Unit - 1

Introduction

1.1 Importance of Surveying

Surveying is the art of determining the relative positions of different objects on the surface of the earth.

Importance of Surveying:

• The making plans and layout of all Civil Engineering initiatives inclusive of creation of highways, bridges, tunnels, dams and many others are primarily based totally upon surveying measurements.
• Moreover, for the duration of execution, challenge of any importance is built alongside the strains and factors set up with the aid of using surveying.
• Thus, surveying is a simple requirement for all Civil Engineering initiatives.
• Other major works wherein surveying is frequently utilised are:

1. To repair the countrywide and kingdom boundaries;
2. To chart coastlines, navigable streams and lakes;
3. To set up manage factors;
4. To execute hydrographical and oceanographic charting and mapping; and
5. To put together topographic map of land floor of the earth.

Key Takeaways:

Surveying is the art of determining the relative positions of different objects on the surface of the earth.

2.2 Types of Surveying

There are two types of surveying:

1. Plane surveying
2. Geodetic surveying

Plane Surveying:

1. The curvature of the earth is not taken into consideration.
2. It is carried out for small area.
3. Plane surveying is conducted by state agencies.
4. It is carried out over an area less than 250 km².

Geodetic surveying:

1. The curvature of the earth is taken into consideration.
2. It is carried out for large area.
3. Geodetic surveying conducted by survey of India Department.
4. It is carried out over an area greater than 250 km².

Key Takeaways:

There are two types of surveying:

1. Plane Surveying
2. Geodetic surveying

3.3 Principle

The two-fundamental principle upon which various methods of plane surveying falls are:

Location of a point by measurement from two points of reference

The relative position of a point to be surveyed is located by measurement from at least two points of reference, the positions of which have already been fixed.

If P and Q are the two reference points on the ground, any other point, such as R, can be found by any of the direct methods. A single method is sufficient to locate the relative position of ‘R’ with respect to reference points P and Q, it is necessary to adopt at least any two methods to fix the position of point ‘R’.

Working from whole to part

Here it is always desirable to carryout survey work from whole to part which means, when an area is to be surveyed then first a system of control points is to be established covering the whole area with very high precision. Then small details are located by less accurate methods.

The idea of working this way is to prevent the accumulation of errors and to control and localize minor errors which would expand to greater magnitudes if the reverse process is followed, thus making the work uncontrolled at the last.

Key takeaways:

Here it is always desirable to carryout survey work from whole to part which means, when an area is to be surveyed then first a system of control points is to be established covering the whole area with very high precision. Then small details are located by less accurate methods.

1.4 Scales

Concept of Scale:

The ratio by which actual length of the object is reduced or increased is known as scale.

Types of scale:

1. Full size scale
2. Reducing scale
3. Increasing or Enlarging scale

1. Full size scale:

• If the actual length of the object is shown on the drawing.

2. Reducing scale:

• If the actual length of the object is reduced in order to accommodate it on the drawing sheet the scale is said to be a reducing scale.

3. Increasing or Enlarging scale:

• If the actual length of an object is enlarged so as to bring out its details more clearly on the drawing, the scale used is said to be increasing scale.

Key Takeaways:

There are three types of scale:

1. Full size scale
2. Reducing scale
3. Increasing or Enlarging scale

1.5 Plan and Maps

The following phrases are usually utilized in surveying:

(i)                Plan: A plan is the graphical illustration of the capabilities on this planet floor or under the earth floor as projected on a horizontal plane. On a plan or a map most effective horizontal distances are shown. The plan or map is made in keeping with a few scale chosen.

(ii)              Map: The illustration of earth floor on small scale is known as map.  The essential Object of the survey is to broaden a plan and a map. The consequences of surveys whilst drawn on paper paperwork a plan or a map

Key takeaways:

A plan is the graphical illustration of the capabilities on this planet floor or under the earth floor as projected on a horizontal plane

1.6 Shrinkage of Maps

The made from the shrinkage issue and unique scale is referred to as gotten smaller scale. If a graphical scale isn't drawn at the plan and the sheet on which the plan is drawn shrinks because of versions in atmospheric conditions, it turns into crucial to locate the gotten smaller scale of the plan.

The distance among any acknowledged factors at the plan may be as compared with the real distance among the 2 factors. The shrinkage ratio or shrinkage thing is then same to the ratio of the shriveled duration to the real duration. Shrinkage Factor = Shrunk duration / Actual duration

Key takeaways:

If a graphical scale isn't drawn at the plan and the sheet on which the plan is drawn shrinks because of versions in atmospheric conditions, it turns into crucial to locate the gotten smaller scale of the plan.

