Building Climate Resilient Unsealed Roads
Building Climate Resilient Unsealed Roads
Bland Shire Council conducted risk assessments in climate adaptability within the shire. Our roads infrastructure was identified as a high risk to significant impact from climate change, particularly high temperatures and reduced rainfall. Council sought to complete a trial of various road treatment methods to identify practices and products that would deliver sustained benefits to the environment such as reduced water usage, less raw materials required, reducing carbon footprint, as well as providing cost effectiveness to ratepayers. Bland Shire Council was awarded a grant from the Increasing Resilience to Climate Change program. As part of Bland Shire’s Unsealed road treatment trial, council will make results available to other NSW Councils and its project partners.
Bland Shire Council’s unsealed roads network encompasses the entire LGA with a combined length of more than 2500km. Unsealed roads within the Bland Shire Council consist of gravels, clay and loamy soils. The unsealed roads are maintained on a regular basis, the frequency depends on Council’s Road Hierarchy, extreme weather events such as floods, funding, ratepayer complaints and damage by heavy vehicles. Roads may be re-sheeted with gravel from quarries or wet graded with in situ soils. The Shire covers an area of 8560 square kilometres and a population of approximately 6018. Main Industries in the Bland Shire include mining, egg production, sheep and cattle grazing and broad acre cropping
The unsealed roads network deteriorates at various rates depending on materials, product quality, weather conditions and traffic volumes/types. Water is used to compact the constructed roads and maintenance of the roads. During periods of drought, water is difficult to source and depends greatly on local land holders to supply water for roads nearby. Ideally all roads within the Shire would be sealed which would extend their useful lives significantly and reduce the need for maintenance, with a small ratepayer base this is not feasible.
During prolonged periods of drought and dry conditions unsealed roads deteriorate rapidly as the moisture that binds fine particles and coarse particles are removed through wear and tear. This requires maintenance of re-grading and adding water to assist with compaction. Wear and tear may result in subgrade deterioration and defects such as pot holes, corrugates, loss of shape, rutting etc and significantly can affect driveability along affected roads. This in turn may lead to mechanical failure, increased emissions and air pollution (dust)
The objective of the trial was to identify a best practice in road construction and maintenance and implement these practices into our unsealed road strategy and update policy and procedures where required. The updated policy, procedures and strategy would identify climate resilient methods of constructing and maintaining our unsealed roads network.
Hollands Lane was chosen to be part of the trial, as it was a consistent straight road that would present typical results along its length. Research was undertaken into products and processes that may increase the useful life of unsealed roads and reduce the need for maintenance. Information and costings were sought from multiple business’ and organisations and collated in a spreadsheet. From this, products were chosen on costs, environmental performance, the ability for council to construct (no specialised equipment/staff required) and suitability to our soils.
A variety of Chemical-based Stabilisation products and price effective seals were chosen (below) ensuring a comprehensive trial with products that are cost effective and easily replicated.
- Double-Double seal
- Primary Seal
- Otta Seal
- RST Dynamic
- Terra 3000
The Project is divided into two stages.
- Stage 1 - Construction based data
- Stage 2 –Maintenance and performance based data
In the Construction stage, three factors are used to compare these treatments,
- Water Usage
- Fuel Usage
Stage 1 was finished on 21 January 2021 and the results as shown in Fig 1. In terms of price RT 20 Dynamic is the Cheapest to install, however is 5th in term of water and fuel usage.
Two factors are considered in Stage 2. They are:
- Cost -Maintenance cost
- Durability-Condition Rating for each section
The construction phase was completed in January, and the success of each treatment is yet to be determined. Early indications suggest that all treatments will improve useful life of the asset. Maintenance and long term performance will determine the best practices and products. Information was collated such as CBR, traffic type and quantity, water used, machinery used, materials used, cost, labour and weather conditions
The construction phase was completed in January, and the success of each treatment is yet to be determined. Early indications suggest that all treatments will improve useful life of the asset. Maintenance and long term performance will determine the best practices and products. Information was collated such as CBR, traffic type and quantity, water used, machinery used, materials used, cost, labour and weather conditions.
Proudly Funded by the NSW Government in association with Local Government NSW.