It is a reference elevation in feet above sea level. A Benchmark (with a capital B) is an elevation marker established by the Federal Governement (USGS)for the use by land surveyors.
what is benchmark and what's the main purpose of benchmark?
The word benchmark is a noun. The plural form is benchmarks.
A benchmark is just a point on the map, so that you can see where on the map you are.
Maps can show elevation with contour lines
It is where the highest point is where the elevation is at and where it starts at
A benchmark is a monument that is a point of precisely measured elevation.
When surveying using a "level" instrument , the "level" instrument is set-up and adjusted to level by adjusting the screws. When surveying you have an instrument person and a rod person. When trying to find the height of the instrument, the rod person places there rod over a "known" elevation, either a benchmark or a temporary benchmark that has a known elevation. To get the height of the instrument, you need to "shoot" the level to the rod person holding the rod on the known elevation, this is called the "Backsight". This elevation will be read by the instrument person, and recorded in the survey field book. This value backsight elevation will then be added to the known elevation of the benchmark or the temporary benchmark, to get the height of instrument. HI = known elevation + BS Height
benchmark (a standard of excellence or elevation against which things are measured)
774 ft is the elevation of Cooper Mountain Oregon at the USGS benchmark located at the summit N 45 27.325, W 122 52.291. 774 ft is the elevation of Cooper Mountain Oregon at the USGS benchmark located at the summit N 45 27.325, W 122 52.291.
The invert level of an existing pipe is the result when you subtract the depth/height of the lowest elevation/level of the inside/inner portion of the existing pipe from the surface reference elevation most commonly known as benchmark (BM). Benchmark (BM) can usually be found on permanent structure in the surface/ground.
Set up the instrument. Get it level. Shoot the gradestick. Know what the actual elevation is. Subtract the actual elevation of the grade you want from the elevation of the benchmark. Add the amount you shot on the stick at the benchmark to the amount you deduced. Shoot the stick at the point you want, and tell your helper to move the stick up and down till you get the right # in your sights. Pretty simple once you get the hang of it. I'm 19 and can do it so...
A temporary benchmark in surveying is a control point that is set by a surveyor to base other points off of. They will assign it an elevation, and other points that are surveyed off of that point will have a relative elevation rather than an absolute elevation.It has no relevance to property lines, right-of-ways, or other surveyed features, and is only used to complete the survey.
A point of known elevation and location is called a benchmark. Benchmarks are established to provide a reference point for measuring heights and locations of other points in the area.
To transfer elevations, BM + BS = HI - FS = Elevation BM - Benchmark BS - Backsight, or a measurement taken on a benchmark HI - height of the instrument FS - Foresight, or a measurement taken on an unknown point
A temporary benchmark in surveying is a control point that is set by a surveyor to base other points off of. They will assign it an elevation, and other points that are surveyed off of that point will have a relative elevation rather than an absolute elevation.It has no relevance to property lines, right-of-ways, or other surveyed features, and is only used to complete the survey.
what is benchmark and what's the main purpose of benchmark?
Invert elevations can usually be found directly on as-built drawings of the sewer facility. The simplest way to calculate an invert elevation of a manhole is to measure the depth of the manhole from the surface to the pipe invert. The invert elevation equals the ground or rim elevation minus this depth. If you do not know the rim elevation or invert elevation, a surveyor must measure the invert and/or rim elevation with reference to a nearby elevation benchmark (see: http://commons.wikimedia.org/wiki/Image:Elevation_Benchmark.jpg). Also, upstream and downstream invert elevations in a manhole typically differ by about 0.1 feet.