Rajiv Gandhi College of Engineering and ResearchBe Ist Year Sem-I

Basics of Civil EngineeringUnit II - Surveying

SURVEYING

PLAN AND MAPS

Plan: Graphical representation of building structure like residential, commercial, public, bridge, dam etc. to a smaller scale such as 1:20, 1:50, 1:100 etc. is called as plan,

Maps: graphical representation of very bigger land like land of city, land of nation to a greater scale such as 1:1000, 1:5000, 1:10000 etc. is called maps. For example map of Maharashtra, map of India, map of city like Pune, Nasik.

Type of maps and their use

Type of maps

1) Surveying maps2) Thematic maps.

Surveying maps: Following are the various types of maps:1) Topographic maps2) Engineering maps3) Geographic maps4) Cadastral maps

Topographic maps: It shows natural and artificial feature on the surface of earth. Surveying done for this purpose is called topographic surveying.

Engineering maps: There maps show the detail of engineering project e.g. roads, dams, and bridge. Surveying done for this purpose is called engineering surveying.

Geographic maps: These are about the political boundaries of country and used by general public. Surveying done of this purpose undertaken by state agency.

Maps, representation of geographic area usually a portion of earth surface, drawn or printed on a flat surface. In most instances a maps is a diagrammatic rather than pictorial

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representation of terrain, it usually contains a number of generally accepted symbols, which indicate the various natural, artificial or cultural, feature of area, and it covers.

Cadastral maps: Theses shows ownerships right of individual or communities. Surveying done for this purpose is called cadastral surveying.

Topographic maps Engineering Maps

Geographic maps Cadastral Maps

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Thematic maps or special maps: These are special maps used for special purpose. A tool to communicate geographical concept such as distribution of population density, climate, movement of good, land use etc. is called thematic maps

THEMATIC MAPS

DIGITAL MAPPING

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Digital mapping (also called digital cartography) is the process by which a collection of data is compiled and formatted into a virtual image. The primary function of this technology is to produce maps that give accurate representations of a particular area, detailing major road arteries and other points of interest. The technology also allows the calculation of distances from once place to another.

Though digital mapping can be found in a variety of computer applications, such as Google Earth, the main use of these maps is with the Global Positioning System, or GPS satellite network, used in standard automotive navigation systems.

Working of digital mapping:

GPS receivers collect data from "at least twenty-four GPS satellites" orbiting the Earth, calculating position in three dimensions.The GPS receiver then utilizes position to provide GPS coordinates, or exact points of latitudinal and longitudinal direction from GPS satellites.The points, or coordinates, output an accurate range between approximately "10-20 meters" of the actual location.The beginning point, entered via GPS coordinates, and the ending point, (address or coordinates) input by the user, are then entered into the digital map.The map outputs a real-time visual representation of the route. The map then moves along the path of the driver.If the driver drifts from the designated route, the navigation system will use the current coordinates to recalculate a route to the destination location

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Application of digital mapping

1) Computer Applications Computer programs and applications such as Google Earth and Google Maps provide map views from space and street level of much of the world. Used primarily for recreational use, Google Earth provides digital mapping in personal applications, such as tracking distances or finding locations.2) Scientific Applications The development of mobile computing (PDAs, tablet PCs, laptops, etc.) has recently (since about 2000) spurred the use of digital mapping in the sciences and applied sciences. As of 2009, science fields that use digital mapping technology include geology (see Digital geologic mapping), engineering, architecture, land surveying, mining, forestry, environmental, and archaeology.3) GPS Navigation Systems The principle use by which digital mapping has grown in the past decade has been its connection to Global Positioning System (GPS) technology. GPS is the foundation behind digital mapping navigation systems.

SURVEYING

Definition: Surveying or land surveying is the technique, profession, and science of accurately determining the terrestrial or three-dimensional position of points and the distances and angles between them. These points are usually on the surface of the Earth, and they are often used to establish land maps and boundaries for ownership or governmental purposes.

Use of survey

(i) Plans prepared to record property lines of private, public and government lands help in avoiding unnecessary controversies.

