If you are driving in alpine areas of NZ (incl Desert Rd in the NI) it is really a good idea to check road conditions before you go.

 NZTA Highway Information www.highwayinfo.govt.nz

Info line for state highways in New Zealand - 0800 44 44 49 (0800 4 HIGHWAYS)

NZTA are the government agency responsible for State Highways in New Zealand.

This is a free service with the latest official highway conditions. Make sure you can quote the state highway number to them and the towns that you will be passing through - hopefully this will then get you the right information eg. Lindis Pass is on SH8 between Omarama and Tarras.

They can also assist you to find out about driver licensing & registering vehicles in NZ. 

NZTA also have twitter accounts for each region of NZ where they will provide updates about Highway conditions. 

@NZTAAkl - Auckland & Northland
@NZTAWaiBOP - Waikato & Bay of Plenty
@NZTACNI - Central North Island
@NZTAWgtn - Wellington
@NZTACWC - Canterbury / West Coast
@NZTAOS - Otago & Southland

 AA Roadwatch Site - http://www.roadwatch.co.nz/

This is a good graphical site & provides lots of reported incidents as well as official incidents. Not always accurate & obviously not practical to use when you are actually driving but has the most information in one place.

Incidents can be reported to roadwatch on *222 (free from mobile).

 AA Road Info Line - Ph 0900 33 222

Unfortunately this is not a free service. Calls cost $1.30/min. They will give you all the same information as present on the AA Roadwatch website

 Police Non-emergency Traffic Line Ph *555 from NZ mobile phones

This is a reporting service for any road incidents or hazards/issues (Bad/unsafe driving, road conditions, animals on roads, etc). This service is run by the NZ Police.

For all Emergencies dial 111