Huge thanks to @eric_yu for picking this up and getting it working on a new service after Google discontinued the Fusion Tables service the original map was hosted on.
The map below shows all ‘metal’ roads in NZ over 5km long.
By default the map only shows metal roads longer than 5km. To see all metal roads in New Zealand click “Map & Tool” then the “Layers and Legend” option in the upper-right corner and enable the “nz_metal_roads_all” layer.
If the map is too slow loading on this page, you can access the map directly here.
This map is based off data provided by Land Information New Zealand (LINZ), changes to a roads status since the LINZ data was last updated e.g roads being sealed or temporarily or permanently closed will not be reflected in the map below.