There are minimum criteria for condition and availability when maintaining and operating our network. We contract this to consultants and contractors in each of our 25 network management areas around the country.
The different types of contract we use to do this play an important part in ensuring those levels of service are met. We also closely monitor the cost of this work to determine the point at which more than maintenance is required to meet road users' expectations.
We use five contract types to procure maintenance and operations:
All our contracts for state highway maintenance work specify levels of service that must be achieved. These are expressed as either:
We also manage New Zealand's roading standards and guidelines (external link) on behalf of all 74 road-controlling authorities.
Through our maintenance contracts we collect information on the costs of maintenance per year and per kilometre. This is stored in the roading assessment and maintenance management RAMM (road assessment and maintenance management)database. (external link)
The types of data held in RAMM include:
Working with our consultants and contractors, we use this RAMM information to identify the sections of the state highway network where we may have to do renewal and strengthening work. If it costs less to replace or strengthen the road than to continue maintaining it, the renewal work becomes a high priority.
Local authorities also use RAMM to manage the inventory and maintenance of their networks. This has the advantage that a consistent national comparison and compilation of asset data and condition is possible.
To describe locations along the highway for maintenance work, we use a distance-based reference station system. All highways have a nominated 'zero' point (for example, Cape Rēinga is the zero point for State Highway 1 in the North Island) and any point can be described using intermediary points called 'reference stations'.
For example, if you're travelling south on State Highway 1in the North Island, you first meet Lake Taupōon The Esplanade at 01N-695-8500 – that is, 8,500 metres past Reference Station 695, which is roughly 695 kilometres from the start point at Cape Rēinga.
Although we’re increasingly using spatial locations and GPS equipment in some areas, the distance-based reference station system is still a cost-effective, efficient and useful option.