(ii) ( Maps prepared for marking boundaries of countries, states, districts etc., avoid disputes.

(iii) Locality plans help in identifying location of houses and offices in the area

(iv) Road maps help travelers and tourist

(v) Topographic maps showing natural features like rivers, streams, hills, forests help in planning irrigation projects and flood control measures.

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(vi) For planning and estimating project works like roads, bridges, railways, airports, water supply and waste water disposal surveying is required.

(vii) Marine and hydrographic survey helps in planning navigation routes and harbors.

(viii) Military survey is required for strategic planning.

(ix) Mine surveys are required for exploring mineral wealth.

(x) Geological surveys are necessary for determining different strata in the earth crust so that proper location is found for reservoirs.

(xi) Archeological surveys are useful for unearthing relics of antiquity.

(xii) Astronomical survey helps in the study of movements of planets and for calculating local and standard times.

Primary division of survey

1) Plane surveying.2) Geodetic surveying.

Plane survey

1) It is that type of surveying in which the mean surface of the earth is considered as a plane and spheroid shape is neglected.

2) This survey is done on smaller area less than 250km2

3) Required accuracy is competitively low4) It is used for both location as well as construction of different class of work.Page | 6

Geodetic survey

It is that type of surveying in which shape of earth taken into account. All line lying in surface are curved line

1) This survey is done on large area greater than 250 km2

2) High accuracy is required.3) To obtain accurate maps of wide area and control for all other survey.

FUNDAMENTAL AND PRINCIPAL OF SURVEY

The fundamental principles upon which the surveying is being carried out are1. Working from whole to part.2. To locate a point by at least two measurement.

The purpose of working from whole to part is 1) To localize the errors 2) To control the accumulation of errors

PRINCIPLES OF SURVEYING

To work from whole to part:- To work from whole to the part means that entire area or a very large area from the area to be surveyed is first considered and then its smaller parts are considered. Working by this procedure enables to prevent the accumulation of possible errors in the surveying work of larger area.

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The principle to work from whole to part can be well understood by the following example.

Suppose a big piece of land PQRST is to be surveyed. Then control points i.e. stations P, Q, R, S and T are established at each of the corners of land. Then the rectangular area is subdivided into two triangles PQR and RPT by joining stations P and R. Further subdivision of triangle PQR can be done by selecting another station M on the line PR and framing the triangles PQM and QMR. Than first of all survey carried out for small triangle PQM and QMR and then it will continue up to the large area. This principle is used for minimizing the errors in the surveying.

2) To locate a point by at least two independent processes:-

In surveying, the relative positions of points are located by measurements from at least two points of reference whose positions are known.

In short the position of new points from the two known points can be fixed or locating by taking

a. Linear measurements,b. Angular measurements c. Both linear and Angular measurements.

In this method two points are selected in the field and distance between them is measured.

Then relative positions of the other points in the field can be located from these two reference points.

For example from known positions of P and Q , the position of a new point R is fixed or located by measuring any of the following:-

a) By the perpendicular distance RS and distance QS:-

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b) By the two lengths PR and QR.

c) By the angle ‘α’ measured at Q and the length QR.

MODERN SURVEY METHODS

When the work is limited and small and where high degree of accuracy is not needed, the conventional survey instruments can be used like chains, plumb bob, measurement tape, etc. However there are certain engineering works which demand high accuracy and speedy work. Here conventional instruments cannot be used, because of less accuracy and the cost of time. With the development of electronics in the last three decades, new electronic equipments have been developed for the accurate measurement of distance and angles. Hence modern survey techniques can be employed which make use of modern electronic equipment. The distance measuring equipments are Electronic distance meters and the Angle measuring

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equipment is digital theodolite. Similarly digital planimeters have been developed to measure the area of irregular figures.

Digital Theodolite Digital Planimeters

Electronic Distance Meter

Necessity of Modern survey methods

1. In case of long bridges, where the alignment of piers and distance between the piers are to be checked.

2. In an industrial shed, where centre to centre distance of columns and their alignments are to be checked.

3. Locating points of curves for a railway line or a tunnel.4. Locating the existing structures which are spread over a large area.5. Locating alignment & distance between the transmission line towers.

