INTRODUCTION OF SURVEYING

INTRODUCTION OF SURVEYING

• Planning and design are based on the results of surveys, and construction is controlled by surveying.

• Surveys cover a wide range of scope and complexity:

  • Stacking out simple structures

  • Extensive and difficult survey requirements in construction of subdivisions, bridges, highways, canals, dams, railroads, etc.

WHAT IS THE DEFINITION OF SURVEYING?

• Delineating a portion of the earth’s surface or subsurface, or of establishing

  the position or boundaries on earth’s surface.

• “Surveying is the art of determining the positions of points on or near the earth’s surface by means of measurements in the three elements of space, namely, distance, direction, and elevation.” – Rayner and Schmidt

• It is the art and science of determining angular and linear measurements to establish the form, extent, and relative position of points, lines, and areas on or near the surface of the earth or on other extraterrestrial bodies through applied mathematics and the use of specialized equipment and techniques.

PLANE SURVEYING

• A type of surveying in which the earth is considered a flat surface, and where distances and areas involved are of limited extent that the exact shape of the earth is disregarded.

GEODETIC SURVEYING

• A type of surveying in which the earth is considered to be spheroidal shape.

• Usually undertaken by government agencies to serve as basis to produce accurate base and topographic maps.

TYPES OF SURVEYS

1. Cadastral Surveys

   • are closed surveys undertaken in urban and rural locations for the purpose of defining property lines and boundaries, corners, and areas.

2. Topographic Surveys

   • made to gather data to produce a topographic map showing the configuration of the terrain and the location of natural and man made objects.

   • The features shown include natural objects such as hills, mountains, rivers, lakes, relief of the ground surface, etc.

   • While the works of man: roads, buildings, ports, towns, bridges, and municipalities.

3. Hydrographic Surveys

   • Surveys bodies of water such as lakes, reservoirs, harbors, oceans and the like. These are made to map shorelines, chart the shape of areas underlying water surfaces, and the measure the flow of streams.

   • Made for the purpose of navigation, development of water supply and resources, flood control, irrigation, etc.

4. Construction Surveys

   • Made to layout, locate, and monitor public and private engineering works.

   • Provides data regarding grades, reference lines, dimensions, ground configuration, and the location and elevation of structures which are of concern to engineers, architects, and builders.

5. Route Surveys

   • involves determination of alignment, grades, earthwork quantities, location of natural and artificial objects in connection with planning, designing, and construction of highways, railroads, canals, pipelines, and transmission lines.

6. Photogrammetric Surveys

   • uses aerial photogrammetry, use photographs with specially designed cameras either from planes, ground stations, or even the use of drones.

INSTRUMENTS IN SURVEYING

Many surveying instruments today evolved from which were earlier used in astronomy. The following instruments were the early forerunners of our present-day surveying instruments:

1. Astrolabe

   • a portable, usually flat instrument made of brass which depicts the position of the prominent stars in the sky relative to the observer’s horizon.

   • It was originally designed for determining altitude of stars.

2. Telescope

   • when crosshairs for fixing the line of sight was introduced, it was only then used in early surveying instruments.

3. Transit

   • It is known as the universal surveying instrument that is invented by Young and Draper.

   • Early transit in surveying was primarily used to accurately measure horizontal angles between points on the ground.

4. Semicircumferentor

   • used to measure and lay off angles and establish line of sight.

5. Plane Table

   • One of the oldest types of surveying instruments used in field mapping.

   • It consists of a board attached to a tripod in such a way that it can be leveled or rotated to a desired direction.

Compass

• is a device indicated direction and is and instrument for navigation.

• In surveying, it is used for the measurement of horizontal angles and the bearing of a line of sight.

SURVEYING MEASUREMENTS

• Measurement is the process of determining the extent, size, or dimension of a particular quantity in comparison to a given standard.

• In surveying, measurements are usually concentrated on angles, elevations, times, lines, and volumes.

• Any surveying measurement is always subjected tot the imperfections of the instrument used, and the different errors inherent in the process of obtaining the measurement.

• There is no such thing as a perfect measuring instrument nor there is a surveyor whose senses are sufficiently perfect to measure any quantity exactly.

DIRECT MEASUREMENTS

• A comparison of measured quantity with standard measuring unit/s employed.

• This method directly measures using chains, tapes, and other types of surveying equipment.

Examples are:

1. Using tape to measure distance

2. Total station to find angle

3. Barometer for atmospheric pressure

INDIRECT MEASUREMENTS

• When it is not possible to apply a measuring instrument directly to a quantity to be measure, indirect measurement is used.

• For this type, the observed value is determined by its relationship to some other known values.

Examples are:

1. Elevation determination using backsight and foresight readings.

2. Determining lot area using angles and distances.

UNIT OF MEASUREMENTS

INTERNATIONAL SYSTEM OF UNITS (SI)

1. Linear, Area and Volume Measurements

   • 1 kilometer (km) = 1000 meter

   • 1 meter (m) = 1000 millimeter

   • 1 millimeter (mm) = 1000 micrometers

   • 1 micrometer (um) = 1000 millimicrometers

   • 1 millimicrometers (mu) = 1000 million micrometers

   • 1 meter (m) = 10 decimeters

   • 1 decimeter (dm) = 10 centimeters

   • 1 centimete (cm) = 10 millimeters

2. Angular Measurements

   The SI Units for plane angles are in radians.

   • 2𝜋 = 360°

   SEXAGESIMAL UNITS

   • measures angles in degrees, minutes, and seconds.

   • It is also known as base 60.

   • 360° = 1 revolution

   • 1° = 60′

   • 1′ = 60"

   CENTESIMAL UNITS

   • gradian (grad or g) is the unit of measure of an angle.