1.7 Mapping Concepts

Determine mapping accuracy through evaluating the mapped place of decided on well-described points to their “true” place as decided through a technique recognized to supply extra correct results (e.g., traditional discipline survey to test photogrammetric).

Mapping accuracy requirements classify a map as assembly a sure statistical stage of accuracy. Horizontal (or plan metric) map accuracy is commonly expressed in phrases of two-dimensional radial positional mistakes measures (i.e., the basis mean square (RMS) statistic) and is often associated with plotting scale. Vertical map accuracy is expressed in phrases of one-dimensional RMS elevation errors, and is often associated with contour c program language period. Maps, surveys and associated geospatial information which are examined and observed to conform with a exact widespread shall have a certification declaration that sincerely shows the goal map scale and contour c program language period of the information layer. Project documentation will encompass trying out techniques and statistical precise of the accuracy assessment. Horizontal and vertical accuracy type of functions is mentioned on the ninety five percentage self assurance stage through changing RMS mistake information

Horizontal (two-dimensional) ninety five% self assurance = RMS mistakes * 1.7308 Equation Vertical (one-dimensional) ninety five% self assurance = RMS mistakes * 1.9600 Equation Project specs will specify the geographic quantity of information to be examined and the quantity of trying out (if any) to be conducted. Due to the excessive price of trying out and the various packages for mapping information, now no longer all map merchandise ought to be examined. In those cases, the declaration shall indicate that the mapping techniques had been designed and carried out beneath situations recognized to fulfill a sure stage of accuracy, however that the accuracy type is expected. An expected accuracy declaration is mainly relevant to CADD and GIS databases that can be compiled from a form of re assets containing recognized or unknown accuracy reliability.

Mapping accuracy requirements are related to the very last improvement of each the goal horizontal plotting scale and contour c program language period. Photogrammetric flying top and floor survey density necessities are exact primarily based totally upon the layout goal scale and contour c program language period. The use of Computer Aided Drafting and Design (CADD) and/or Geographic Information Systems (GIS) lets in plani metric functions and topographic elevations to be conveniently separated onto various layers and depicted at any scale or contour c program language period. Therefore, it's far crucial that those spatial information layers comprise descriptor statistics figuring out the authentic supply and mapping accuracy type.

The FLH widespread for topographic mapping is the FGDC National Standard for Spatial Data Accuracy (NSSDA) and the ASPRS Accuracy Standards for Large-Scale Maps. This widespread became developed, and stays commonly recognized, through the photogrammetric industry. The ASPRS accuracy requirements and statistical trying out standards also can be used to reality and classify topographic mapping compiled through different methods (e.g., terrestrial discipline survey, LiDAR). Exhibit 5.3–D depicts endorsed scales, contour periods and related positional tolerances for FLH mapping projects. Functional sports are commonly divided into layout and Surveying and Mapping May 2018 Survey Planning 5-15 production tasks, and planning-stage tasks. For maximum projects, identity of the kind of project is the most effective layout assumption required.

Key takeaways:

Therefore, it's far crucial that those spatial information layers comprise descriptor statistics figuring out the authentic supply and mapping accuracy type.

1.8 Map Projections

A map projection is one in all many techniques used to symbolize the third-dimensional floor of the earth or different spherical frame on a 2-dimensional aircraft in cartography (mapmaking). This manner is typically, however now no longer necessarily, a mathematical procedure (a few techniques are graphically based)

Creation of a Map Projection

The advent of a map projection entails 3 steps wherein facts is misplaced in every step: choice of a version for the form of the earth or spherical body (selecting among a sphere or ellipsoid) rework geographic coordinates (longitude and latitude) to aircraft coordinates (easting’s and nothings).

Lessen the scale (in guide cartography this step got here second, in virtual cartography it comes last) Metric residences of maps anticipate that the viewer has an orthogonal view of the map (they're searching instantly down on each point). This is likewise referred to as a perpendicular view or everyday view. The metric residences or a map are

Area shape direction distance scale Choosing a projection floor If a floor may be converted onto any other floor with out stretching, tearing, or shrinking, then the floor is stated to be an relevant floor. The sphere or ellipsoid aren't relevant with a aircraft floor so any projection that tries to venture them on a flat sheet will need to distort the image (just like the impossibility of creating a flat sheet from an orange peel). A floor that may be spread out or unrolled right into a flat aircraft or sheet without stretching, tearing or shrinking is known as a ‘developable floor’.

The cylinder, cone and of direction the aircraft are all developable surfaces due to the fact that they may be spread out right into a flat sheet without distorting the projected image (even though the authentic projection of the earth’s floor at the cylinder or cone might be distorted).

