CE 111 Lab #6
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School
Iowa State University *
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Course
111
Subject
Aerospace Engineering
Date
Dec 6, 2023
Type
docx
Pages
4
Uploaded by JusticeIceCrocodile25
1
Lab #6 - Differential Leveling Lab
Due 10/12/2023
Objective Statement:
In this lab, the objective was to understand the concept of differential leveling. With that, we gained experience with automatic levels in differential leveling. For the calculations, our objective is to find the errors in the leveling work and make the appropriate corrections. Introductions:
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Differential leveling is a progressive and repetitive operation, which transfers an elevation from a benchmark point (BM) to the elevation of the instrument. From there it goes to the desired elevation point. The operator of the instrument takes the backsight (BS) of the point of elevation and then reads the measurement on the leveling rod. The reading is added to the known elevation point to get the height of the instrument (HI)
A foresight (FS) is taken from the Instrument to the leveling rod to find the unknown elevation, such as a turning point (TP). This process is continued until returning to the starting point or another known point. Since you go back to the starting point or another BM, you can then check your work by comparing the calculated elevation to the initial elevation. For this lab, the class determined the elevation of the top of fire hydrants. Starting from a known elevation near the State Gymnasium the final destinations of our survey be fire hydrants near fire hydrants south of the Communication Building.
Procedure: ●
Identify all the leveling points (Fire hydrant) given.
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Plan the Location of the Leveling instrument. For 3 leveling points the Level should be relocated at least 3 times or more.
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Place the Leveling instrument in a position where it can spot 2 leveling points i.e. Back sight and fore sight.
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Level the Leveling instrument take the first reading i.e. back sight and note the elevation of the ground using the level rod (Measuring scale).
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After taking the Back sight reading take the fore sight reading and calculate the HI and elevation. ●
Repeat this procedure given above until you get all the leveling points reading.
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Calculate the HI and elevation for all points and do a page check to identify the error.
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Calculate Loop misclosure, permissible misclosure and adjustment and rewrite the elevation in the field book with adjusted elevation. (Note: the First elevation point reading and adjusted elevation reading remains the same).
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Calculations:
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Closure Error
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Starting elevation- final elevation = closure error
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960.00’ - 960.02’= -0.02
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Adjustment
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Closure error/ number of setups = adjustment ○
-.02/ 4= -0.005
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Permissible Misclosure ○
absolute value of loop misclosure*√number of setups
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0.02* √4= .04
Conclusion
In conclusion, the purpose of this lab is to learn and understand the concept of differential leveling using the automatic levels and the measuring rods. Groups had to pay attention and spend extra time understanding both the automatic levels and the measuring rod as they were new pieces of equipment. Setting up the automatic level and making sure that it was level before getting back sights and forward sights in order to ensure that the measurements we were getting were accurate. Also, making sure the measuring rod was as level as possible while getting measurements as the rod being tilted in any direction could have skewed data or caused inaccurate measurements. Going through the procedure the whole group learned how to collected data for differential leveling and in an accurate manner as all of our data was within the error calculation that we expected. Appendix:
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1a) Field Booklet