Case Study

This simple and effective dust management solution is helping Logan City Council address concerns about the quality of air and roads for residents in semi-rural areas.

Client: Logan City Council
Value: Ongoing supply
Location: Wyatt Rd, Undullah
Date: October 2012

Above Image: Apart from the issues with dust, the untreated road was prone to potholing and corrugations.

Above Image: The treated road is showing some significant improvements.

Project Description

The City of Logan is located between Brisbane, Ipswich and the Gold Coast and is home to more than 280,000 residents. The Council represents a diverse community, living in areas ranging from modern housing estates to bushland acreage. The road network servicing this vital residential, commercial and industrial centre includes access to the state-controlled M1 Motorway, local arterial roads and approximately 200km of unsealed roads.

Challenges

Potholes and corrugations are a major problem on any road. While damage to pavements can be expensive for local councils to repair, local residents are often frustrated by reduced speeds, increased travel times and damage to their vehicles. Resources are often tied up in listening to, and resolving complaints. For unsealed roads, potholes lead to further health and safety implications associated with airborne dust.

Wyatt Road is an unsealed road in the semi-rural suburb of Undullah. In October 2012, this unsealed road drew the attention of the local newspaper with one resident claiming dust swept up by traffic is causing breathing difficulties and contaminating water tanks.

Logan City Council’s maintenance program for unsealed roads aims to provide safe roads for residents, calling for potholes to be repaired quickly and for dust to be minimised. On unsealed roads, this typically involves mobilising motor graders and crews to re-grade the roads two or three times per year. Recent rainfall and flooding events in the Logan area have put greater pressure on the maintenance program as more roads have suffered damage.

Investigations

While unsealed gravel roads provide economically viable access for residents in semi-rural and rural areas, they can be difficult to maintain. The key to serviceability is preserving the dry strength of gravel – as gravel gets wet, it loses its strength. Rainfall contributes to pavement deterioration by eroding the fine-grade materials and penetrating the sub-base. As water evaporates and the pavement dries, the unbound fine-grade materials become susceptible to winds and vehicles.

Spray sealing and asphalting will minimise the risk of airborne particles. This, however, puts a strain on financial resources – resources that local councils fund through rates and land taxes.

Specialist equipment and crews are also required to handle these elevated temperature products.

Solution

Logan City Council determined DustBloc®, a modified bitumen emulsion incorporating additives to assist with absorbsion into road base materials, as a viable alternative.

  • DustBloc is diluted in water and sprayed directly onto unsealed surfaces using conventional water trucks. As the water evaporates, the bitumen film that remains binds fine-grade materials and repels moisture.
  • Estimates suggest re-grading unsealed roads two to three times per year costs around AU$6,500 per re-grade. Regular application of DustBloc eliminates re-grades and significantly reduces maintenance costs.
  • DustBloc is used at ambient temperature and can be diluted with any type of water. It does not require any specialist equipment or labour.
  • Bitumen’s water repelling and binding capabilities creates a road surface that is more weather resistant and less prone to fine-grade materials washing out during rain events.

Outcomes

Quality

Wyatt Rd was initially treated three times with a surface spray of DustBloc. While providing temporary relief from dust, Logan City Council found re-grading to 100mm and mixing DustBloc into the road material with the grader’s blade improved the materials ability to bind together.

Safety

Since Wyatt Road’s DustBloc treatment, the south east corner of Queensland has weathered significant amounts of rainfall. While the road has shown minimal signs of damage, it has far outperformed similar roads in the region that require extensive repair.

Environment

One local resident has reported that following the initial application of Dustbloc, Wyatt Road has dramatically improved and believes use of the product will reduce dust complaints. Further treatment with DustBloc has dramatically reduced the level of dust swept off the road. This means better access for residents following rain events and clearer air to breathe.