Surveying (312339) Manual Practical No.2 Determine the area of open field using chain and cross-staff survey
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| Surveying (312339) Manual Practical No.2 |
The area of the open field can be determined by using chain and cross staff survey where the main survey line is the longest line of survey work and the offset is made perpendicular to that line. This is the most suitable method of area calculation for an open field.
Chain and cross-staff survey is used to locate the boundaries of a field and to determine its area. A chain line runs through the center of the area which divides the area into several triangles and trapezoids. The offsets to the boundary are taken in order of their chainages.
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| Chain and cross-staff survey. |
Procedure:
1. First collect the all instruments as per mentioned in point no VII from the survey lab.
2. Let, A and B are the two points in the field through which the baseline is passing.
3. Do the ranging for the line AB by using the direct method of ranging.
4. After ranging of line AB lay the chain over line AB.
5. After that select the approximate points of offset and fix the arrow there.
6. Take the open cross staff place on the line AB on the predefined point of offset.
7. one observer will bisect the ranging rod of any one of the end stations and another observer will bisect the ranging rod fixed on the end of the offset.
8. Accurate and simultaneous observation of both observers will set the perpendicular offset to the main survey line.
9. Then measure the distance of offset on the baseline and also measure the distance of the offset line.
10. Set more offset to the main line and note down the observations and measurements.
11. Record and draw all the accurate observations in the field book.
Observation Drawing:
Readings :
Results:
Total Area of the field=260.3 Sq. m
Practical Related Questions:
1. Distinguish between offset settings by open cross-staff and line ranger.
Answer:
2. Explain types of offset.
Answer:
Conclusion
By taking measurements we successfully determine the area of open field using chain and cross-staff surveys.
