Benchmarking (hobby)

[2] 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.

[5] Other websites offer maps of the locations (and PIDs) of marks in each individual state of the U.S.[6] Until 2023, Geocaching.com had a section of its site devoted to benchmarking.

Additionally, changes in the surrounding buildings, roads, or terrain over decades may make the descriptions obsolete, as some marks have been removed due to construction or buried over time.

Benchmark hunters also frequently carry a compass (to follow directions gleaned from the datasheet), a probe (like a long-bladed screwdriver) to search for buried marks, a trowel (or a small shovel) to uncover buried marks, a whisk broom (to clear away debris), and one or more tape measures of various lengths, used in taping out referenced distances found on the data sheets.

Handheld GPS receivers are often used to get within a few yards probable error of a mark that has adjusted coordinates.

Disks can also be set in rock ledges or boulders and in the concrete of a large structure such as a building, bridge abutment, or the base of a tower.

The name of the mark (or the "station" it locates) is usually stamped into its surface, along with the date on which it was set (or re-set, since markers that have been destroyed, can be replaced).

They are typically tall, prominent, and well-defined points like a smokestack, the peak of a water tower, or a church spire.

However, many of these objects have been altered or replaced by similar nearby structures and no longer mark the original location, so careful identification is required.

U.S. benchmarks were commonly placed on public buildings, such as courthouses, post offices, city halls, and older schools.

Searching for trig points is more popular than hunting benchmarks in the UK, but there is considerable overlap in participation.

These are concrete pillars, about 4 feet tall, which were used by the Ordnance Survey in order to determine the exact shape of the country in a project known as the retriangulation of Great Britain, which was carried out from 1936 to 1962.

These are maintained so they can be used as accurately located anchor points for differential GPS comparisons and are re-surveyed every five years to calibrate for any geological movements of the ground.