This policy details the approach taken by the Timaru District Council (TDC) on road surfacing in the District.
There are three main types of surface used on New Zealand’s roads and highways:
- Asphaltic Concrete
- Slurry seal.
Asphaltic concrete is a semi-rigid surfacing that has a smooth appearance and produces a low level of road noise when driven over. Asphalt provides a more robust and higher strength road surface. It is generally used on higher volume traffic roads, roads with a higher numbers of heavy vehicles, roads with frequent turning movements such as parking, or where smooth roads are desirable.
Chip-seal consists of a thin layer of stones set in bitumen. It has a rough appearance when in good condition, but may wear smooth with age and frequent use. Chip-sealing is the most common resurfacing treatment used in New Zealand. It is lower cost than asphalt and generally the default surfacing.
Slurry seal is a thin micro-texture surfacing comprising a specially graded aggregate mixed with an emulsion binder. It has properties of both chipseal and asphalt, with a similar look to asphalt. There are four different types; based on aggregate size and each are used in different situations. Slurry seal has a limited lifespan but is less expensive.
The decision on when a road needs to be resurfaced is influenced by the age and condition of the road. When deciding which type of surfacing to use, a number of factors need to be considered. These include but are not limited to:
- vehicle volumes;
- type of vehicles;
- pavement loading
- condition of existing surface and pavement – i.e. cracking, bitumen brittleness, and repair history.
3.0 Key Definitions
- Council - The Timaru District Council or any officer of the Timaru District Council delegated by the Council to take action in relation to any particular law and / or bylaw, or to undertake the duties of a Council Officer under the law / bylaw, and any person appointed especially / generally by the Council to enforce the provisions of this law / bylaw.
- NZTA - New Zealand Transport Agency – A Crown entity that provides financial assistance for roads on behalf of the government. They are also the State Highway controlling agency.
- Pavement - Pavement, also known as road surface, is the durable surface material laid down on an area intended to sustain vehicular or foot traffic, such as a road or walkway.
- Road resurfacing -Road resurfacing work includes asphaltic concrete, chip seal, slurry and metalling surfacing on road carriageways, shoulders, services lanes, cycle lanes, intersections, car parks, and others.
- All roads in industrial areas shall be surfaced with asphaltic concrete.
- All Central Business District (CBD) roads shall be surfaced with asphaltic concrete.
- Road classification (hierarchy) shall have the minimum surfacing outlined in the table below, with the type of surfacing used being finally determined by an engineering assessment.
- All roads subjected to high wear and tear (e.g. cul-de-sac heads, roundabouts, sharp bends, aprons/main road intersections) shall generally be asphaltic concrete.
- Slurry seal can be used as an alternative to asphaltic concrete, in limited circumstances.
Roading Network Classification (Hierarchy)
Adopted District Services Committee 26 April 2016