hub

In surveying, a hub is a wooden stake, typically 1 to 2 inches in diameter and 12 to 18 inches long, driven into the ground with a nail or tack on top to mark a specific point. This nail provides the precise location that instruments like theodolites or total stations are set up over, or that measurements are taken from. Hubs serve as temporary control points during a survey and can be quickly replaced or removed once the work is complete.

The hub itself is subordinate to the nail: it is the nail head, or occasionally a punch mark beside it, that defines the actual point. The stake simply keeps the nail at ground level and holds it steady against minor disturbance. For rough terrain or soft ground, hubs may be driven at an angle or supported with a small mound of earth. On hard surfaces such as pavement or rock, a separate tack or nail is sometimes set into a lead plug or epoxy anchor instead.

Relationship to other marks

Hubs differ from permanent benchmarks and monument points, which are set in concrete, stone, or iron and may remain for years or decades. They also differ from offset stakes, which are placed nearby to protect a critical point from being stepped on or driven over. A survey party will typically mark a hub with a flag, tape, or nearby witness stake so it can be relocated if covered by vegetation or snow. The relationship between hub location and any offset is always recorded in the field notes.

Wooden hubs will rot if left in place for months, especially in wet ground. In surveys where points must persist longer, surveyors transition to setting actual monuments. The term 'hub' is also used informally for any stake marking a temporary point, and the practice has remained essentially unchanged because it is cheap, quick, and requires no special equipment beyond a hammer and wooden stakes.