Orientation of the projection

Once a desire is made among the usage of a cylinder or cone is made, the orientation for that form ought to be chosen (how the cylinder or cone is “placed” at the earth). The orientation of the projection floor may be normal (inline with the earth’s axis), transverse (at proper angles to the earth’s axis) or oblique (any attitude in among). These surfaces will also be both tangent or secant to the sector or ellipsoid (in case you see each a 1st and 2d parallel on a projected map then the projection ought to be secant).

Key takeaways:

A map projection is one in all many techniques used to symbolize the third-dimensional floor of the earth or different spherical frame on a 2-dimensional aircraft in cartography (mapmaking). This manner is typically, however now no longer necessarily, a mathematical procedure (a few techniques are graphically based)

1.9 Total Station uses and application

A total station is an electronic/optical instrument used in modern surveying and building construction that uses electronic transit theodolite in conjunction with electronic distance meter (EDM). It is also integrated with microprocessor, electronic data collector and storage system.

The instrument is used to measure sloping distance of object to the instrument, horizontal angles and vertical angles. This Microprocessor unit enables for computation of data collected to further calculate the horizontal distance, coordinates of a point and reduced level of point.

Data collected from total station can be downloaded into computer/laptops for further processing of information.

Total stations are mainly used by land surveyors and civil engineers, either to record features as in topographic surveying or to set oust features (such as roads, houses or boundaries). They are also used by archaeologists to record excavations and by police, crime scene investigators, private accident Reconstructions and insurance companies to take measurements of scenes.

• Missing line measurement (MLM}
• Control Survey (Traverse).
• Archaeologists use total station to record excavations and its details
• Height measurement (Remove elevation measurement- REM).
• Resection are easy by total station.
• Remote Distance Measurement (RDM)
• General purpose of angle and distance measurement
• Detailed maps

Uses of Total Station: -

Total Station are use in following areas: -

• Road Survey
• Rail Survey
• Canal Survey
• Mine Survey
• Engineering Survey
• Large Scale Survey

Advantages and Applications of Using Total Stations

Advantages:

• Field work is very fast as compared to conventional survey.
• Calculation is also fast and accurate.
• Accuracy is very high.
• Manual errors can be eliminated.
• Computers can used for map making and contour and its cross-sections

Applications:

The following application of total station are as given below: -

• Detail survey is carried out easily by this technique.
• Missing Line Measurement (MLM)
• Plotting of contours
• Carrying out controlled surveys
• Used to fix the missing pillars and column.
• Area calculations

Key takeaways:

A total station is an electronic/optical instrument used in modern surveying and building construction that uses electronic transit theodolite in conjunction with electronic distance meter (EDM). It is also integrated with microprocessor, electronic data collector and storage system.

1.10 Chain Surveying: Purpose

Chain surveying is the kind of surveying wherein handiest linear measurements are made within side the field. The foremost precept of chain surveying or chain triangulation is to offer a framework encompass some of well-conditioned triangles or almost equilateral triangles. It is used to locate the vicinity of the field.

Various movements and techniques are used within side the survey to degree the area. These movements and practices are primarily based totally on a few easy and easy ideas. These ideas are derived from the reports of the extraordinary surveyors.

Keeping them in thoughts whilst surveying can assist take away errors and accuracy may be maintained in surveys. The major ideas of the survey are as follows

To Work from the Whole to the Part

To Fix the Position of a New Station with the aid of using at Least Two Independent Processes

To Choose the Method of a Survey That Is the Most Suitable for the Purpose. To Record Filed Data Carefully.

Measurements of Distance via way of means of Chain Surveying: Chains and scales are usually used to immediately degree the linear distance among factors above the earth’s surface. We will observe the forms of those chains and measurements and the way the distances are measured via way of means of the number one cause of the survey is to create maps.

The maps are drawn in a horizontal plane. Therefore the gap need to additionally be measured in a horizontal plane. That is, if the floor is sloping, its equilibrium distance is discovered to be horizontally spaced and simplest then is it used to attract a map. The distance among factors within side the survey is the horizontal distance among them.

Key takeaways:

The maps are drawn in a horizontal plane. Therefore the gap need to additionally be measured in a horizontal plane.

1.11 Chaining

• A chain is prepared with 100 or 150 pieces of galvanised mild steel wire of 4mm, the end of the pieces are bent to form loop and then the pieces are connected to get with the help of 3 oval rings. Which make the chain flexible. Two brass handles are provided at the two ends of the chain. Tallies are provided at every 10 or 25 links.

1. Metric chain
2. Steel Band
3. Engineer's chain
4. Gunter's chain,
5. And Revenue chain

Metric chain:

• Metric chains are available in lengths of 20m and 30m. The 20m chain is divided into 100 links, each of 0.2m. Tallies are provided at every 10 links (2m). This chain is suitable for measuring distances along fairly level ground.

