Fundamentals of Surveying PDF

Fundamentals of Surveying Instructor: Engr. Winnie Rossette B. Flores Reference Book: Elementary Surveying by Juny Pilapil La Putt Measurement of Horizontal Distances 01 02 Measurement Distance by of Distance Pacing...

Fundamentals of Surveying Instructor: Engr. Winnie Rossette B. Flores Reference Book: Elementary Surveying by Juny Pilapil La Putt Measurement of Horizontal Distances 01 02 Measurement Distance by of Distance Pacing 03 04 Distance by Illustrative Taping Problems 01 Measurement of Distance  The accurate determination of the distance between two points on any surface is one of the basic operations of plane surveying. Measurement of Distance  If the points are at different elevations, the distance is the horizontal length between plumb lines at the points. Measurement of Distance  If the points are at different elevations, the distance is the horizontal length between plumb lines at the points. Measurement of Distance  In many instances measurements are taken along an inclined line. Measurement of Distance  These distances, however, are subsequently reduce to their equivalent on the horizontal projection for use. Measurement of Distance  The choice depends on the purpose for which the measurement is intended, the required precision, the cost, and other conditions. Measurement of Distance Commonly employed methods of linear measurement: Pacing Taping Tachymetric Graphical Commonly employed methods of linear measurement: Mathematical Mechanical Photogrammetric Electronic Device Measurement 02 Distance by Pacing Distance by Pacing Pacing consists of counting the number of steps or paces in a required distance. A pace is defined as the length of a step in walking. It may be measured from heel to heel or from toe to toe. Distance by Pacing Distance by Pacing In surveying, pacing means moving with measured steps; and if the steps are counted, distances can be determined if the length of a steps are counted, distances can be determined if the length of a step is known. Distance by Pacing Counting strides instead of paces is sometimes preferred by surveyors. A stride is equivalent to two paces or a double step. Distance by Pacing Counting strides instead of paces is sometimes preferred by surveyors. A stride is equivalent to two paces or a double step. Distance by Pacing Pacing furnishes a rapid means of checking measurements taken by other methods. It is suitable in determining approximate distances in situations where a low precision of measurement is sufficient. Distance by Pacing Distances by pacing are sufficiently accurate for small-scale mapping, for locating details and transversing with the plane table, and in reconnaissance surveys. Distance by Pacing Pacing is also used for many purposes in geology, forestry, engineering, and agriculture. Distance by Pacing Under average conditions, a good pacer will have little difficulty in pacing distances with a relative precision of 1/200. Results could be 1 per cent of accurately measured distances. Unless a mistake has been made in counting, it will seldom be more than 3 percent in in error. Distance by Pacing Under average conditions, a good pacer will have little difficulty in pacing distances with a relative precision of 1/200. Results could be 1 per cent of accurately measured distances. Unless a mistake has been made in counting, it will seldom be more than 3 percent in in error. Distance by Pacing To pace a distance, it is necessary to first determine the length of one’s pace. This is referred to as the pace factor.  Methods that can be used to calibrate one’s pace Determine the Adjust one’s pace average length of to some an individual’s predetermined normal step length Distance by Pacing The length of a pace varies with different persons. This can be determined by walking along a line of known length on level ground at a uniform gait, and counting the number of paces it takes to negotiate the stretch. The last pace is estimated to the nearest quarter pace. Distance by Pacing It is advisable to do this in at least five or more trials in order to determine the average number paces. The pace factor is then determined by dividing the known distance by the average number of paces required to transverse it. It is expressed in meters per pace. Distance by Pacing Any unknown distance may then be approximately calculated by determining the number of paces (preferably the average) one takes to negotiate it and multiplying this by one’s pace factor. Distance by Pacing It is important to walk naturally when calibrating one’s pace and in pacing distances. Care should be taken to walk along a straight line. A slight deviation to the left or right of the line will definitely affect the accuracy of pacing. Distance by Pacing Also, an attempt to make each step a predetermined length is tiring and will only give less accurate results. Factors that affect the length of pace: - weight of - speed - roughness of clothing and of pacing the ground shoes used - fatigue on - age and sex - Slope of the the