topographical surveying & earthwork calculations

Leah Perez of 411/09/10Lab Report: Lab #10- Topographic Surveying & Earthwork Calculations

Laboratory #10- Topographic Surveying & Earthwork Calculations

Introduction: The objective of this laboratory experiment is to complete a topographic survey by measuring the

elevations of the ground surface on a tract of land devoted to a proposed building. The elevations will be found using the Total Station and then used in earthwork calculations. These calculations will include the amount of material to be removed from the site and added to the site and also the cost for each of these operations. A major goal of this lab is also that it be conducted with little to no errors.

Formulas Used: Total Station Elevation= Station A Elevation + Prism Height + Change in Elevation (V) Elevation= Total Station Elevation – (V + Prism Height), disregard sign of V Reduced Elevation= Ground Elevation – Grade Elevation Area CutAA = ½w(h1+h2A)+w(h2B/2+h3+h4+h5/2) Area CutBB and CC= ½w(h1+h2A)+w(25-x)h3+w(h3/2+h4+h5/2) Area FillBB and CC= ½h2B(x) Volume Cut1= (Area CutAA+ Area CutBB)/2 (L) Volume Cut2= (Area CutBB+ Area CutCC)/2 (L) Volume Fill1= (Area FillAA+ Area FillBB)/2 (L) Volume Fill2= (Area FillBB+ Area FillCC)/2 (L)

Other Information Used: Cost to Export Material: $10 per cubic yard Cost to Import Material: $18 per cubic yard

Procedures: Each surveying team will set up their Total Station on the tract located at the intersection of Dean

Keeton and San Jacinto Streets. Here the change in elevation from the Total Station to the desired point will be measured.

Equipment Required: Total Station Rod and Prism Tripod Tape Measurer

1) Each team will set up their Total Station at the center of the proposed building site. Make sure that the Station is level and that there are no obstructions between the Station and any of the flags.

2) Set up the rod-and-prism at the BM (A) and take the elevation. This will be the elevation of the Total Station, which will be used in the calculations.

3) Now, set up the rod-and-prism at each of the flags progressively and then use the Total Station to measure the change in elevation of each point.


4) Also, make sure to measure the height of the rod-and-prism as this will be used for the calculations.

5) Once all of the elevations and changes in elevation are measured, use Microsoft Excel to put the data into tabular format.

6) Use the programming function of Excel to do the calculations using the formulas given above. 7) The prices per cubic yard, given above, should be used to calculate the cost of importing and

exporting material to and from the building site.

Data & Analysis: In the following section all of the data from the lab will be presented in tabular form as generated in Microsoft Excel. A discussion will follow that will talk briefly about any errors that may have occurred and their origins.

Table #1: Elevations

Station

Change in Vertical Distance "V" (ft)

Total Station

Elevation (ft)

Elevation (ft)

BM (A) -5.49 542.91 532.7500+0N -4.93 542.91 533.3125N -2.88 542.91 535.3650N -1.20 542.91 537.0475N -0.50 542.91 537.74100N -1.75 542.91 536.4950+0N -6.99 542.91 531.2525N -4.76 542.91 533.4850N -0.66 542.91 537.5875N -1.09 542.91 537.15100N -2.55 542.91 535.69100+0N -7.22 542.91 531.0225N -4.63 542.91 533.6150N -1.78 542.91 536.4675N -2.58 542.91 535.66100N -2.75 542.91 535.49

Table #1 shows the measured change in vertical distance along with the calculated elevations, which were based on the Total Station’s elevation.

Table #2: Prism HeightPrism Height (ft)

4.67

Table #2 simply states the prism height, which was used to calculate all of the elevations.Leah Perez of 411/09/10Lab Report: Lab #10- Topographic Surveying & Earthwork Calculations

Table #3: More Elevations, Cut/Fill Areas and Volumes

Station

Ground Elevation

(ft)

Grade Elevation

(ft)

Reduced Elevation

(ft)Cut Area

(ft2)Fill Area

(ft2)

Cut Volume

(yd3)

Fill Volume

(yd3)00+0N 533.31 530.75 2.56

251.00 0.00

391.60 4.55

25N 535.36530.75 4.61534.75 0.61

50N 537.04 534.75 2.2975N 537.74 534.75 2.99100N 536.49 534.75 1.7450+0N 531.25 530.75 0.50

171.92 4.92

25N 533.48530.75 2.73534.75 -1.27

50N 537.58 534.75 2.83

256.71 9.83

75N 537.15 534.75 2.40100N 535.69 534.75 0.94100+0N 531.02 530.75 0.27

105.32 5.70

25N 533.61530.75 2.86534.75 -1.14

50N 536.46 534.75 1.7175N 535.66 534.75 0.91100N 535.49 534.75 0.74

Table #3 shows the remainder of the calculated elevations, the calculated cut and fill areas, and the calculated cut and fill volumes.

Table #4: Cut & Fill CostsScenario # Cost $

1 7419.052 6971.55

Table #4 shows the costs of two different scenarios. The first scenario accounts for the cost of exporting all of the cut volume and importing all of the fill volume. The second scenario accounts for the cost of exporting all of the cut volume, but using the excess fill volume already available. The costs per cubic yard of the imported and exported materials are given in the Introduction.


Discussion:The main objective of this lab was to measure and calculate all of the elevations, areas, volumes

and costs of the given tract of earth with as few errors as possible. Although all of the calculations seem reasonable, it is still necessary to consider where some errors might have arisen.

The first place that errors may have entered the data was in the fieldwork. When measuring the elevations with the Total Station, there were many obstructions such as trees and bushes. This may have caused some of the readings to be off. Also, human error may have arisen when leveling the total station or the rod-and-prism. All of these errors are legitimate concerns, but they would only have a miniscule effect on the data set as a whole.

Also, errors may have arisen when the calculations were being done on Microsoft Excel. When entering the programs into Excel it is important to make sure that the formula makes sense and that the parenthesis used are appropriate. It may take multiple tries to come up with the proper combination of parenthesis and multiplication signs. This could account for large-scale errors that could potentially lead to the rejection of an entire set of data. In the case of this lab, it can be assumed that all of the calculations are correct and that they are logical.

In this experiment, all of the possible errors were considered and the data was double-checked. All of the data seems logical and consistent. For this reason, all of the objectives of this lab have been met and the lab can be considered a success.

Conclusion:Topographical surveying is a key skill for Civil Engineers. By learning the fundamentals of

surveying, Civil Engineers are able to obtain a deeper understanding of the projects that they work on. When designing a building or bridge, or other structure, it is important for Civil Engineers to be able to consider the foundations they plan to build on and know how the earth and soil can be manipulated for their use. By knowing the basics of topographical surveying, Civil Engineers can build safer and more cost effective structures.

topographical surveying & earthwork calculations

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