Steel Band:

• It consists of a ribbon of steel of width 16mm and of length 20 or 30m. It has a brass handle at each end. It is graduated in meters, decameters, and centimeters on one side and has 0.2m links on the other. The steel band is used in projects where more accuracy is required.

Engineer's chain:

• The engineer's chain is 100 ft long and is divided into 100 links. So, each link is of l ft. Tallies are provided at every 10 links (10 ft), the central tally being round. Such chains were previously used for all engineering work.

Gunter's chain:

• It is 66 ft long and divided into 100 links. So, each link is of 0.66. It was previously used for measuring distances in miles and furlongs.

Revenue chain:

• The revenue chain is 33 ft long and divided into 16 links. It is mainly used in cadastral survey.

Key Takeaways:

There are five types of chain:

1. Metric chain
2. Steel Band
3. Engineer's chain
4. Gunter's chain,
5. And Revenue chain

1.12 Accessories

1. Alidade
2. Alidade table
3. Cosmolab
4. Dioptra
5. Dumpy level
6. Engineer's chain
7. Geodi meter
8. Grapho meter.
9. Level
10. Level staff
11. Measuring tape
12. Plane table Pole (surveying)
13. Prism (surveying) (nook dice retroreflector)
14. Prismatic compass (perspective measurement)
15. Ramsden surveying instruments
16. Ranging rod
17. Surveyor's chain
18. Surveyor's compass
19. Tachymeter (surveying) Tape (surveying)
20. Telluro meter Theodolite
21. Half theodolite
22. Plain theodolite
23. Simple theodolite
24. Great theodolite
25. Non-transit theodolite
26. Transit theodolite
27. Seconds theodolite
28. Electronic theodolite
29. Mining theodolite
30. Suspension theodolite
31. Traveling theodolite
32. Pibal theodolite
33. Registering theodolite
34. Gyro-theodolite
35. Construction theodolite
36. Photo-theodolite
37. Robotic theodolite
38. Vernier theodolite
39. Total station Transit (surveying)
40. Tripod (surveying) Universal instrument (surveying)

1.13 Ranging and its types

Ranging Out Survey Lines

Direct Ranging:

Direct ranging is the ranging carried out whilst the intermediate factors are inter visible.

Indirect Ranging:

Indirect ranging is hired whilst the 2 factors aren't inter visible or the 2 factors are at a protracted distance.

The first step of any production paintings is surveying and as a consequence it's far an vital department of civil engineering. In general, surveying may be described because the artwork of figuring out the relative role of numerous capabilities above, on, or below the floor of the earth making use of distinctive gadgets and getting ready the maps. One of the vital components of surveying is ranging in surveying. In general, ranging may be described because the method of solving or organizing numerous intermediate factors to degree the survey line.

The status quo of fixation of such intermediate factors is completed using ranging rods or ranging poles. Generally, while the period of the survey line is longer than the period of the chain, the entire period can not be decided through chaining alone. In any such case, the intermediate factors alongside the survey line are decided through ranging.

In case, the period of the survey line is lesser than the period of the chain, the period of the road can without problems be decided however if the period of the survey line is greater, then the survey strains need to be divided into positive intermediate points, earlier than undertaking the chaining method. This method is called ranging. There are kinds of ranging in surveying this is usually followed i.e. direct ranging and oblique ranging.)

The technique of ranging in surveying may be classified into principal kinds i.e. direct ranging and oblique ranging. The styles of ranging are similarly defined below. a. Direct Ranging Direct ranging is the technique of ranging this is followed while the 2 survey stations are inter-seen i.e. the 2 endpoints of the survey line are seen. In general, direct ranging may be similarly grouped into the following:

Ranging with the aid of using Eye It is the form of technique of direct ranging this is completed in reality with the aid of using the resource of the eyes of the surveyor. As proven within side the discern below, permit A and B be the 2 inter-seen factors on the ends of the survey line.

1. Ranging through Eye It is the kind of technique of direct ranging this is performed truly through the resource of the eyes of the surveyor. As proven within side the determine below, permit A and B be the 2 inter-seen factors on the ends of the survey line. The surveyor then stands with a ranging rod at factor A regarding factor B. Then, any other man or woman takes the ranging rod and fixes or establishes an intermediate factor among the road AB. Let the intermediate factor installed be C. It have to be stated that the space of the intermediate factor isn't always more than one chain duration from the primary factor A of the survey line. The surveyor at factor A then indicators any other man or woman on the intermediate factors in order that the ranging rod is in ideal line with the endpoints A and B. Hence, the intermediate factors are determined.
2. Ranging via way of means of Line Ranger Ranging via way of means of Line Ranger is the sort of direct ranging approach wherein the intermediate factors are constant at once making use of an tool called line ranger. The line ranger is an tool that has both aircraft replicate preparations or isosceles prisms which can be positioned one over the other. The association and silvering of the diagonals of the prism are achieved such that they replicate incident rays. Let us do not forget endpoints of a survey line particularly A and B

Key takeaways:

In case, the period of the survey line is lesser than the period of the chain, the period of the road can without problems be decided however if the period of the survey line is greater, then the survey strains need to be divided into positive intermediate points, earlier than undertaking the chaining method.

