Transport - Road length by local road or state highway and region 2009–2019

Lane length: length of a longitudinal strip of the roadway intended for the passage of vehicles or a specific class of vehicles that is separated from other parts of the roadway by a longitudinal line or lines of paint or raised studs, which includes:
- cycle lane
- lane for the use of vehicular traffic that is at least 2.5 m wide
- lane of a two-way road divided by a centre line.

Road length: length of roads including streets, motorways (except for Territorial Authority data), beaches, places to which the public have access, all bridges, culverts, ferries, and fords forming part of a road, and all sites at which vehicles may be weighed for the purposes of the Act or any other enactment.

Local roads: roads that form a regionally strategic purpose in moving people and goods within regions. These roads are managed by local government.
State highways: roads in New Zealand that form a nationally strategic purpose in moving people and goods nationwide. State highways are a Crown asset that we manage on behalf of central government.

https://nzta.govt.nz/resources/what-is-a-road/what-is-a-road/

At URL provided, select 'Data' in the table row corresponding to Infrastructure > Physical statistics - roads'.

This dataset provides information about the length of urban and rural, sealed and unsealed roads within Road Controlling Authority areas, each Region and Territorial Authority in New Zealand.