Two Peg Test - Report
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1. This document describes the procedure for performing a two peg test to check the accuracy of a leveling instrument. 2. The two peg test involves taking elevation readings from two staffs placed 50 meters apart, and then taking readings again with the level positioned closer to one staff. Any difference in the elevation differences between the two readings indicates an error in the level. 3. The results of the test documented show an elevation difference of 0.014 meters between the first and second readings, indicating the level needs servicing since the acceptable error is less than 0.002 meters.
Two Peg Test - Report
- 1. 1 Soran University Faculty of Engineering Civil Engineering Department TWO PEG TEST Student: Sarchia Khursheed Group: E Date: 20.10.2015 Supervisor: Eng. Anwar Jabbar Introduction
- 2. 2 All instruments are subject to errors. The checking of the instrument (in this case level) is therefore important. The main error is where the line of sight is not parallel to the horizontal line of collimation. In this case levels will not be correct. A test for checking the level is known as the two peg test. Two peg test must be carry out before strating the leveling job to insure the instrument in good condition. This test determines the amount of errors and if an error occurs notify the technician (the level must be serviced). Purpose of Test Purpose of doing this test is to determine the collimation error of a level instrument. Equipments List of equipments and tools need to completing the two peg test: Auto Level Staff Tripod Tapes (50 meters) Marker (Spray) Pen, Paper, and Calculator Procedure Steps of a two peg test:
- 3. 3 1. Establish two points (A and B) approximately 50 meters apart on level ground, and put the level staffs in each point, and the level half way between the two points. 2. Take readings on both pegs, and find the difference in elevation. 3. Move the level as close ass possible to one of the peg (5 meters). Take the two staff readings again. 4. If the difference in height is the same the level is okay. If not, the instrument needs to be serviced. Calculation Peg A Peg B Difference Readings (from middle point) 1.473 1.447 E1 = 0.026 Readings (from point C) 1.457 1.417 E2 = 0.04 ΔE = E2 – E1 = 0.04 m – 0.026 m = 0.014 m Result and Conclusion
- 4. 4 In conclusion we know that the two peg test is very simple, but provides a way to test the accuracy of a level, and help to know which screw to turn (for analog instruments) or menu to follow (for the degital level), it can be adjust to remove the error. For a good or normal level the result from calculation of two peg test must be smaller than 0.002, if the result is greater than 0.002 the level must be serviced. Because the result 0.014 is greater than 0.002 the instrument (level) must be fixed and serviced.