1.14 Error

1 CALIBRATION OF TOTAL STATIONS

Maintaining the high level of accuracy offered by modern total stations, there is much more emphasis on monitoring instrumental errors, and some construction sites require all instruments to be checked regularly using procedures outlined in the quality manuals. 

Some instrumental errors can be eliminated by observing on two faces of the total station and averaging, but because one face measurements is the preferred method on site, it is important to determine the amount of instrumental errors and correct for them.

For total stations, instrumental errors are measured and corrected by electronic calibration procedures that are carried out at any time and are applied to the instrument on site.

Since calibration parameters can change due to mechanical shock, temperature changes and rough handling of high-precision instrument, an electronic calibration should be carried out on a total station as follows:

1. Before using the instrument for the first time
2. After long storage periods
3. After rough or long transportation
4. After long periods of work
5. Following big changes in temperature
6. Regularly for precision surveys

Before every calibration, it is essential to allow the total station enough to reach the ambient temperature.

2 HORIZONTAL COLLIMATIONS (OR LINE OF SIGHT ERROR)

This axial error happens when the line of sight is not perpendicular to the tilting axis. It affects all horizontal circle readings and increases parallel to steep sightings, but this is eliminated by observing on two faces. For single face measurements, an on-board calibration function is used to determine c, the deviation between the actual line of sight and a line perpendicular to the tilting axis. A correction will be applied automatically for this to all horizontal circle readings.

3 TILTING AXIS ERROR 

Axial errors occur when the titling axis of the total station is not perpendicular to its vertical axis, this has no effect on sightings taken when the telescope is horizontal, but produces errors into horizontal circle readings when the telescope is tilted, especially for steep sightings.

But with horizontal collimation error, this error is erased by two face measurements, or the tilting axis error (a) is measured in a calibration procedure and a correction applied for this to all horizontal circle readings.

4 COMPENSATOR INDEX ERROR

Errors that were caused by not leveling a theodolite or total station carefully cannot be eliminated by taking face left and face right readings. If the total station is fitted with a compensator, it will measure residual tilts of the instrument and will apply corrections to the horizontal and vertical angles for these.

All compensators will have a longitudinal error l and traverse error t known as zero-point errors which are averaged using face left and face right readings but for single face readings must be determined by the calibration function of the total station.

A vertical collimation error exists on a total station if the 0o to 180o line in the vertical circle does not coincide with its vertical axis and this zero-point error is present in all vertical circle readings and like the horizontal collimation error, it is eliminated by taking FL and FR readings or by determining i

Any difference between the measured horizontal and vertical angles is then identified as an instrumental error and applied to all readings. The total station is thus calibrated and the procedure is the same for all of the error type.

Key takeaways:

Maintaining the high level of accuracy offered by modern total stations, there is much more emphasis on monitoring instrumental errors, and some construction sites require all instruments to be checked regularly using procedures outlined in the quality manuals. 

1.15 Chaining on uneven ground

For comfort and to gain higher results, chaining is carried out from pinnacle of hill to the toe i.e. downhill. The follower holds the 0 quit of the chain at A at the floor and the chief with the opposite cope with of the chain and a ranging rod movements within side the ahead path at a handy distance apart.

Right here are techniques for figuring out horizontal distance on sloping floor. Direct Method Indirect Method Direct Method of Chain Surveying This technique is likewise regarded as “Stepping Method”. The horizontal distances are at once measured with the aid of using the system of stepping. Procedure A course of chain or tape is stretched out from ‘P’. The course duration of chain or tape relies upon at the steepness of the floor. The follower holds the 0 stop of the chain at ‘P’ and directs the chief at P1 to be within side the line of PQ and stretch the chain or tape above the floor in horizontal line.

He chief then transfers the factor ‘P1’ to P2 at the floor by way of plumb bob or losing a pebble or an arrow, Now the fans take the brand new function ‘P2’ and directs the chief to transport ahead and stretch the tape or chain in a line of PQ. Now the fans take the brand new function ‘P2’ and directs the chief to transport ahead and stretch the tape or chain in a line of PQ and the brand new function is P3.