6. Locating the boundaries of city, state, countries for map making

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(1) Electronic distance meter (EDM)

There are some engineering works where accurate measurement of distance becomes absolutely necessary. Linear measurement becomes very difficult when terrain is very rough with valleys or steep hills. EDM has been developed which gives an accuracy of 1 in 105 for ranges up to 50 km.

Classification of electronic distance meter

1) Based on the range measurement:-A) Short range: - Up to 5km with an accuracy of +5mm or -5mm which use infra red

light wave as the signal.B) Medium Range: - Up to 100km with an accuracy of +50mm or -50mm. These

instruments use electronic signals or micro wave.C) Long Range: - Above 100km & use radio waves.

2) Based on the precision:-A) Less precise: - Standard deviation of one measurement greater then ± (5mm + 5x10-

6mm).B) Moderately precise:- Standard deviation of one measurement greater then ± (5mm +

1x10-6mm).C) Highly precise:- Standard deviation of one measurement greater then ± (1mm +

1x10-6mm).

3) Based on the degree of integration with theodolite:-A) Telescope mounted instruments: - EDM mounted on the telescope of theodolite have

separate lines of sight, but parallel to each other.B) Electronic Tachometer: - EDM and digital theodolite have coaxial optics. i.e. line of sight

of each is combined into one.

Uses of Electronic distance meter (EDM)

1) To measure horizontal, vertical and sloping distance between two points.2) To get the elevation of remote objects.3) To set the points at a predetermined distance along the grid lines.4) To set the alignment of the electronic poles or towers and columns of an industrial

buildings.

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(2) Light Amplification by the stimulated emission of Radiation (LASER)

Laser survey equipment is making a fast track into construction or building surveys. This process is much more technologically advanced than any other type of survey instruments used for construction. There are many types of laser equipment such as the laser level, single or dual grade laser, rotating and straight line lasers. Laser levels are becoming more and more common in construction surveys today.

The main unit automatically emits a continuous laser beam that sweeps a full rotation of 3600 so as to allow the operator to mark any location easily. The beam detector gives the relative position of the beam with an easy to read display and audible tones for quick and precise marking. Laser level instrument is waterproof and hence all the important components are protected from wet weather.

Uses of LASER

1) It can be used for alignment purpose, positioning, leveling with the help of laser levels in civil engineering construction.

2) It provides a quick and independent check of gradients for pipe lines, roads and railways.3) Laser plumbing is used in controlling verticality of tall buildings.4) It can be used for establishing a reference line for trenching or for laying out canal alignment.5) Used for cutting of steel plates with speed as high as 2.5m/min.

(3)Total station

It is combination of EDM instrument and electronic theodolite. It is also integrated with microprocessor, electronic data collector and storage system. Microprocessor unit processes the data collected to compute:-

1) Average of multiple angles measured.2) Average of multiple distances measured.3) Horizontal distance.4) Distance between any two points.5) Elevation of objects.6) All the three co-ordinates of an observed point.

Advantages of Total station 1) Field work is carried out very fast.2) Accuracy of measurement is high.3) Manual errors involved in reading & recording are eliminated.4) Calculation of co-ordinates is very fast and accurate.

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5) Corrections for temperature and pressure are automatically made.6) Computers can be employed for map making.

Uses of Total station

1) To measure horizontal and vertical angles.

2) To obtain the horizontal distance, inclined distance and vertical distance between various points.

3) To get the three dimensional co-ordinates of a point in space.

4) To find the length of a missing line.

5) To find the elevation of an object.

6) To locate the points at a predetermined distance along the grid lines

(4)DIGITAL PLANIMETER

A digital planimeter is used to find the area of an irregular surface quickly. It works on in built nickel cadmium storage battery. An electronic circuit measures the pulses of the rotary encoder and the area is displayed in digital form.

Special features:-

1) Measurement of area of regular and irregular figures.2) It measures in Metric & British system of units i.e. mm ,cm ,m ,km , inches and feet etc. 3) The higher unit is shifted automatically, if the measured number exceeds 8 digits during operation.

