Soil and Water Conservation Engineering · Surveying and Leveling · 2 marks · Numerical answer
An overhead benchmark has RL85.168 m. A vertically inverted staff gives backsight3.645 m; foresight on an upright staff at the site is1.523 m. Find site RL in m.
Treat the inverted backsight as negative. Height of instrument=85.168−3.645=81.523 m. Site RL=HI−FS=81.523−1.523=80.000 m. Adding the inverted reading would put the instrument above the overhead mark incorrectly.
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