SURVEYING 1 CE 215 CHAPTER -2- EXAMPLES and PROBLEMS

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1 Civil Engineering Department SURVEYING 1 CE 215 CHAPTER -2- EXAMPLES and PROBLEMS 1 CONTENTS 1) Permanent Adjustment of Level 1.1) Example ) Assignment 4.1 2) Tape Corrections 2.1) Example ) Example ) Example ) Example ) Assignment ) Example ) Example ) Example

Example 4.1 1) Permanent Adjustment of Level Staff Readings Level A B.h. Remark C 1.579 1.506 0.073 C-A= 30m, C-B= 30m D 1.263 1.258 0.005 D-A= 70m, D-B= 10m h1= R2 - R1, h1= 1.506-1.579 = 0.

2 Example 4.1 1) Permanent Adjustment of Level Staff Readings Level A B.h. Remark C C-A= 30m, C-B= 30m D D-A= 70m, D-B= 10m h1= R2 - R1, h1= = h2= R4 - R3, h2= = h.=.h2 -.h1, h.= = h. = 60m x= h / 60 x = 1m x= /60 x= m h. new = x = m 3 13 mm is bigger than 5 mm, thus needs correction; R3 new= R3 70*e, R3 new= *( ), R3 new= R4 new= R4 10*e, R4 new= *( ), R4 new= h2 new = R3 new R4 new = = =

3 Assignment 4.1 For the following readings find the error then make correction for each error. R3=0.621 m R1=0.290 m R2=0.419 m R4=1.014 m A 40 m C 40 m B 20 m D Setup 1 Setup 2 1.Erroneous or Incorrect Tape Length Corrections (Absolute Length) Ca=(C/l)*L Ca=(l-l /l)*l 2) Tape Corrections 2.Temperature Corrections 3.Tension Corrections (pull) 4.Sag Corrections 5.Slope Corrections 6 3

4 Table Slope Corrections If the length L is measured on the slope as shown in Fig. below, it must be reduced to its horizontal equivalent L cos θ. The required slope correction is 8 4

Example 4.2 You must lay out two points that are exactly 100.000 m apart. Field conditions indicate that standard conditions apply except the measured temperature is 27ºC.

5 Example 4.2 You must lay out two points that are exactly m apart. Field conditions indicate that standard conditions apply except the measured temperature is 27ºC. Determine the distance to be laid out. 9 Example 4.3 A 30-m tape is used with a 100N force instead of the standard tension of 50N. If the x-section area of the tape is 1.8 mm2, what is the tension error per tape length? 10 5

6 Example 4.4 A measurement of m was recorded with a 30-m tape that was only m long under standard conditions. What is the corrected measurement? 11 Example 4.5 A 50-m tape weighs 2kg and is supported at its end points and at the 8-m and 25-m marks. If a pulls of 6 kg is applied, determine the: a) Correction due to sag between the 0-m and 8-m marks, the 8-m and 25-m marks, and the 25-m and 50-m marks. b) Correction due to sag for one tape length, and c) Correct distance between the ends of the tape. 12 6

7 ANS; 13 Assignment 4.2 A 30-m tape is supported only at its ends and under a steady pull of 8 kg. If the tape weighs 0.91 kg, determine the sag correction and the correct distance between the ends of the tape. 14 7

8 Example 4.6 A line AB between the stations A and B was measured as using a 20 m tape, too short by 0.05 m. Determine a. The correct length of AB, b. The reduced horizontal length of AB if AB lay on a slope of 1 in 25, c. The reading required to produce a horizontal distance of m between two pegs, one being 0.56 m above the other. 15 Solution; 16 8

The following being the slopes for the various segments of the line: Calculate the true

9 17 Example 4.7 A tape of standard length 20 m at 85 F was used to measure a base line. The measured distance was m. The following being the slopes for the various segments of the line: Calculate the true length of the line if the mean temperature during measurement was 63 F and the coefficient of thermal expansion of the tape material is per F. 18 9

10 Solution; 19 Example 4.8 A base line was measured by tape suspended in catenary under a pull of 145 N, the mean temperature being 14 C. The lengths of various segments of the tape and the difference in level of the two ends of a segment are given in Table. If the tape was standardized on the flat under a pull of 95 N at 18 C determine the correct length of the line. Take ; Cross-sectional area of the tape = 3.35 mm2 Mass of the tape = kg/m Coefficient of linear expansion = per C Young s modulus = MN/m

11 Solution;

12 = Corrected Length = = m 23 12

Measurement of Horizontal Distances. the distance between two points means the horizontal distance

Measurement of Horizontal Distances the distance between two points means the horizontal distance Pacing Mechanical Devices Taping * Tachymetric Photogrammetric * Electronic Distance Measurement (EDM)