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Roads, Streets & Bridges

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Maintenance Grading

Council undertakes maintenance grading of unsealed roads in accordance with the adopted:

The adopted Road Hierarchy is based on a practical approach which takes into account traffic counts, school bus routes, residences on the road, as well as the road’s accident history. Whilst grading is scheduled in advance, it is often necessary to alter the program due to the determination of specific roads or unforeseen circumstances.

We attempt to maintain all roads in a serviceable condition within given budgetary and resource constraints. However there are times (eg. during prolonged wet or dry weather) where the condition of unsealed roads may deteriorate and motorists will need to drive to the condition of the road.

Should residents identify a particular problem or are concerned about significant deterioration of a road, please contact us on 6226 1477 or complete an online Customer Service Request and we will arrange for an inspection.

Yass Valley Council provides a weekly 'Schedule of Works' for residents to know what work is being carried out around the LGA. This schedule includes a maintenance grading program. Please visit our news page for the latest update.

Understanding Unsealed Road Grading

What is maintenance grading?
Council grades unsealed roads to reshape and re-compact the road, to reduce ‘lumps and bumps’ and ensure that the road will shed water away from the centre after rain. A grading maintenance schedule is developed each year, depending upon road condition, the amount of use and the effects of drought and wet weather.

Different roads and different sections of a road, may have different grading schedules depending on various priorities and from time to time the order of the program may need to be changed to reflect operational needs. Grading does not occur on any specified date.
During periods of drought and where water is not readily available from nearby dams or running creeks and waterways Council suspends its general grading program to prolong the life of the road and only undertakes maintenance on an ‘as needs’ basis.

What is gravel re-sheeting?
Gravel re-sheeting is when new gravel is added to the road. This is due to the severe deterioration of the road that can compromise the safety of road users. The gravel is generally laid in loose layers and then trimmed and compacted using a grader, water cart and roller so that the new road generally has a depth of about 100mm.

Why does my road lose gravel?
Gravel wears away over time due to the combination of the environment (wetness and dryness), the type and volume of traffic and excessive traffic speed. Softer gravel rock will wear away faster than harder gravel rock.

Unsealed roads are made up of a mixture of gravel of differing sizes, clay and soils. This mixture affects the strength of the pavement and how long it will last. The rock gives the pavement strength and the clay and other soils binds the gravel together. Where possible, the grader drivers will recover as much of the loose gravel as they can during the grading of a road and turn it from the edge back into the centre of the road.

Why is does my road appear to be shrinking?
As the road wears down over time the edges of the road pavement will wear and the width can become less. Road edges can be weakened and deteriorate due to wet weather, vegetation encroachment and by motorists driving close to the edge of the road and cutting corners on road bends.

Width can also be affected over long periods due to grading when additional gravel is not applied.

Can ‘tyning’ the road help to remove potholes and corrugations?
‘Tyning’ is a term used for ripping up the road with a grader. The process allows the road material to be reshaped to reinstate the crown (the high point at the centre of the road). Whilst ‘tyning’ may help repair potholes by providing a smoother surface, it is only appropriate if there is enough gravel on the road surface to be ripped up and reshaped.

Most of Council’s unsealed roads have limited gravel so this process is not used very often. ‘Tyning’ is when the tynes of the grader dig into the road surface and brings material from the lower part of the road pavement to the surface (somewhat like ploughing).

The road is then graded and rolled as normal. When there is limited gravel in the pavement surface, this process may also bring clay and other soil to the surface which further diminishes the pavement by dispersing any gravel that does exist. During wet periods this may cause the road to be slippery and during dry periods the road may become more dust prone.

How about improving the quality of the gravel? 
Council’s quality of gravel varies across the local government area. We extract natural gravel from approved sites on local properties, and we supplement this with materials from commercial hard rock quarries. 

Extracting quarried gravel can be an expensive operation. The harder rock results in a better quality outcome however it is more expensive due to the blasting and crushing activities within the quarry.

Why is my road dusty?
Unsealed roads will always generate some level of dust, because they are made up of gravel, clay and soils and are significantly affected by the environment and driver behaviour.

In very dry conditions roads will become more susceptible to dust generation through the wearing of the clays in the road. When motorists drive at an inappropriate speed (particularly heavy vehicles) excessive dust can also be generated.

Why is my road slippery?
Unsealed roads can be significantly affected by the environment and will be slippery during wet conditions. The degree of slipperiness is often dependent on the quality of the remaining gravel present. Engaging 4WD is highly recommended when this occurs.

