engineering.
Engineering survey has following types:
Reconnaissance Surveying
Preliminary Survey
Final Location Survey

Reconnaissance Surveying
 A reconnaissance survey provides data that enables design
engineers to study the advantages and disadvantages of a variety of
routes and then to determine which routes are feasible.
 In reconnaissance, studying existing maps is as important as the
actual field work.
 Data collected from reconnaissance survey is used for feasibility
study of all different routes, preparation of approximate estimates
of quantities and costs.
 This helps in selection of most suitable alternatives.
 This survey also helps in determining any deviations required in
the basic geometric standards to be adopted for the highway
facility.
 Reconnaissance survey is generally not required for the work
consisting of improvements to existing roads unless bypass roads
are involved.

Reconnaissance Survey Methods:
The reconnaissance survey methods may be conducted in
the following sequence:
 a) Study of topographical survey sheets, agricultural, soil,
geological and meteorological maps and aerial
photography.
 b) Aerial photography wherever necessary and feasible,
and
 c) Ground reconnaissance including another round of
serial reconnaissance for inaccessible and difficult
stretches, where required.

Study of Survey Sheets and Maps
 Reconnaissancesurvey starts with a study of the all available maps.
After study of the topographicalfeatures on the maps, a number of
economical alignments feasible in a general way are selected keeping in view
the following points:
 (i) The alignment to take into account all the controlpointsand to be
shortenedand more economical compatiblewith requirementsof gradients
and curvature.
 (ii) Shape of the alignment.
 (iii) Avoidance as far as possible of marshy ground, steep terrains, unstable
hill features and areas subject to severe climatic conditions, flooding and
inundation.
 (iv) Need of connectingimportant villages and towns.
 (v) Bridging problems, and
 (vi) Need to preserve environment and maintain ecological balance

Aerial Reconnaissance Survey
• An aerial reconnaissance will provide
a bird’s eye view of the alignments
under consideration along with the
surrounding area.
• It will help to identify factors which
call for rejection or modification of
any of the alignments.
• Final decision about the alignments to
be studied in detail on the ground
could be taken on the basis of the
aerial reconnaissance.
• https://www.youtube.com/watch?v=d
Ys4Ed1kPic
• https://www.youtube.com/watch?v=J
FLFqblGf3g

Ground Reconnaissance Survey
 Ground reconnaissance consists of
general examination of ground by
walking or riding along the probable
routes and collecting all available
information necessary for evaluating
the same.
 In the case of hill sections, it may be
advantageous sometime to start the
reconnaissance from an obligatory
point situated close to the top.
 If an area is inaccessible for the
purpose of ground reconnaissance,
aerial method should be used to clear
the doubts.
 Instruments generally used for
ground reconnaissance include
compass, Abney level / alti-meter,
pedometer, aneroid barometer,
clinometers, ghat tracer etc. Walkie-
talkie sets are useful for
communication, particularly in
difficult terrain.

Reconnaissance Survey Reports:
 Based on information collected during the reconnaissance
survey, a report should be prepared.
 The report should include all relevant information collected
during the survey and a plan to the scale of 1:50000 showing
the alternative alignments studied along with their general
profile and rough cost estimate.
 It should also discuss the merits and demerits of the different
alternatives to help the selection of one or more alignments for
detailed survey and investigation.

Preliminary Survey in Civil
Engineering
• “To collect adequate data to prepare plan/map of the
area to be used for planning and design.”
• The preliminary survey is a detailed study of a route
tentatively selected on the basis of reconnaissance
survey information and recommendations.
• It runs a traverse along a proposed route, establishes
levels, records topography, and plots results
• It also determines the final location from this plot or
preliminary map.
• The size and scope of the project will map.

Location Survey in Civil Engineering
Location is essentiallyfixing of the details of the projected highway.
It serves the dual purposeof
 Permanently establishing the center-line.
 Collecting information necessary for preparation of plans for
construction.
 The line should be established as closely as is practical to the line
drawn on the preliminary map.
 It should conform the major and minor control points and the alignment
that was previously determined.
 Staking out on the ground of the center line of the projected road
provides opportunity for minor correction like small shift of the line.
 It is useful to make a new profile and accurate cross-section from which
excavation and embankment quantities can be measured.
 Sufficient points of curvature and tangency, BMs at relatively close
interval and in position free from disturbance by construction activities.

