Unsealed Roads

We would like to keep you up-to-date with information about unsealed roads.

New road surface material coming...

Having completed extensive testing and investigation of the gravel on our unsealed roads and the gravel available from local quarries, we have started using a new gravel called ‘Tucker Gravel’. Our testing has shown this material to provide a reduction in dust generated, improved water run-off and long term road condition.

Key information

We are aware of community concerns regarding dust, maintenance and condition of unsealed roads in the community which can be subject to weather conditions. We appreciate that not all residents wish to contribute to sealing the road and like to retain a ‘country feel’ provided by an unsealed road.

Every unsealed road has unique characteristics and generally consists of local and imported material to address local traffic use with a focus on maximum life cycle and routine maintenance.

Dust suppression in the form of a salt or brine water (magnesium chloride) has been introduced on some roads deemed suitable for treatment, however feedback from the community and our inspections indicate that this treatment provides only a short life cycle benefit (1 week - 3 months).

Our maintenance team has further investigated road pavement materials and undertaken testing on a number of roads in the municipality with the introduction of a new material 'tucker gravel' which has resulted in a reduction in dust, better water run off, and in turn, improved road conditions.

We are introducing the 'tucker gravel' to our unsealed road network in a staged roll out based on when new material is required on each road.

We will be undertaking continuous monitoring of the performance of this gravel and will assess if traditional dust suppression is require during drier moths to further improve road conditions.  Use of dust suppression will continue to be on a case-by-case basis and reliant on budget availability.

Please be aware that wet weather whilst laying the new gravel or immediately after can result in short term unfavourable road conditions due to excess moisture in the gravel.  Once the gravel has been able to dry and compact down these conditions will not reoccur.

We will continue to regularly monitor the condition of roads affected by wet weather and repair as needed.  During this time reduced speed limits and warning signs will be in place.

Technical information

Unsealed roads are made up of a mix of gravel, sand, silt and clay.  The gravel and sands provides skid resistance and load capacity to the road, clay provides the glue to hold the road together and silts are the worn down gravel, sand and clay.  A balance of gravel, sand, silt and clay is required to produce a long lasting road surface. If there is too much:

  • gravel or sand, the road will break apart and appear like marbles over the surface
  • clay, the surface will become slippery and rut in wet weather
  • silt the road will break apart and will generate a lot of dust.

The Unsealed Roads Manual - Guidelines to Good Practice is produced by the Australian Road Research Board (AARB).  This manual sets out a guide for choosing road materials which are best suited to building unsealed roads.

The table below shows 5 tests to determine if a material is suited to building unsealed roads and how they compare to the 'Tucker Gravel'.

 Material measures Recommended values  Tucker gravel values 
 Stone passing 26.5 millimetre sieve (Avoid unsuitably large stones) 100% 100%
 Material retained on 2.36 millimetre sieve (% of gravel) 20% - 60% 46%

 Ratio of fines to sand (Stability and water resistance of material)

0.2 - 0.6  0.22
 Plasticity Index (Check for right amount of clay) 4 - 15 11
 Linear shrinkage (alternative check for right amount of clay) 2 - 8 2.5

Page last updated: Thursday, 27 June 2019