What does 'grid north' refer to in surveying?

Grid north refers to a direction calculated based on map projections. In surveying, grid north is established by the coordinate system used on a map. It represents the direction that is aligned with the grid lines on a map projection, which often does not coincide with either true north (astronomical north) or magnetic north due to the curvature of the earth and the method of representing the three-dimensional surface of the earth on a two-dimensional plane.

Understanding grid north is essential for surveying tasks because it provides a consistent reference for mapping and navigation within the specified coordinate system. It is particularly useful in contexts where precise calculations and measurements are needed, as surveyors often work with data based on grid coordinates rather than relying on magnetic or true north, which can vary based on location and other factors.