3/17/2023 0 Comments Datum engineeringThe staff man keeps moving the staff until the cross hair is aligned with it.After that, the surveyor at the levelling instrument targets the staff through telescope.He brings his feet together and places the staff between his feet. To ensure proper verticality of the staff, the staff man stands straight behind the staff. After the instrument has been fixed, a staff man takes the staff and advances to the point where reading is to be taken.For that purpose, the bubbles in the instrument are leveled and centered. The first step is levelling and centering the levelling instrument. As discussed earlier, a levelling staff is always used in combination with a levelling instrument, therefore we take both aspects into account. Leveling Staff Procedure of Taking Readingįollowing steps are involved in taking a reading from a levelling staff. The reading at benchmark is summation of datum height and staff reading at that point. The exact elevation is achieved by subtracting this value from the reading obtained by placing the staff at the benchmark (point of known elevation). The point at which this reading is taken is 1.208 meters above or below a fixed datum. The first number is in meters, the second number in decimeters, and the second last and last number is in millimeters.įor example, we have a staff reading of 1.208, this means 1 meter 2 decimeters and 08 millimeters. Staff reading is the reading at which the cross hair intersects/strikes the staff.
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