Object: – Plotting building block by the use of cross staff.
Equipments: –
1. Ranging rod – 3 Nos.
2. 30 m Chain – 1 Nos.
3. Arrow – 5 Nos.
4. Metallic tape (30m) – 1 Nos.
5. Cross staff with stand – 1 Nos.
Procedure: –
1. First of all first ranging rod is established at point A and makes fixed station taking measurement revising point A to two permanent structures.
2. Second ranging rod is established at point B and for makes fixed station taking measurement revising point B to two permanent structures.
3. Established grid line A to B using ranging procedure by judgment of eye and laying chain on it.
4. Remaining ranging rod established at exiting corner of object and sight by open cross staff. Let’s meeting point is P.
5. Measure distance of AP and P to sighted object by chain (on grid line) and metallic tape (between P to sighted object).
6. Next object sighted by cross staff in both directions to grid line.
7. Distance between objects to meeting point is noted in field as well as on grid line.
8. Repeat the process until completion the work.
9. Plot plan of field condition or building block by help of field observation.
Observation table: –
Figure:
Precautions: –
1. The ranging rod should be established correctly state at all points.
2. The judgment of line should be taking correctly during established ranging rod at a point.
3. Distance between surveyor’s eye and reference station (eg. A, B and C) should be minimum one meter.
4. The cross staff should be states during sight both station and observations take accurately.
We are thankful to Er. Praveen Kumar Pandey for submitting this very useful topic to us.
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