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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 ...
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 ...
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 ).
While original survey methods were largely manual, the current surveying task is simplified by the use of Global Navigation Satellite System technology, allowing the most precise surveying standards yet. [75] The Ordnance Survey is responsible for a UK-wide network of continually operating GNSS stations known as "OS Net". These are used for ...
The Ordnance Survey established the observatory in 1915 to contribute to the measurement of a national vertical datum defined by mean sea level.The subsequent 6-year measurement campaign at the observatory, conducted from 1 May 1915 to 30 April 1921, determined the value of mean sea level as 4.751 m (15.59 ft) below the level of the brass bolt benchmark inside the hut.
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.
The Association of Transport Coordinating Officers (often known by its acronym "ATCO") was formed in 1974, [1] joining initially senior Public Transport officers of local government around the UK. Although limited to 'lead officers', the organisation spread quickly from just upper tier county authorities to all transport authorities around the UK.
The nearly perfect squareness and north–south orientation of the Great Pyramid of Giza, built c. 2700 BC, affirm the Egyptians' command of surveying. [2]A recent reassessment of Stonehenge (c.2500 BC) suggests that the monument was set out by prehistoric surveyors using peg and rope geometry.