Recently graded roads can become boggy or slushy if impacted by a rain event during the grading works or potentially up to 2-3 weeks after the completion of grading. Drying out the road with sunshine and time is the most effective treatment.

Understanding Sealed Road Repairs

Why are some roads in poor condition?
Like most structures, road pavements have a defined life and eventually need to be replaced. Due to the load from traffic over time, the pavement materials weaken and can no longer support the traffic. Water infiltrating the pavement can also cause it to lose strength. This weakening causes the road surface to deform (no longer a flat, even surface), cracks appear in the surface and potholes start to form.

The cost to rebuild all the pavements that have reached this point is more than is available in Council’s annual budget, so it will take many years to fix all the roads.

Council undertakes condition assessments of the roads and data collected is used to determine which roads are programmed for repair in the coming year. The ‘worst’ road is not always selected for replacement. Often intervening on a road nearing failure can be more economic to repair, as the existing pavement materials can be salvaged, strengthened and reused.

This is much more cost effective than fixing a road where the pavement material cannot be salvaged and needs to be entirely replaced.

Why are pothole repairs and other patching necessary?
To keep the road network trafficable, Council crews undertake reactive maintenance repairs to fix defects in the pavement, like potholes. Potholes form when water infiltrates the road surface and the bitumen seal lifts under the action of vehicles driving over. That is why they commonly appear during wet weather. The repeated wheel movements remove more and more gravel making the hole deeper and dangerous.

To remove this hazard, the hole is commonly filled with ‘cold mix’, which is a bitumen based product specifically designed for this purpose. Pothole repairs are necessary to remove the hazard until a more permanent repair can be arranged. With many roads requiring rebuilding, ongoing pothole repairs are sometimes the only viable repair method and the process may need to be repeated numerous times to keep the road trafficable until the pavement is replaced.

Another repair method is a called a ‘heavy patch’. This is where a small section (say 5m x 5m or larger) of the road is rebuilt to remove a localised defect. This repair method is used when surrounding pavement is in otherwise good condition. Heavy patching does require more resources and planning than a pothole repair. So, the pothole repair may be implemented initially to manage the hazard while the heavy patch can be designed and programmed.

Heavy patching is a longer term repair method than pothole repairs and is appropriate when the road is in otherwise good condition. It is more expensive than pothole repairs, so work crews need to be selective on where and how this type of patching is done.

Did you know Council undertakes a Road Resealing Program every year?
Council’s preventive maintenance program helps roads reach their intended life span. The bitumen surface becomes brittle over time, which can lead to cracking that allows water to penetrate in the pavement gravel and soils below. Each year Council undertakes a resurfacing program to rejuvenate the bitumen before it starts to fail.

This is why it may look like we are resurfacing a road that appears to be in otherwise good condition.

How are roads rebuilt?
Road pavements are made up of three main elements:

  • wearing surface or bitumen layer;
  • pavement materials; and
  • sub-grade or underlying soils.

These three elements act together to create a structure that supports the traffic. Engineers consider a number of factors when designing a road pavement including the traffic volume, the type of traffic, available materials and strength of the natural soils to support the weight of the traffic.

Sometimes additives are included in the pavement to strengthen the material. This is called stabilisation. New aggregates for pavements is expensive, so strengthening the existing material in this way, not only saves money from not having to buy new materials, there is also reduced waste disposal costs.

New aggregates are used for the top layer of the new road. The road is then sealed with bitumen or, occasionally, asphalt concrete. If using bitumen, Sometimes Council will place a first coat, known as a prime seal when the works are first completed and a second coat usually 6 to 12 months later.

Rebuilding roads does take a number of weeks. All effort is made to minimise the disruption, but unfortunately motorists will be inconvenienced.

 

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While every endeavour has been taken by the Yass Valley Council to ensure that the information on this website is accurate and up to date, Yass Valley Council shall not be liable for any loss suffered through the use, directly or indirectly, of information on this website. Information contained has been assembled in good faith. Some of the information available in this site is from the New Zealand Public domain and supplied by relevant government agencies. Yass Valley Council cannot accept any liability for its accuracy or content. Portions of the Yass Valley Council information and material on this site, including data, pages, documents, online graphics and images are protected by copyright, unless specifically notified to the contrary. Externally sourced information or material is copyright to the respective provider.

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