 Direction of all property lines, distance to property corners and location of
building, fences and other improvements.
 It is important to keep notes on alignment and levels (i.e. notes taken in field
during the final location survey usually becomes part of permanent record)
 The final location survey is complete when all necessary information in
available and ready for designer to use.
 It in insured that all information required preparation of complete construction.
All information pertaining to Alignment
 Topography
 Bench mark levels
 Cross sections
 Section corner ties and other land ties
 Drainage and utilities

Setting Out Survey
 The method of setting out is the reverse of surveying
process.
 In order to begin excavation of trenches required for a
building's foundation, the builder must know the positions
and levels of building lines shown on the construction
plans on the ground.
 That is, the exact length, width, depth, and position of the
foundation trenches must be marked on the ground.
 This movement from the construction plan to the actual
site by transferring dimensions from the layout plan to the
ground is called setting out. It is probably the most
critical step in the entire construction process.

Methods of Setting Out Survey
 Setting out buildings by coordinates
 Setting out with theodolite and level
 Checking verticality
 Setting out and alignment in steel framed buildings
 Alignment and verticality in form work
 Control and calculation for route surveying

Setting out Survey works also include
• Computations and setting out Methods for:
Simple Circular Curves
Compound Curves
Reverse curves
Transition curves
Vertical curves

Horizontal control & its methods
• The horizontal control consists of reference marks of known
plan position, from which salient points of designed structures
may be set out. For large structures primary and secondary
control points are used.
• The primary control points are triangulation stations.
• The secondary control points are reference to the primary
control stations.

Reference Grid
 Reference grids are used for accurate setting out of works
of large magnitude.
 The following types of reference grids are used:
 1. Survey Grid
 2. Site Grid
 3. Structural Grid
 4. Secondary Grid

 Survey grid is one which is drawn on a survey plan, from the
original traverse.
 Original traverse stations form the control points of the grid.
 The site grid used by the designer is the one with the help of which
actual setting out is done.
 As far as possible the site grid should be actually the survey grid.
 All the design points are related in terms of site grid coordinates.
 The structural grid is used when the structural components of the
building are large in numbers and are so positioned that these
components cannot be set out from the site grid with sufficient
accuracy.
 The structural grid is set out from the site grid points.
 The secondary grid is established inside the structure, to establish
internal details of the building, which are otherwise not visible
directly from the structural grid.D.PARTHIBAN-AP/CIVIL

Vertical Control & its Methods
• The vertical control consists of establishment of
reference marks of known height relative to some
special datum.
• All levels at the site are normally reduced to the near
by bench mark, usually known as master bench mark.
• The setting of points in the vertical direction is
usually done with the help of following rods:
 1. Boning rods and travelers
2. Sight Rails
3. Slope rails or batter boards
 4. Profile boards

Boning rods
• A boning rod consist of an
upright pole having a horizontal
board at its top, forming a ‘T
‘shaped rod.
• Boning rods are made in set of
three, and many consist of three
‘T’ shaped rods, each of equal
size and shape, or two rods
identical to each other and a
third one consisting of longer
rod with a detachable or
movable ‘T’ piece.
• The third one is called traveling
rod or traveler.

Sight Rails
• A sight rail consist of horizontal cross
piece nailed to a single upright or pair
of uprights driven into the ground.
• The upper edge of the cross piece is
set to a convenient height above the
required plane of the structure, and
should be above the ground to enable
a man to conveniently align his eyes
with the upper edge.
• A stepped sight rail or double sight
rail is used in highly undulating or
falling ground.

Slope rails or Batter boards
• These are used for controlling
the side slopes in
embankment and in cuttings.
• These consist of two vertical
poles with a sloping board
nailed near their top.
• The slope rails define a plane
parallel to the proposed slope
of the embankment, but at
suitable vertical distance
above it.
• Travelers are used to control
the slope during filling
operation.

Profile boards
• These are similar to sight rails, but are used to define the corners, or
sides of a building.
• A profile board is erected near each corner peg.
• Each unit of profile board consists of two verticals, one horizontal
board and two cross boards.
• Nails or saw cuts are placed at the top of the profile boards to
define the width of foundation and the line of the outside of the
wall

CURVE
 A curve is nothing but an arc which
connects two straight lines which are
separated by some angle called
deflection angle.
 This situation occurs where the
alignment of a road way or rail way
changes its direction because of
unavoidable objects or conditions.
 The object may be a hill or a lake or a
temple etc. so, for the ease of
movement of vehicle at this point a
curve is provided.