Again the chief transfers the factor P3 to P4 at the floor as finished earlier. This method is repeated until the factor Q is reached. Horizontal distance PQ = S1 + S2 + S3 + S4 + S5 Indirect Method of Chain Surveying In this method, the sloping aspect is measured at the floor and later it's far transformed into the horizontal equal the usage of geometrical condition. The following techniques are followed for calculating horizontal distance indirectly: By measuring attitude of inclination By measuring distinction of levels By hypotenuse allowance

Key takeaways:

For comfort and to gain higher results, chaining is carried out from pinnacle of hill to the toe i.e. downhill. The follower holds the 0 quit of the chain at A at the floor and the chief with the opposite cope with of the chain and a ranging rod movements within side the ahead path at a handy distance apart.

1.16 Tape corrections

The chain surveying completed with the aid of using a tape is anticipated to have a few mistakes because of wrong tape measurements. In everyday chaining works, the mistakes are neglected. But for essential and specific survey works in construction, correct tape corrections are provided.

Different corrections furnished for tape measurements whilst accomplishing chain surveying are defined within side the article. The correction is nice if the inaccurate duration is to be expanded and the correction is terrible if the inaccurate duration should be decreased.

The corrections done for seven not unusual place mistakes in linear measurements via way of means of tape are: Correction for absolute length Correction for pull or tension Correction for temperature Correction for Sag Correction for Slope Correction for Alignment Reduction for the ocean level

Correction for Absolute Length If Ca is the correction for absolute duration or the real duration, then it's miles given by: Ca = Lc/l

Where, L = Measured duration of the line; c = Correction consistent with tape duration; l= exact duration of the tape or the nominal duration. Different instances are: Absolute duration > Designated duration way Measured distance is short, subsequently the correction is additive. Absolute duration < Designated duration way, Measured distance is long, subsequently the correction is subtractive.

The signal of correction Ca is similar to that of 'c'. 2. Correction for Temperature The correction for temperature Ct is given via way of means of the formula: Tm is the suggest temperature within side the subject at some stage in measurement; To is the temperature at some stage in the standardization of the tape; L = Measured period; There are instances possible: 1. The temperature of the sphere is extra than the temperature at which the tape is standardized; Tm > To. This consequences in an boom within side the tape period, making the measured period shorter. Hence the correction is additive. 2. The temperature of the sphere is lesser than the standardized temperature, i.e. Tm period decreases. This consequences in an boom the measured period than the original. Hence the correction is subtractive.

Where, P = Pull implemented at some stage in the dimension; Po= Standard Pull; Both P and Po are measured in Newtons; L = measured period; A =Area of cross-segment in cm2; E = Young’s modulus in N/cm2. Two instances are possible: 1. Pull implemented at some stage in the dimension is extra than pull at which the tape is standardized i.e. P > Po. This outcomes in a boom within side the period of tape which makes the measured period shorter. Hence the correction is additive. 2. Pull implemented at some stage in the dimension is lesser than pull at which the tape is standardized i.e. P < Po. This outcomes in a lower in period of tape which makes the measured period longer. Hence the correction is subtractive. The pull implemented within side the area should be much less than 20 instances the burden of the tape used for dimension. 4. Correction for Sag Stretching the tape among helps make the tape to shape a horizontal catenary. Hence, the horizontal distance will become extra than the space alongside the curve. Hence, Sag Correction = Horizontal distance – period alongside the horizontal catenary As proven within side the determine below, the curve is believed as a parabola to facilitate the calculation of correction for sag.

Key takeaways:

The chain surveying completed with the aid of using a tape is anticipated to have a few mistakes because of wrong tape measurements. In everyday chaining works, the mistakes are neglected. But for essential and specific survey works in construction, correct tape corrections are provided.

1.17 Survey stations and lines

Survey stations are the points at the start and the end of a chain line. They may also happen at any convenient points on the chain line. Such station may be:

1.   Main stations.

2.   Subsidiary stations. And

3.   Tie stations.

Main Stations.

The stations taken along the boundary of an area as controlling points are known as ‘main stations. The lines joining the main stations are called ‘main survey lines.

Subsidiary Stations.

The stations are on the main survey lines or any other survey lines are known as “subsidiary station”. These stations are taken to run subsidiary lines for dividing the area into triangles, for checking the accuracy of triangles and for locating interior details.

Tie Stations.

Tie stations are also subsidiary stations taken on the main survey lines. Lines joining the tie stations are called tie lines. Tie lines are mainly taken to fix the directions of the adjacent sides of the chain survey map.

Base Line.

The line on which the framework of survey is formed is known as the ‘base line’. It is most important line of the survey. The longest of the main survey lines is considered the base line. This line should be taken through fairly level ground, and should be measured very carefully and accurately.

Check Line.

