DJ wrote:--------------------------------------------------------------------------------
May 1994. 'Public Access', No. 4 / amended June 2002
Public Roads -- A Users' Guide
The key concept behind the law of highways is the right of passage. Your rights, and limitations on your actions, and those of administering district councils, hinge on this concept.
Whether a public road is formed or unformed (including so-called 'paper roads') has no bearing on their legal status, or on your rights of use. There is the same right of passage.
New Zealand public roads are strips of land normally 20 metres wide with ownership vested in district councils. Adjoining land owners have the same rights of use as members of the general public, plus a right of 'frontage' (access) to their property along their legal boundary with the road. They are not 'The Owners' of public roads, as frequently asserted or implied.
The following advice reflects current New Zealand statutory and common law. The direct-actions noted below have been repeatedly 'field-tested' without any legal liabilities falling on the practitioners.
What you can do--
each and every member of the public can assert their right to pass and repass without hindrance, by whatever means they choose (provided it doesn't damage the surface). The right of passage is vested in the public, not councils - their ownership is in the capacility of trustees.
do other things related to passage, e.g., parking, resting etc.
remove 'public nuisances'*, erected without statutory authority, sufficient ( i.e. no more than what is necessary), to enable passage.
* Recommend leaving materials to one side without unnecessary damage. Not every encroachment amounts to a 'nuisance' - needs to be 'an appreciable interference' with, or an obstruction to, your rights of passage such as a lock or barrier. What amounts to 'appreciable interference' is a matter of fact on a case by case basis.
NOTE: There may be liability if stock escapes on to vehicular roads and causes a traffic hazard. If a risk, we recommend removing fencing when stock are absent then immediately notifying owner in writing that fencing is not stock-proof--then their liability.
remove vegetation sufficient for passage (ie. clear tracks).
as an adversely affected member of the public, sue the person responsible for a nuisance, and the district council if it authorised it. There is no obligation to initiate legal proceedings as the sole course of action. Removal of obstructions can lawfully occur independently (the power to assert passage), or in conjunction with legal action.
What you or an adjoining occupier cannot do--
occupy or obstruct a road to the exclusion of the public.
encroach on a road by any building, fence, ditch, or other obstacle, or plant any tree or scrub, without authorisation from the district council (note however that councils cannot lawfully authorise public nuisances).
dig up, remove, or alter in any way the soil or surface or scarp or a road, without authorisation from the council.
damage or remove or alter any gate or cattle stop lawfully erected.
What you must do--
leave a lawfully erected gate in the position (whether open or closed) in which it is found.
What district councils can do--
close roads temporarily to traffic or any specified type of traffic with public notification, for reasons of road construction or repair, resolution of traffic problems, when public disorder exists or is anticipated, for temporary diversion to other roads, for exhibitions, fairs, public functions etc., and to motor vehicle use, or any class of motor vehicle, when climatic conditions may cause road damage.
close roads temporarily (for motor races or other special events) to vehicular traffic, with public notification and right of objection (pedestrian access remains).
'stop' or permanently close roads after a public notification and objection procedure (watch out for public notices in local newspaper). Council decisions to 'stop' roads are subject to a right of appeal to the Environment Court. The key determinate is the need for the road (e.g., provides legal access to individual allotments or the uses to which the road is being put to, now and in the future, and by whom including recreational uses in the context of the overall use by the community), not any perceived need for 'stopping' such as undesirability of public access through inconvenience or loss of privacy for adjoining owners.
grant leases of airspaces above roads, provided that sufficient airspace remains for the free and unobstructed passage of vehicles and pedestrians.
permit in writing the erection of a swing gate with a 'Public Road' sign, or a cattle stop, or both across a road, where it is not practical or reasonable to fence the boundaries of the road.
sue any person in respect of a nuisance arising from an unreasonable interference with the public right of passage.
compel removal, or recover the cost of removal, of an obstruction.
What district councils cannot do--
create a nuisance, or deprive any person of any right or remedy they would have against the council or any other person in respect of any such nuisance.
lawfully authorise obstructions (e.g., locks, fences*, stock yards, buildings) across roads (* fences in association with lawfully erected gates and cattle stops, are lawful).
grant rights of use or occupation that create a public nuisance or interfere with public rights.
What district councils are liable for--
obstructions it has authorised when they become nuisances, should they become aware of them.
permitting an obstruction it has authorised, once it becomes a nuisance, to remain on a road or otherwise fails to abate the nuisance.
What district councils are not liable for--
spending money on road construction or maintenance (a Council discretion).
obstructions to roads of which they have no knowledge.
Caution
1. This is a summary and not the complete law relating to roads. Consult a lawyer.
2. This advice is dependent on the road being properly dedicated.
3. You must be certain you are on the correct alignment.
For a fuller explanation of legal rights and how to research the status and location of roads see
'Public Roads-A Guide to Rights of Access to the Countryside', and
http://www.publicaccessnewzealand.org 
When intending to travel a Paper Road, the check list from this thread so far is: 
Do your research first and make sure it is actually a legal road 
) and now its getting really useful.