Benchmark (surveying) in the context of "Australian Height Datum"

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⭐ Core Definition: Benchmark (surveying)

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 repositioned in the same place in the future. These marks were usually indicated with a chiseled arrow – specifically a broad arrow – below the horizontal line. A benchmark is a type of survey marker.

The term is generally applied to any item used to mark a point as an elevation reference. Frequently, bronze or aluminum disks are set in stone or concrete, or on rods driven deeply into the earth to provide a stable elevation point. If an elevation is marked on a map, but there is no physical mark on the ground, it is a spot height.

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👉 Benchmark (surveying) in the context of Australian Height Datum

The Australian Height Datum was introduced in 1971 as the official vertical datum for Australia, and thereby serves as the benchmark to which all height measurements are referred. The Australian Height Datum is an amalgamation of decades of spirit levelling work conducted by numerous state and territory authorities across the country, and was corrected to align with the mean sea level observations of thirty tide gauges positioned around the entire coastline. While it remains the published vertical datum for all surveying and engineering operations performed throughout Australia, newer technologies have uncovered numerous deficiencies, offsets and distortions within the Australian Height Datum, leading to discussions about defining a new Australian vertical datum.

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Benchmark (surveying) in the context of Survey marker

In surveying and geodesy, a marker (also called a mark, monument, or station) is an object firmly installed to indicate points on the Earth's surface with known coordinates. A benchmark is a type of survey marker that indicates elevation (vertical position). Horizontal position markers used for triangulation are also known as triangulation stations. A set of interrelated geodetic markers form a geodetic network. An active station or reference station is occupied permanently with a measurement instrument, such as GPS/GNSS continuously operating reference stations (CORS).Benchmarking or trigpointing is the hobby of searching for these marks.

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Benchmark (surveying) in the context of Benchmarking (hobby)

Benchmarking, also known as benchmark hunting, 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 other reference marks. Like geocaching, the activity has become popular since 1995, propelled by the availability of online data on the location of survey marks (with directions for finding them) and by the rise of hobbyist-oriented websites.

In 2022 Geocaching HQ informed that they will remove Benchmarking from the Geocaching.com website.

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LINKED FROM (PARENTS)
← Survey marker ← Australian Height Datum ← Benchmarking (hobby) ← Trigpointing ← Geodetic marker
LINKS TO (CHILDREN)
Ordnance Survey → Surveying → Level staff → Broad arrow → Survey marker → Spot height →