Auckland Transport (AT) is responsible for sealing unsealed roads in the Auckland region.
The Auckland region and Hauraki Gulf islands have more than 7,300km of legal road, of which approximately 863km (12%) is unsealed.
The majority of unsealed roads are in the former Rodney District (78%), with the remainder in the gulf islands, west and south Auckland.
The level of funding for seal extensions identified in Auckland Council’s Long Term Plan totals $10 million over the 3-year period from 2015 to 2018. This is a significant investment, but the length of the unsealed road network still means this funding has to be prioritised.
AT prioritises road sealing using the criteria contained in the Seal Extension Guidelines.
The criteria considers traffic volume, including heavy commercial vehicles, houses and amenities close to the road, safety (traffic accidents), road gradient (steepness) and regional and local priority. The highest weighting for prioritisation is given to traffic volume as vehicle movements are the primary cause of dust.
The prioritsation produces a ranking of all the unsealed roads compared to the available budget in the Long Term Plan.
The highest priority unsealed roads have now been identified and a 10-year seal extension schedule has been developed from that list.
Cost of sealing
There is no typical or standard cost per kilometre to seal an unsealed road. Sealing changes a road’s physical characteristics, a driver’s expectations and encourages higher speeds.
To mitigate these changes, it is often necessary to widen the road, undertake geometric and safety improvements including increasing the radius of bends and corners, the provision of road markings and road signs, and strengthening the road foundation. Land acquisition or the construction of retaining structures is a feature of many sealing projects. It is also necessary to improve the collection and disposal of storm water to prevent water getting into the foundation layers. This prolongs the life of the sealed road.
As of February 2016, work is progressing to complete the sealing of Matakana Valley Road. This is AT's highest priority project and will be completed by May 2016.
A contract has also been awarded for the design for sealing the next 3 highest priority sites:
1. Takatu Road (4.5km).
Stage 1: Weather permitting, anticipated to be complete October 2016.
Stage 2 & 3: Detailed design to be completed in November 2016.
Stage 2 & 3: Construction expected to be complete in May 2017.
2. Silver Hill Road (1.8km).
Construction works awarded 15 July 2016.
Construction expected to be complete in November 2016.
3. Monowai Road (3.9km).
Detailed design expected to be complete in March 2017.
Construction expected to be complete in March 2018.
The sealing of Takatu Road will begin in April 2016 and be completed by March 2017. The sealing of both Silver Hill Road and Monowai Road will follow.
The scope of work includes not only pavement sealing, but also retaining walls, road restraint systems, traffic control (signage, road marking and reflective road studs) and drainage.
Priority list of all unsealed roads
AT has produced a priority list of all of the unsealed roads in Auckland.
A trial of dust suppressants is being currently being carried out in Kaipara. The trial is evaluating 5 different pavement compositions to determine the best approach to introducing dust-suppressant solutions in the Auckland region.