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4)The resolution in the line measurement is as high as 0.05mm.5) It provides a wide range of scale ration covering from 1/10-7 to 1/107 .6) It has around 40 hours backup of the battery.

Uses:- 1) To find the area of an irregular figure directly form to the desired scale.2) Averaging of the area is done to get the mean area accurately.3) It is possible to find the perimeter of an irregular shaped area.

(5) G.I.S and G.P.S

Difference between G.I.S and G.P.S

GIS (Geographic Information Systems) is tool to display and analyze information geographically. GPS (Global Positioning Systems) is a technology that uses satellites to give one its position on the Earth with the aid of a GPS device or unit. GPS can be incorporated into GIS by using a GPS device to collect points, lines, or polygons, which can be imported into a GIS application for future analysis and interpretation.

GEOGRAPHICAL POSITIONING SYSTEM (GPS)

The Geographical Positioning System (GPS) is a satellite navigation system used for determination of precise location and providing a highly accurate time reference almost anywhere on the earth or in the earth orbit. It uses an intermediate circular orbit (ICO) satellite

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constellation of at least 24 satellites. It precision is about 20m. It has been designed 7 controlled by U.S. department of defense.

Advantages:-

1) Inter-visibility of two stations on the earth is not required.2) Operations are weather independent.3) It can be used around the clock.4) Time required for establishing the position of point is much less.5) Man power required is less.6) 3-D co-ordinates are obtained.

Uses of GPS

1) Application to surveying: - like geodetic, topographical and cadastral surveys.2) Applications to geology:- includes mineral exploration and mining , earth crust movements.

3) Applications to navigation:- includes offshore positioning like shipping and fishing boats, general aircraft navigation and space craft tracking.

4) Application to military: - navigation for Army, Navy, Air force. 5) Application to water resources and environment management: - Design and planning of

dams, spillways, hydroelectric power projects, canals etc is greatly simplified using GPS. 6) Vehicle guidance system. 7) Used for communication tower site survey. 8) Used for mine exploration.

GEOGRAPHICAL INFORMATION SYSTEM

The Geographical information System (GIS) is computer software which gives information of any area. GIS can present many layers of different information; hence GIS technology is latest and one of the best new research tools. A GIS can combine geographic and other type of data to

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generate map and reports. It is used for collect data, manage and interpret location based information in a planned and systematic way. In GIS data can be collected once and used many times

Uses of GIS

GIS is a relatively broad term that can refer to a number of technologies and processes, so it is attached to many operations, in engineering, planning, management, transport/logistics and analysis.

• Disaster management:-in case of floods, earthquakes and landslides to find the safest and shortest route for emergency transportation.

• Town and country planning:-planning various aspects of the city such as land use ,transportation, water supply and irrigation scheme.

• Water distribution analysis• Traffic management analysis• Soil analysis• Site feasibility analysis• Environment impact analysis• Volume or Area analysis of catchment• River or canals pattern analysis• Temperature and humidity analysis

Government agenciesMany government agencies use GIS to help in planning and organizing their geographic data. GIS is not limited to federal use, local and state governments also use GIS to keep track of the properties, public works, roads, and more within their jurisdiction. Examples of agencies using GIS include the National Park Service, the Army Corp of Engineers, North Carolina Department of Trasportation .

Emergency ServicesMany police departments, fire departments and other emergency services have begun to use GIS to help in their daily operations. GIS software can help officials track crime, find the shortest route to emergencies and more. After the events of Septemeber 11th GIS has also become a primary technology in Homeland Security. Examples of GIS use in these fields.

Other BusinessesReal estate agents and bankers are using GIS to track properties, property values, and tax information. Health care professionals are using GIS to track the spread of disease and wellness information. Communication technology companies use GIS in planning of their utility expansions. Weather forcasting also uses GIS technologies. A host of other businesses use it for marketing purposes.

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University questions :-

• State various types of maps and their uses(5m)• Explain GIS & GPS with their applications(6m)• Explain principles of surveying(4m)• Short note on (2.5m) • Digital planimeter • Total station• EDM

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