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Problem (2)
A TSI is set up over the SW corner of a property. The TSI height is 5.73' above the corner, measured with a fiberglass tape. The elevation of the top nut on a fire hydrant (FH) across the street is 827.43'.
From the TSI, the following readings are taken
| Point | Reflector Height1 |
Slope distance |
Horizontal angle |
Zenith angle |
| FH | 5.00 | 84.39' | 0°00'00" | 95°30'45" |
| NW | 6.25 | 194.48' | 44°51'55" | 87°05'35" |
| NE | 6.25 | 240.68' | 80°56'30" | 85°48'05" |
| SE | 7.50 | 142.02' | 134°51'35" | 92°23'50" |
1Measured with the same fiberglass tape.
What are the elevations of the four property corners? Compute to 0.01' to minimize rounding error.
Solution
We saw in the previous problem that over short distances, curvature and refraction are too small to affect elevations.
Point SW
Determine the elevation of the TSI at point SW from the fire hydrant, then the elevation of point SW from the TSI.
Point NW
Point NE
Point SE
Solution
| Point | Elev |
| NW | 844.15 |
| NE | 851.91 |
| SE | 927.10 |