Contour & Cross Sectional Report

Topics: Elevation, Contour line, Cartography Pages: 11 (2724 words) Published: January 29, 2013
No| Title| Pages|
1| Contents| 1|
2| Details of Practical| |
| 3. Objectives| |
| 4. Theory & Principles | |
| 5. Equipment and Functions| |
| 6. Task of team members| |
| 7. Precautions of Practical| |
3| Data| |
| a. Sketches| |
| b. Booking| |
| c. Calculation| |
4| Results| |
| a. Results analysis| |
| b. Value/Photo| |
| c. A3 Plan| |
5| Discussions / Conclusions / Suggestions| |
| a. Question and Answer| |
| b. Conclusion| |
| c. Suggestion and improvements| |
6| Appendix / References| |
| a. Original Documentation| |
| b. Reference| |

1. To carry out longitudinal section (Profile) and cross section. 2. To perform the contour field work using grid method.
3. To learn about the equipment of leveling clearly
4. To document the data and produce the report.

Theory & Principles
The purpose of levelling is to obtain measurements of differences in elevation of objects that are not vertically above each other. The level is an optical instrument that provides a height reference. This reference is a horizontal plane through the axis of the telescope, known as the "Height of Collimation". Once the height of collimation (or instrument height) has been measured the height of other stations can be found by measuring from this plane with a staff. The height of collimation is found by taking a backsight to a staff placed on a bench mark. The staff reading is added to the bench mark value to obtain the height of collimation. Once the height of collimation has been found ground height at any spot below this plane can be found by observing the staff and subtracting the staff reading from the height of collimation. Hence, the formula used in this practical is,

For each station, HPC = (known RL) + BS, and each RL = HPC – (IS or FS) HPC= High of Plane of Collimation
RL= Reduced Level
BS= Backsight
IS= Intersight
FS= Foresight
This method is simpler than rise & fall method but with one checks less, so care should be taken in reduction. LONGITUDINAL SECTION AND CROSS SECTION
For getting the sectional shape of the land, face leveling section is needed. This sectional shape of the land was used in the construction of road, railway, irrigation and etc. The implementation that surveyor got for engineering or construction designer was for determining the actual ground level, level of embankment or cutting, cross-sectional area or volume of soil. Face leveling section was divided into two types: 1. Longitudinal section

* A section that is cut along axis of structure.
2. Cross section
* Section of land across the way from side to side.

Contour is defined as imaginary line of constant elevation on the ground surface. Describe the shape of the land or topography of an area. Terms in contour:
1. Contour line – represent the same connection points height of land above sea level. 2. Gap or distance contour – difference height between two consecutive lines of contour. Gap
Contour line
Contour line

Characteristics of contour:
1. Has a fixed contour interval and the lines cannot be intersect 2. Horizontal area have a wide gap
3. Slope area have a close interval
4. Contour lines do not stop at the some point, but at the limit of the plotting paper. 5. Bay or gorge has a concave contour where the line is in 6. Cape or peak has a convex contour where the line is out.

Draw a contour using:
1. Grid method
2. Cross-section method

Cross section methodGrid method

Precautions of Practical
STEP 1: Establish the position of each station, temporary points and Intersight points. By usingTape Measure 30M and put a peg as mark.| STEP 2: Set up an Auto Level at the first station and perform temporary adjustment to ensure the bubble of...
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