Fundamentals of Surveying 1 PDF Notes

FUNDAMENTALS OF SURVEYING 1 TOPIC 1 SURVEYING “One of the oldest art practiced by man” IT IS THE ART AND SCIENCE OF DETERMINING ANGULAR AND LINEAR MEASUREMENTS TO ESTABLISH THE...

FUNDAMENTALS OF SURVEYING 1 TOPIC 1 SURVEYING “One of the oldest art practiced by man” 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. TWO GENERAL CLASSIFICATIONS OF SURVEYING: 1) Plane Surveying – is the type of surveying in which the earth is considered to be flat surface, and where distances and areas involved are of limited extent that the exact shape of the earth is disregarded. 2.) Geodetic Surveying – are surveys of wide extent which take into account the spheroidal shape of the earth. These surveys employ principles of geodesy, are of high precision, and the related calculations involve the solving of equations derived from advanced mathematics particularly spherical trigonometry, calculus, and some applications of theory of least squares. TYPES OF SURVEYS: Cadastral Surveys – are usually closed surveys which are undertaken in urban and rural locations for the purpose of determining and defining property lines and boundaries, corners, and areas. These surveys are also made to fix the boundaries of municipalities, towns, and provincial jurisdictions City Surveys – are surveys of the areas in and near a city for the purpose of planning expansions or improvements, locating property lines, fixing reference monuments, determining the physical features and configuration of the land, and preparing maps. Construction Surveys – these are surveys which are undertaken at a construction site to provide data regarding grades, reference lines, dimensions, ground configuration, and the location and elevation of structures which are of concern to engineers, architects, and builders. Forestry Surveys – a type of survey executed in connection with forest management and mensuration, and the production and conservation of forest lands. Hydrographic Surveys – refer to surveying streams, lakes, reservoirs, harbors, oceans, and other bodies of water. These surveys are made to map shore lines, chart the shape of areas underlying water surfaces, and measure the flow of streams. Industrial Surveys – sometimes known as optical tooling. It refers to the use of surveying techniques in ship building, construction and assembly of aircraft, laying-out and installation of heavy and complex machinery, and in other industries where very accurate dimensional layouts are required. Mine Surveys – are surveys which are performed to determine the position of all underground excavations and surface mine structures, to fix surface boundaries of mining claims, determine geological formations, to calculate excavated volumes, and establish lines and grades for other related mining work. Photogrammetric Surveys – a type of survey which makes use of photographs taken with specially designed cameras either from the airplanes or ground stations. Measurements are obtained from the photographs which are used in conjunction with limited ground surveys. Route Surveys – involves the determination of alignment, grades, earthwork quantities, location of natural and artificial objects in connection with the planning, design, and construction of highways, railroads, pipelines, canals, transmission lines, and other linear projects. Topographic Surveys – are those surveys made for determining the shape of the ground, and the location and elevation of natural and artificial features upon it. The features shown include such natural objects as hills, mountains, rivers, lakes, relief of the ground surface, etc; and works of man, such as roads, building, ports, towns, municipalities, and bridges. THE FIELD SURVEY PARTY Chief of Party – the person who is responsible for the overall direction, supervision, and operational control of the survey party. He is also responsible for its logistical and technical requirements, and problems of a field survey operation Assistant Chief of Party – the person whose duty is to assist the chief of party in the accomplishment of the task assigned to the survey party. He takes over the duties of the chief of party during the absence of the chief. He is primarily responsible for the employment of surveying equipment, instruments, and accessories used in the survey operation Instrumentman – the person whose duty is to set up, level, and operate surveying instruments such as the transit, engineer’s level, theodolite, sextant, plane table and alidade, and etc. He sees to it that instruments to be used in a survey operation are in good working condition and in proper adjustment. Technician – the person who is responsible for the use and operation of all electronic instruments required in a field work operation. It is his duty to see to it that these equipments are functioning properly, are regularly calibrated, and are in proper adjustment Computer – the person whose duty is to perform all computations of survey data and works out necessary computational checks required in a field work operation. Recorder – the person whose duty is to keep a record of all sketches, drawings, measurements and observations taken or needed for a field work operation. He keeps table of schedules of all phases of work and the employment of the members of the survey party. Head Tapeman– the person responsible for the accuracy and speed of all linear measurements with tape. He determines and directs the marking of stations to be occupied by the surveying instruments and directs the clearing out of obstructions along the line of sight. He inspects and compares tapes for standard length prior to their use in taping operations and is responsible for eliminating or reducing possible errors and mistakes in taping. Rear Tapeman– the person whose duty is to assist the head tapeman during taping operations and in other related work. Flagman – the person whose duty is to hold the flagpole or range pole at selected points as directed by the instrumentman. He helps the tapeman in making measurements and assists the axeman in cutting down branches and clearing other obstructions to the line of sight. Rodman – the person whose primary duty is to