Where D - HORIZONTAL DISTANCE a = the angle subtended by the targets. Example 2-11: A 2-m long subtense bar was first set up at A and subsequently at B, and the subtended angles to the bar, as read from a theodolite positioned somewhere along the middle of line AB, were recorded as e°24'51" and Determine the length of AB. e°20'30", respectively.

Q: An instrument was set up over TBM 1, and backsights onto point A before sighting onto B. The…

A: To Calculate :- The angle measured at point C (BCD)

Q: Based on the level loop problem. What is the calculated elevation of BM_10 ?

A: Given: The reduced level of BM10  is 701.32'.   To Determine: The calculated elevation of BM10.

Control Survey and Geodetic reductions

Control surveys or survey controls are used to establish reference points as a basis for various construction activities. Vertical and horizontal control points are to be established in a control survey to increase accuracy. After establishing the control points, all other types of surveys such as topographic, right-of-way, aerial mapping, construction layout, boundary surveys, and utility mapping can be worked upon so that control networks can be formed. The place from which the observations are made is called a survey station.