HORIZONTAL CURVES

Simple Circular Curve
• Simple circular curve is normal horizontal
curve which connect two straight lines with
constant radius.

COMPONENTS OF SIMPLE CURVE

Compound Curve
• Compound curve is a combination of two or
more simple circular curves with different
radii.
• In this case both or all the curves lie on the
same side of the common tangent.

Reverse Curve
• Reverse curve is formed when two simple circular
curves bending in opposite directions are meet at a
point. This points is called as point of reverse
curvature. The center of both the curves lie on the
opposite sides of the common tangent. The radii of
both the curves may be same or different.

Transition Curve
• A curve of variable radius is termed as
transition curve.
• It is generally provided on the sides of
circular curve or between the tangent and
circular curve and between two curves of
compoundcurve or reverse curve etc.
• Its radius varies from infinity to the
radius of provided for the circular curve.
• Transition curve helps gradual
introduction of centrifugal force by
gradual super elevation which provides
comfort for the passengers in the vehicle
without sudden jerking.

Spiral Curve
• Spiral is a type of transition curve
which is recommended by IRC as
ideal transition curve because of its
smooth introduction of centrifugal
acceleration.
• It is also known as clothoid.

Lemniscate
• Lemniscate is a type of transition
curve which is used when the
deflection angle is very large.
• In lemniscate the radius of curve is
more if the length of chord is less.

Vertical Curves
• The curves provided in vertical plane of earth is called as
vertical curve.
• This type of curves are provided when the ground is non-
uniform or contains different levels at different points.
• In general parabolic curve is preferred as vertical curve in
the vertical alignment of roadway for the ease of
movement of vehicles.
• But based on the convexity of curve vertical curves are
divided into two types
 Valley curve
 Summit curve

Valley Curve
• Valley curve connects falling gradient with
rising gradient so, in this case convexity of
curve is generally downwards.
• It is also called as sag curve.

Summit Curve
• Summit curve connects rising gradient with falling
gradient hence, the curve has its convexity upwards.
• It is also called as crest curve.

SETTING OUT FOUNDATION TRENCHESOF BUILDING.
• Before Commencement, of the excavation of trenches
for foundation, a setting out plan is prepared on paper.
• The setting out plan is a dimensioned ground floor plan,
usually drawn to scale of 1:50.
• The plan is fully dimensioned at all breaks and openings.
• One of the methods of setting out of foundations is to
first mark the centre line of the longest outer wall of
building by stretching a string between wooden pegs
driven at its ends.
• This serves as the reference line for marking the centre
line of all the walls of the building.
• The centre line of the wall, which is perpendicular to the
long wall, is marked by setting up a right angle.
• Right angle is set up by forming triangles with sides
3,4and5units long.

https://www.youtube.com/watch?v=h
3UQQD3VOs4

• If we fix the two sides of the right angles triangle
to be 3 m, and 4 m, then the third side i.e. the
hypotenuse should be taken a 5 m.
• The dimensions should be set out with a steel
tape.
• The alternative method of setting out right angle
is by the use of theodolite.
• This instrument is also helpful in setting out acute
or obtuse angles.
• Small right-angled Projections are usually set out
with mason’s square.

 The method of Setting out of Foundations described above is
not so reliable for important works as there is likelihood of the
wooden pegs being pulled up or displaced.
 In an accurate method, the centre lines of the building walls arc
carefully laid by means of small nails fixed into the head of the
wooden pegs driven at the quoins.
 In case of rectangular buildings, the diagonal from the opposite
corners are checked for their equality.
 Small brick walls, pillars or platforms are constructed 9ocm clear of
the proposed foundation trench.
 The platforms are about 15 cm wider than the trench width and are
plastered at top. The tops of all platforms or pillars should be at the
same level preferably at plinth or floor level of building.
 The strings are then strenched over the nails in the pegs and the
corresponding lines are marked on the wet plastered platforms top
by pressing the stretched string on the plastered surface by a trowel.
 The outside lines of the foundation trench and the plinth lines are
marked on the wet plastered platform top in the similar manner.

• Before starting excavation, the strings are stretched between
the outside lines of the foundation trench marked over the
platform top and the cutting lines are marked on the ground by
lime powder.
• If necessary, the lines may be marked by a daghbel or pick-
axe.

