Bench mark in surveying refers to which concept?

• A. A definite, permanent accessible point of known height above a datum
• B. A temporary marker with unknown height
• C. A device used to measure distance between points
• D. A type of GNSS receiver

Answer: (A)

A bench mark is a fixed, permanent point in the field whose elevation relative to a defined datum is known and can be relied upon for leveling and establishing vertical control. The defining feature is permanence and a known height above the datum, so surveyors can use it as a stable reference to determine elevations of other points. Because it provides a reliable reference, it stays in place and its elevation remains constant over time, unlike temporary markers whose height isn’t guaranteed. It’s not a measuring instrument or a GNSS receiver; those are tools, not reference points. In practice, a bench mark supports consistent elevation work by serving as the vertical control from which other elevations are measured or calculated.