Road failures can be caused by wet weather events, high traffic volumes, the age of the road, and lack of preventative maintenance.
Each year Council sets out its maintenance and capital works programs as part of the Annual Operational Plan Review. Capital road projects are prioritised based on condition assessments, risk modelling, traffic volumes and available funding. Funding comprises many sources including general revenue, grant funding and Section 94 funds.
Road maintenance includes pothole filling, shoulder grading, road edge break repair, heavy patching, minor patching, road side mowing, gravel road grading, table drain maintenance, drain clearing and tree lopping.
Capital works are required when an asset has deteriorated beyond routine maintenance and a renewal is required. For a road this may involve a full depth pavement reconstruction, new bitumen or asphalt wearing surface, subsurface drainage, and kerb and gutter or table drain improvements. For a bridge or causeway this may be refurbishment of existing components or replacement of the bridge.
Council also receives grant funding for capital works from programs such as the Federal Government's Black Spot Program and Bridges Renewal Program.
Filling a pothole is a temporary fix and often the problem can reoccur depending on wet weather and traffic volumes.
Potholes are filled by one of the following methods:
- The placement of asphalt hot mix directly into the hole, after the hole has been cleaned out and tack coated with bitumen emulsion spray. This is the strongest and most expensive fix, so it is targeted in high traffic, high stress urban areas.
- The Jetmaster truck which uses compressed air to clean the pothole, followed by a bitumen spray tack coat, followed by bitumen mixed with aggregate to fill the hole. This repair is more efficient and many potholes can be repaired in one day, however the fix is not as strong as hot mix, so it is targeted to lower traffic, lower stress rural roads.
- The placement of asphalt cold mix directly into the hole, after the hole has been cleaned and the edges squared. This method is for a fast response usually in wet weather and is not as strong as hot mix.
Patching is a larger repair to a section of stressed road pavement. Patching is a more involved and costly process and is done by excavating out 300mm of pavement for replacement with gravel road base or 100mm for replacement with asphalt. Council develops a heavy patching program each year and is targeted to isolated stressed sections of road where the majority of the road is in good condition.
Resealing is the practice of spraying a new layer of bitumen and applying new aggregate to an existing bitumen road surface. The aim is to intervene on an ageing seal before it becomes too cracked and potholed and the underlying pavement becomes compromised by water infiltration.
A typical reseal should add seven to 10 years life to a road and if regular intervention is done in this way, the life of a road can be greatly extended.
In 2018/19 Council's Reseal Program spend will be $1.2M, this will continue to grow each year thereafter.
- Full depth replacement of the pavement usually about 300mm deep
- Any unsuitable sub-grade (below pavement) replacement
- Sub-surface drainage improvements
- Kerb and gutter and table drain improvements,
- Footpaths and kerb ramps (depending on the project)
- Line marking and signage.
For any reconstruction project the road width, horizontal and vertical alignments will also be assessed against the standards and improvements made as required.
The cost of reconstructing a road is in the order of $100-$250 per square metre, versus about $10 per square metre to reseal a road with a single layer of bitumen. This highlights the importance of undertaking a reseal program each year before roads deteriorate to the point requiring full reconstruction.