The line joining the apex points of triangle to some fixed point on its base is known as the ‘check line’. It is taken to check the accuracy of the triangle.

Bearing of a line is the horizontal angle which a line makes with some reference direction also known as meridian.

Important definition

Reduced level: -elevation of any point with respect to mean sea level.

Benchmark: -a fixed point on ground of known reduced level from where levelling work is started and reduced level of all other points are calculated with respect to reduced level of benchmark.

Back sight: -first reading taken after setting up the instrument at any location.

Foresight: -all least readings taken from any instrument location.

Intermediate sight: -all other staff readings other than back sight/foresight

Height of instrument: -reduced level of line of sight at any location of instrument.

H.I.=RL of B.M. +B.S.

R.L. Of next point=H.I.-F.S./I.S.

Survey Lines

It is a line produced on a cast by a surveyor marking the contour in relation with planned path of placement of a restoration is known as survey line.

Chain lines

The lines joining the main stations are called main Survey or Chain lines

Base Line.

The line on which the framework of survey is formed is known as the ‘base line’. It is most important line of the survey. The longest of the main survey lines is considered the base line. This line should be taken through fairly level ground, and should be measured very carefully and accurately.

Check Line.

The line joining the apex points of triangle to some fixed point on its base is known as the ‘check line’. It is taken to check the accuracy of the triangle.

Key takeaways:

The line on which the framework of survey is formed is known as the ‘base line’. It is most important line of the survey. The longest of the main survey lines is considered the base line. This line should be taken through fairly level ground, and should be measured very carefully and accurately.

1.18 Well conditioned triangle

A triangle is stated to be nicely conditioned triangle while no attitude in it's miles neither much less than 30 nor extra than a hundred and twenty. If in a triangle an attitude is much less than 30 or extra than a hundred and twenty is referred to as sick conditioned triangle. An equilateral triangle having every attitude of 60 is a perfect triangle.

A triangle is stated to be properly-conditioned while no perspective in it's miles much less than three hundred or extra than 1200. An equilateral triangle is taken into consideration to be the best-situation or best triangle Well-conditioned triangles are favored due to the fact their apex factors are very sharp and may be positioned via way of means of a single ‘dot’. In this sort of case, there's no opportunity of relative displacement of the plotted point. A triangle wherein an perspective is much less than three hundred or greater than 1200 is stated to be ill-conditioned Well - conditioned triangles aren't utilized in chain surveying. This is due to the fact their apex factors aren't sharp and properly defined, that's why a moderate displacement of those factors may also motive substantial mistakes in plotting.

Key takeaways:

A triangle wherein a perspective is much less than three hundred or greater than 1200 is stated to be ill-conditioned Well - conditioned triangles aren't utilized in chain surveying

1.19 Basic problems

Time.

Time is a not unusual place problem for the land surveyor, however we are not speak me approximately time control or organizational problems. Weather and Seasonal Changes. GIS vs. Paper Streets and Adverse Possession.  The Matter of As-Built Incomplete Model Laws

Relatively clean to administer Can be advanced in much less time (as compared to different records-series methods) Cost-effective, however price relies upon on survey mode Can be administered remotely thru online, cellular devices, mail, email, kiosk, or telephone. Conducted remotely can lessen or save you geographical dependence Capable of accumulating records from a big range of respondents Numerous questions may be requested approximately a subject, giving considerable flexibility in records analysis With survey software, superior statistical strategies may be applied to investigate survey records to decide validity, reliability, and statistical significance, such as the cap potential to investigate more than one variables A extensive variety of records may be collected (e.g., attitudes, opinions, beliefs, values, behavior, factual). Standardized surveys are fairly unfastened from numerous forms of mistakes Disadvantages The reliability of survey records may also rely upon the subsequent factors: Respondents might not experience recommended to offer accurate, sincere solutions Respondents might not experience cushty supplying solutions that gift themselves in a adverse manner. Respondents might not be completely aware about their motives for any given solution due to loss of reminiscence at the subject, or maybe boredom. Surveys with closed-ended questions may also have a decrease validity fee than different query types. Data mistakes because of query non-responses may also exist. The range of respondents who pick to reply to a survey query can be specific from folks who selected now no longer to reply, for that reason growing bias. Survey query solution alternatives ought to result in doubtful records due to the fact sure solution alternatives can be interpreted in a different way through respondents. For example, the solution option “truly agree” may also constitute various things to specific subjects, and feature its very own which means to every person respondent. ‘Yes’ or ‘no’ solution alternatives also can be problematic. Respondents may also solution “no” if the option “simplest once” isn't available. Customized surveys can run the threat of containing sure forms of mistakes

Key takeaways:

Time is a not unusual place problem for the land surveyor, however we are not speak me approximately time control or organizational problems

1.20 Obstacles in chaining

The three main obstacles in chaining of a line are of the following types: 1. Chaining Free, Vision Obstructed 2. Chaining Obstructed, Vision Free 3. Chaining and Vision Both Obstructed.