part of of the terrain the pacer individual Distance by Pacing The pace will also differ when going uphill or downhill. Pacing downhill will produce fewer steps than pacing the same distance uphill. Distance by Pacing In general, the length of the pace decreases as any of these factors increases, except the speed. Distance by Pacing If the distance to be paced is quite long, it is advisable to bring along a mechanical counter for recording the number of paces taken. Distance by Pacing A device, called a pedometer, may be hand carried to register the number of paces. Another device used is the passometer which is strapped to the leg of the pacer. This device will register a pace by impact each time either foot touches the ground. Illustrative Problem No. 1 A 45-m course, AB, on level ground was paced by a surveyor for the purpose of determining his pace factor. The number of paces for each trial taken are shown in the accompanying tabulation. Trial Line Taped Dist No. of Paces Mean 1 AB 50 2 BA 53 3 AB 51 45.0 52 4 BA 53 5 AB 52 6 BA 53 Illustrative Problem No. 1 A 45-m course, AB, on level ground was paced by a surveyor for the purpose of determining his pace factor. The number of paces for each trial taken are shown in the accompanying tabulation. (a) Determine his pace factor. (b) If the surveyor then took 771, 770, 768, 770, 772, and 769 paces in walking an unknown distance CD, what is the length of the line? (c) Assuming that the taped length of line CD is 667.0 m, determine the relative precision of the measurement performed. Illustrative Problem No. 2 In five trials of walking along a 90-m course on fairly level ground, a pacer for a survey party counted 51, 52.5, 51.5, 52.5, and 51.5 strides respectively. He then started walking an unknown distance XY in four trials which were recorded as follows: 88.5, 89, 88, and 87 strides. Determine the following: (a) Pace factor of the pacer (b) Length of line XY (c) Percentage of error in the measurement if the taped length of XY is 150.5 meters. Plate No. 2 1. A surveyor counted 50, 52, 53, 51, 53, and 51 paces in walking along a 45-m course laid out on a concrete pavement. He then took 768, 771, 772, 770, 769, and 770 paces in walking an unknown distance XY. His pace factor should be equal to ____. Plate No. 2 2. In Question 1, the length of XY based on the pace factor of the surveyor is equal to ____. Plate No. 2 3. A surveying student had recorded the following after repeated pacing: First distance = 100 m No. of paces: 142, 145, 143, 146.5 Second distance = ? No. of paces: 893.5, 896, 891.5, 897 Find the second distance in meters. Plate No. 2 4. A student recorded the following number of paces after walking a distance of 50 m repeatedly as 71.5, 72.0, 70.0, and 69.5. He wanted to measure the distance between two points C and D. He recorded the following number of paces from C to D or back as 465, 468, 463, and 460. What is the distance from C to D? Plate No. 2 5. A line 125 m. long was paced by a surveyor for four times with the following data 161,165, 159 and 158. Then another line was paced for five times with the following results, 520, 525, 524, 522 and 518. Determine the following: (a) Pace factor (b) Number of paces for the new line. (c) Distance of the new line Plate No. 2 6. A student recorded the following repeated paces of a given line: 456, 448, 462, 447, 452, 455. If his pace factor is 0.628 m/pace, what is the approximate length of line in meters? Plate No. 2 7. A line 100-m, long was paced by a surveyor for four times with the following data: 142, 145, 145.5 and 146. Then another line was paced for four times again with the following results, 893, 893.5, 891 and 895.5. Determine the following: (a) Pace factor (b) Number of paces for the new line (c) Distance of the new line  03 Distance by Taping Distance by Taping The use of a graduated tape is probably the most common method of measuring or laying out horizontal distances. Distance by Taping Taping consists of stretching a calibrated tape between two points and reading the distance indicated on the tape. Distance by Taping Taping is a form of a direct measurement which widely used in the construction of buildings, dams, bridges, canals, and many other engineering as well as non- engineering activities. Distance by Taping Taping may vary from a relative precision of about 1:1000 to 1:25000 or better. Distance by Taping Calibrated ropes, cords, and lines were used by surveyors for many centuries. Distance by Taping The used of steel tapes only came about during the beginning of the twentieth century. Before the advent of the steel tape, the chain was used for linear measurements. Distance by Taping The used of steel tapes only came about during the beginning of the twentieth century. Before the advent of the steel tape, the chain was used for linear measurements. Distance by Taping The used of steel tapes only came about during the beginning of the twentieth century. Before the advent of the steel tape, the chain was used for linear measurements. Thank you!