   • 400^g = 1 revolution

   • 1^g = 100′

   • 1′ = 100"

     SIGNIFICANT FIGURES

   • In recording results from values obtained by measurements and computations, it is important to determine which should be retained as significant figures.

   • These are used to reports a value, measured or calculated, to the correct number of decimal places or digits that will reflect the precision of the value.

   • When a measurement is taken, the precision of that measurement is dependent on the equipment used to take the measurement

   • The measurement will have some digits that are certain and one digit that is uncertain or estimated.

   Rules in Significant Figures

   Rule 1:

   • Zeroes between other significant figures are significant.

   • Example for the following vales each of which contains 4 significant figures:

     • 12.03, 35.06, and 40.09

   Rule 2:

   • For values less that one (1), zeroes immediately to the right of the decimal are not significant. The only show the position of the decimal such as (3 significant figures):

     • 0.00325, 0.000468, 0.0230

   Rule 3:

   • Zeroes places at end of decimal numbers are significant such as (5 significant figures):

     • 169.30, 366.00, 11.000

   When computations are to be made from the values of measurement, it is important that enough figures be retained to ensure that the significant figures in the final results are consistent with the precision of the measurement.

STUDENT FIELD PRACTICE

FIELD PRACTICE

• In elementary surveying, the student acquires a certain extent of field practice.

• It is not possible for students to develop into expert instrumentman during the course of performing an ordinary field work (laboratory, field work).

• However. it is expected that the course will give the student a working knowledge of surveying instruments and their uses.

• Members of the student field parties should assume various duties alternately every assigned field work.

• The use of surveying instruments require not only understanding the basic theories and principles of surveying, but also an extensive amount of field practice.

SURVEYING FIELD NOTES

• Surveying field notes constitute the only reliable and permanent record of actual work done in the field.

• If the notes are incorrect, incomplete, or obliterated - the time, money, and effort during survey data gathering are wasted.

• No matter how careful field measurements are made, the survey data may be useless if some of the measurements are incomplete or unrecorded.

• Field notes become the official record of survey, that’s why it is necessary of it to be complete. legible. concise, and comprehensive.

• Field notes are usually worked over in the office into some more advanced form of presentation, such as a map, report, or a computation.

• These are always kept for future reference and may be used by another surveyor some years later.

• It is not possible to predict to what extent the information gathered on most surveys may become of value in the future.

• A need to rerun, extend, or otherwise make use of previous surveys may be required for a related project.

FILED NOTEBOOK

TYPES OF NOTES

• Sketches

• Tabulations

• Explanatory notes - written description of what is done in the field.

• Computations

• Combination of the aforementioned

INFORMATION IN THE FIELD NOTEBOOK

• Title of the Field Work

• Date and Time of day

• Weather Conditions

• Group member names, their designations (chief of party, instrumentman, tapeman, etc.)

• List of equipment used - all survey equipment used must be listed including its make, brand and serial number.

• If all information are known, mistakes committed in the field which are not discovered until the field work is completed could be easier to determined.

• Mistakes are often traced to weather conditions, or equipment that are out of adjustment.

• Correction can be easily made without redoing the whole field work.

FIELD SURVEY PARTY

1. Chief of Party

   • he is responsible for the overall direction, supervision, and operational control of the survey party.

   • He also handles the logistical and technical requirements, and problems of a survey field operations.

2. Assistant Chief of Party

   • takes over the duties of the chief of party during his absence.

   • He conducts site/ground observation and investigation prior to start of survey work.

   • He is responsible for the employment of surveying equipment, instruments, and accessories used during survey field work.

3. Instrumentman

   • his duty is to set up, level, and operate surveying instruments such as transit, engineer’s level, theodolite, sextant, plane table, and etc.

   • He assures that all equipment to be used are in good condition, and in proper adjustment.

4. Technician

   • responsible for use and operation of all electronic instruments required in a field work.

   • He assures that all instruments are all calibrated, functioning properly, and are in proper adjustment.

5. Computer

   • responsible to perform all computations of survey data and works.

   • He utilized electronic calculators, microcomputers, and assist the operation of the computerized surveying systems or equipment.

6. Recorder

   • keeps record of all sketches, drawings, measurements, and observations, taken from a survey field work.

7. Head Tapeman

   • responsible for the accuracy and speed of all linear measurements with tape.

   • He directs and determines the marking of stations to be occupied by surveying instruments, and directs the clearing out of obstructions along the line of sight.

8. Rear Tapeman

   • assists the head tapeman during taping operations.

9. Flagman

   • holds the flagpole, or range pole at selected points as directed by the instrumentman and helps in making measurements.

10. Rodman

    • holds the stadia or leveling rod when sights are to be taken on it.

11. Pacer

    • checks all linear measurements made by the tapeman.

    • He helps the tapeman in assuring that mistakes or blunders are reduced or eliminated.

    • A pacer may also do the job of a rodman

12. Axeman/Lineman

    • he clears the line of sight from trees, bushes, and other obstructions in wooded locations.

    • He is also responsible for the safety and security of the members of the party at the survey site.

13. Aidman

    • his duty is to render first aid treatments to survey members that are involved in snake bites, accidents, and other cases involving their safety, health, and well being.

    • He may also be designated as assistant instrumentman.

14. Utilityman

    • renders other forms of assistance needed by the survey party or as directed by the chief of party.

    • If a survey vehicle is to be used, a utilityman is designated as driver.

    • If the survey party needs to camp out for days in the field, his duty is to setup camp site and its required facilities.

    • They are likewise responsible for handling and transporting survey equipment, accessories, and supplies.