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An Ordnance Survey cut mark in the UK Occasionally a non-vertical face, and a slightly different mark, was used. The term benchmark, bench mark, or survey benchmark originates from the chiseled horizontal marks that surveyors made in stone structures, into which an angle iron could be placed to form a "bench" for a leveling rod, thus ensuring that a leveling rod could be accurately ...
Survey markers, also called survey marks, survey monuments, or geodetic marks, are objects placed to mark key survey points on the Earth's surface. They are used in geodetic and land surveying . A benchmark is a type of survey marker that indicates elevation ( vertical position ).
Benchmark (surveying) – fixed reference point of known elevation with respect to which RL of other points is determined. Benchmarks can be arbitrary or permanent, the former is used for calculation of reduced levels for small survey works and the latter is used to calculate the elevations of significantly important locations and points.
The complete unit is normally mounted on a tripod, and the telescope can freely rotate 360° in a horizontal plane.The surveyor adjusts the instrument's level by coarse adjustment of the tripod legs and fine adjustment using three precision levelling screws on the instrument to make the rotational plane horizontal.
National survey departments of each country determine RLs of significantly important locations or points. These points are called permanent benchmarks and this survey process is known as Great Trigonometrical Surveying (GTS). The permanent benchmarks act as reference points for determining RLs of other locations in a particular country. [4] [5 ...
The dumpy level was developed by English civil engineer William Gravatt, while surveying the route of a proposed railway line from London to Dover. More compact and hence both more robust and easier to transport, it is commonly believed that dumpy levelling is less accurate than other types of levelling, but such is not the case.
Benchmarking, also known as benchmark hunting, [1] is a hobby activity in which participants find benchmarks (also known as survey markers or geodetic control points). The term "benchmark" is used only to refer to survey markers that designate a certain elevation , but hobbyists often use the term benchmarks to include triangulation stations or ...
A benchmark is usually set on the side, marked with the letters "O S B M" (Ordnance Survey Bench Mark) and the reference number of the trig point on a plaque called a "flush plate". Within and below the visible trig point, there are concealed reference marks whose National Grid References are precisely known.