hold the stadia or leveling rod when sights are to be taken on it. Pacer – the person whose duty is to check all linear measurements made by the tapeman. He assists the tapeman in seeing to it that mistakes and blunders in linear measurements are either reduced or eliminated Axeman/Lineman – the person whose duty is to clear the line of sight of trees, brush, and other obstructions in wooded country. He is also responsible for the security and safety of the members of the survey party at the survey site. Aidman–the person whose duty is to render first aid treatment to members of the survey party who are involved in snake and insect bites, accidents, and other cases involving their health, safety, and well being. Utilitymen– the persons whose duties are to render other forms of assistance needed by the survey party or as directed by the chief of party. Where a survey vehicle is used, autilityman is designated as driver. If the survey party has to camp out for days in the field, utilitymen are responsible for setting up the camp site and its required facilities. They prepare and serve meals, and also look after the security of the camp site ERRORS AND MISTAKES ERROR– is defined as the difference between the true value and the measured value of a quantity. It is a deviation of an observation or a calculation from the true value and is often beyond the control of the one performing the operation. MISTAKES – are inaccuracies in measurements which occur because some aspect of a surveying operation is performed by the surveyor with carelessness, inattention, poor judgment, improper execution, misunderstanding of the problem, inexperience, or indifference of the surveyor. A large mistake is referred to as BLUNDERS. Mistakes and Blunders are not classified as errors because they usually are so large in magnitude when compared to errors TYPES OF ERRORS 1. Systematic Errors - This type of error is one which will always have the same sign and magnitude as long as field conditions remain constant and unchanged. It also referred to as CUMULATIVE ERROR. 2. Accidental Errors - These errors are purely accidental in character. The occurrence of such errors are matters of chance as they are likely to be positive or negative in , and may tend in part to compensate or average out according to laws of probability. SOURCES OF ERRORS Instrumental Errors - These errors are due to imperfections in the instruments used, either from faults in their construction or from improper adjustments between the different parts prior to their use. Surveying instruments, just like any other instrument, are never perfect; proper corrections and field methods are applied to bring the measurements within certain allowable limits of precision. Examples of instrumental errors are: a. Measuring with a steel tape of incorrect length. b. Using a leveling rod with painted graduations not perfectly spaced. c. Determining the difference in elevations between two points with an instrument whose line of sight is not in adjustment. d. Sighting on a rod which is warped. e. Improper adjustment of the plate bubbles of a transit or leve Personal Errors - These errors arise principally from limitations of the senses of sight, touch and hearing of the human observer which are likely to be erroneous or inaccurate. This type of fallibility differs from on individual to another and may vary due to certain circumstances existing during measurement. Typical of these errors are: a. Error in determining a reading on a rod which is out of plumb during sighting. b. Error in measurement of a vertical angle when the cross hairs of the telescope are not positioned correctly on the target. c. Making an erroneous estimate of the required pull to be applied on a steel tape during measurement. Natural Errors - These errors are caused by variations in the phenomena of nature such as changed in magnetic declination, temperature, humidity, wind, refraction, gravity, and curvature of the earth. Natural errors are beyond the control of man. However, in order to keep the resulting errors within allowable limits, necessary precautions can be taken. Common examples for natural errors are: a. The effect of temperature variation on the length of a steel tape. b. Error in the readings of the magnetic needle due to variations in magnetic declination. c. Deflection of the line of sight due to the effect of the earth’s curvature and atmospheric refraction. d. Error in the measurement of a line with a tape being blown sidewise by a strong wind. e. Error in the measurement of a horizontal distance due to slope or uneven ground. ACCURACY AND PRECISION ACCURACY indicates how close a given measurement is to the absolute of true value of the quantity measured. It implies the closeness between related measurements and their expectations. PRECISION refers to the degree of refinement and consistency with which any physical measurement is made. It is portrayed by the closeness to one another of a set of repeated measurements of a quantity. Thus, if a set of observations is closely clustered together, the observations is said to have been obtained with high precision. ACCURACY AND PRECISION THEORY OF PROBABILITY PROBABILITY is defined as the number of times something will probably occur over the range of possible occurrences. Different theories of probability are not only applicable to games of chance; they are also used in scientific and engineering measurements such as in surveying. MOST PROBABLE VALUE From the theory of probability a basic assumption is that the Most Probable Value (MPV) of a group of repeated measurements made under similar conditions is the ARITHMETIC MEAN or the AVERAGE. THEORY OF PROBABILITY RELATIVE (ERROR) PRECISION In surveying measurement, Relative Precision (RP) is the ratio of the error to the measured quantity. It is used to define the degree of refinement obtained. It is expressed by a fraction having the magnitude of the error in the numerator and the magnitude of a measured quantity in the denominator. It is necessary to express both quantities in the same units, and the numerator is reduced to unity or 1 in order to provide an easy comparison with other measurements