Roads ACT manages road pavements in the ACT, the road network is approximately 5,900 lane kilometres in length and about 20 million square metres in area.
Road maintenance and rehabilitation
Road pavements wearing surfaces have a life expectancy of between 10-20 years (International Infrastructure Management Manual - IPWEA). Road pavements deteriorate over time due to the impact of traffic, particularly heavy vehicles, and environmental factors. As the road surface wears and ages, small cracks develop in the pavement which permit water to enter the underlying surface of the pavement. Water infiltration, combined with the continual stress imposed by the flow of traffic, will considerably weaken the pavement. If this happens potholes, major cracks, pavement deformation and ultimately road failure will result.
Example of a road pavement structure.
Achievement of the design life and beyond of the pavement wearing surface is dependent on resealing the surface of the pavement before water infiltrates into the underlying pavement materials ie: the base and sub base. Preventative resealing of the pavement is the most cost-effective method of maintaining good road condition.
Once a pavement has reached failure condition, or the end of its functional life, resurfacing and remedial maintenance, eg. filling potholes, becomes less and less effective. At this stage alternative options for rehabilitation or reconstruction are considered. These include;
- strengthening the pavement by asphalt overlay,
- reconstruction of the pavement by insitu recycling, which involves breaking down (pulverising) the existing pavement materials, adding stabilising materials, re-compaction and asphalt resurfacing; and
- total pavement reconstruction, which involves the removal of existing pavement materials and subsequent rebuilding of the pavement.
At this stage of road reconstruction safety and road enhancement improvements are also considered. Safety improvements that overcome deficiencies in skid resistance, road geometry and road width are normally justifiable on the basis of reduced accidents and reduced road user costs, ie: wear and tear to your vehicle. Road enhancement, such as the inclusion of on-road cycling facilities or alignment improvements, are implemented if appropriate and effective.