The PSMA Transport & Topography (T&T) dataset includes vector data for:
Airports & airport runways
Railway lines and stations
Hydrology and minor water boundaries
National Parks, Urban Parks and reserves
The complete set of T&T layers meets a range of demographic, spatial analysis and cartographic applications.
The THC contains a three-digit code that specifies whether the street is a local road, national highway etc.
For examples, please refer the different coloured road layers in the map below.
This links to the same column within PSMA G-NAF.
The GRC identifies whether a given road segment is at ground level, above ground (e.g. an overpass) or below ground (e.g. a tunnel).
The GRC finds use within routing and navigation applications.
Above layers are sourced from Transport & Topography
Note: THC refers to the Transport Hierarchy Code