Mine(or) Underground (or) Tunnel Surveying
• Underground surveying embraces the survey operations performed beneath
the surface of the earth in connection with tunneling, exploration and
constructionin subterraneanpassageways.
• It is quite different from surveying on the surface.

The following peculiarities of underground surveys
indicate how they differ from surface surveys
 Artificial illumination is required to view instrument
crosshairs, to read verniers, to sight targets etc. Because of
poor lighting.
 Working space in passageways is often cramped.
 Instrument stations and benchmarks for levelling must often
be set into the roof of a passageway to minimize
disturbance from the operations being carried on in the
workings.
 Instrument stations are set with some difficulty since plugs
must be driven into drill holes in rock.
 In many instances the underground workings arc wet, with
considerable water dripping from the roofs of passage ways
and running along the floors.

Applications of Underground Surveys
The major application of underground surveys is in the
construction of tunnels and other underground utilities.
The tunnel is constructed when open excavation becomes
uneconomical usually when it is more than 20 m. It
 Reduces the grade
 Shortens the distance between given points separated by a
dividing mountain or ridge.
 Meets the demand of-modern rapid transit in a city.
 Engineering operations to be performed
 Exact alignment
 Proper gradient
 Establishment of permanent stations marking the proposed
route.

Methods and Procedure of Tunnel Surveying
• 1. The initial procedure is to carry out a preliminary survey that is later
made more precise by surveying the line on the surface of the area under
consideration
• 2. From the start of the excavation, as a part of tunnel construction, it is
essential to keep up even minute accuracy with the center line that is
already marked.
• When a new area of excavation is commenced, the center line of the
before finished work has to be carried forward over the new face.
• No shifting of the center line in vertical or horizontal direction is accepted,
when the opposite faces meet with adjacent headings.
• 3. Ordinary engineers transit and properly handled works give satisfactory
results for the construction of short tunnels.
• 4. Tunnel transit that is large and sophisticated, is fitted to a striding level,
that helps in keeping the transverse axis horizontal. This is necessary for
long tunnel construction.
• 5. The instruments above mentioned should undergo periodic
maintenance, calibration as well as checking.D.PARTHIBAN-AP/CIVIL

• 6. The procedure of leveling is carried out in a
normal way. But areas with steep slopes are
measured with utmost care.
• This is ensured by having equal values for
backsight and foresight.
• This would reduce the errors that are caused
by the human, like improper or mal -
adjustments of the instruments.
• 7. There are two methods that can be
employed to measure the horizontal distances.
• They are stepping and inclined sights. Any of
these methods can be employed based on the
area under consideration and convenience.
• The steel tapes used for the measurement are
checked for errors due to any cause of tension
or temperature changes. This would result in
cumulative errors in the measures.
• The below figure shows the alignment of a
curve line, based on which the construction
must be proceeded
Alignment of Curve Line
in Tunnel Surveying

• The center line of the curve in the figure
is the alignment through which the
center line of the tunnel must proceed.
• This is the curve that must be
determined.
• The headings consist of short tangents
that are drawn to the curved lines as ab,
bc, cd etc.
• To locate the center line of the area,
offsets from the above-mentioned
tangents are set off.
• When the heading has proceeded up to
x y, point like ‘n’ on the tangents is
aligned as shown in the figure.
• We then set off the calculated offset, i.e.
n-o that will intersect the center line of
the heading.
• After each blasting of the heading face,
the center line recommended being
transferred. Alignment of Curve Line
in Tunnel Surveying

Decision of Shape and Size of the Tunnel
• The shape of the tunnel is decided based on the nature and the type of the soil or the ground
that is penetrated during the surveying and the excavation procedure.
• After surveying and related construction works,a choice of shape can be made.
• The size of the tunnel is already measured in the design, as it is based on the scope or
requirement of the project.
• Among different cross sections, the circular cross sections are found to be the best shape to
bring huge resistance towards the internal and external pressures.
• This also has another peculiarity of bringing larger size for a smaller diameter
• . But in engineers point of view, they demand high lining and covering to protect it from
high vibration in railway uses.
• So, an optimized shape is a tunnel with circular top and vertical side walls Another shape is
the horseshoe type.
• They are compromised with the problems related to the circular tunnel shape.

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