Question

The EDM slope distance between two points (A and B) is 2, 556.28 ft (average), and the vertical angles were +2 degree 45'30" from A and -2 degree 45'30" from B (the vertical angles were read at both ends of the line and then averaged using a coaxial theodolite/EDM combination). If the elevation of the instrument station at A was 322.87 ft and the heights of the theodolite/EDM and the target/reflector are all equal to 5.17 ft, compute the elevation of the target station (B) and the horizontal distance to that station.

Answer 1

The elevation of the target station (point B) is calculated to be 328.04 ft, simply adding the instrument's height to the elevation at A, as the average vertical angle is zero. The horizontal distance between points A and B remains the full slope distance of 2,556.28 ft since there's no elevation change affecting horizontal measurement.

Step-by-step explanation:

The student is tasked with computing the elevation of the target station (point B) and the horizontal distance from the instrument station at point A. Given a slope distance and vertical angles measured at both A and B, and considering the instrument and reflector heights are equal, we can calculate the required values.

Calculating Elevation at Point B

To find the elevation at B:

Find the average vertical angle: (2 degrees 45'30" + (-2 degrees 45'30"))/2 = 0 degrees.

Since the average angle is 0, the elevation change is due solely to the instrument's height.

Therefore, the elevation at B is equal to the elevation at A plus the instrument height, which is 322.87 ft + 5.17 ft = 328.04 ft.

Calculating Horizontal Distance

The horizontal distance can be directly taken as the slope distance when the average vertical angle is 0, which means the elevation does not affect the horizontal measurement. Hence, the horizontal distance between A and B is 2,556.28 ft.