It now and again takes place that a survey line passes via a few item which includes a pond, a building, a river, a hedge etc. which prevents the direct dimension of that a part of the road which the item intersects. The interfering item in one of these case is referred to as on obstacle. It is important to triumph over boundaries in order that chaining can be endured in a instantly line. Special techniques are, therefore, hired in measuring distances throughout the boundaries.

In this form of obstacles, the ends of the traces aren't inter visible e.g. Growing ground, hill or jungle intervening. Here instances may also arise: (i) Both ends can be seen from any intermediate factor mendacity on the road together with within side the case of a hill. The impediment of this type may also without difficulty be crossed over with the aid of using reciprocal ranging and period measured with the aid of using stepping technique of chaining. (ii) Both ends might not be seen from any intermediate factor together with within side the case of a jungle. The impediment of this type can be crossed over with the aid of using “Random line technique”. In fig. 3.20, allow AB be the road whose period is required. From A, run a line AB’ referred to as a random line, within side the approximate handy course of AB and retain it till factor B is seen from B’ Chain the road to B’ wherein BB’ is perpendicular to AB’ and degree BB’. If some other period AC’ is measured alongside AB’, a factor C may be positioned on the road AB with the aid of using measuring the perpendicular distance = Similarly some of factors may be positioned at the actual line. The line is then cleared and chained.

Chaining Obstructed, Vision Free: The usual impediment of this kind is a sheet of water, the width of which within side the course of dimension exceeds the period of the chain or tape. The trouble is composed in locating the gap among handy factors at the chain line on both aspect of impediment

Two instances might also additionally arise: (a) When the impediment may be chained round, e.g. a pond, a thorny hedge etc. (b) When the impediment can't be chained round e.g. a river.

Obstacles in Chaining Though it's far ideal to pick out stations a good way to keep away from barriers, on occasion the barriers are unavoidable. Various barriers to chaining can be grouped into: (i) Obstacles to ranging (chaining free-imaginative and prescient obstructed) (ii) Obstacles to chaining (chaining obstructed-imaginative and prescient free) (iii) Obstacles to each ranging and chaining. Various techniques of overcoming those barriers are defined is that this article. Obstacles to Ranging These barriers may be in addition labeled into the subsequent categories: (a) Both ends of the road are seen from a few intermediate factors. Intervening floor is an instance of such impediment. By resorting to reciprocal ranging this problem may be conquer. (b) Both ends of the road might not be seen from intermediate factors on the road, however can be seen from a factor barely far from the road. Intervening bushes and trees are the examples of such barriers. This impediment to chaining can be conquer with the aid of using measuring alongside a random line

Key takeaways:

The three main obstacles in chaining of a line are of the following types: 1. Chaining Free, Vision Obstructed 2. Chaining Obstructed, Vision Free 3. Chaining and Vision Both Obstructed

1.21 Field book

Surveyors use Field Books to document each survey information and notes as surveys had been carried out. They frequently incorporate notes approximately homes and topography, astronomical observations for charting coordinates, boundary marks and different details. Field books are long lasting and water-immune to resist the most harsh process sites.

The pocket book wherein area measurements are mentioned is called the 'area ee-e book'. The length of the sector ee-e book is 20 cm x 12 cm and it opens lengthwise. Field books can be of types: Single –line

Chain survey is appropriate within side the following cases: (i) Area to be surveyed is relatively small (ii) Ground in all fairness level (iii) Area is open and (iv) Details to be stuffed up are easy and much less. In chain surveying most effective linear measurements are made i.e. no angular measurements are made. Since triangle is the most effective discern that may be plotted with size of aspects most effective, in chain surveying the region to be surveyed ought to be included with a community of triangles. Figure 12.eleven suggests a standard scheme of overlaying a place with a community of triangles. No perspective of the community triangles ought to be much less than 30º to exactly get plotted role of a station with admire to already plotted positions of different station. As a ways as feasible angles ought to be near 60º. However, the preparations of triangles to be followed relies upon at the shape, topography, herbal and synthetic boundaries within side the field

Key takeaways:

Surveyors use Field Books to document each survey information and notes as surveys had been carried out.

References:

1. Duggal, S.K. Surveying Vol. I and II, Tata McGraw Hill, 2004.

2. Punmia, B.C. Surveying Vol. I and II, Standard Publishers, 1994.

3. Arora, K. R. Surveying Vol. I and II, Standard Book House, 1996

4 N.N Basak. Surveying and levelling