National Height Network

The NHN ensures that important precise levelling control marks are retained and that geometric heights are determined for new control marks when they are established. This enables users to connect their datasets to the official geodetic datum.

The following page summarises the main characteristics of the network.


To provide marks to enable users to connect to official vertical datums


Across North Island, South Island, Stewart Island/Rakiura

Sufficient density along existing levelling routes to enable efficient connection to official vertical datums


Order: 1V (vertical only)
Tier: E (0.25 m)
Class: VI (0.01 m, 3x10-6m/m)
Class evaluation radius: 2 km

Mark characteristics

Precise levelling

Ideally included as part of another network


Sited so that surveyors can easily and safely locate and occupy

Mark access

Physical access to collect conventional observations