A new Austroads study has investigated the maintenance impacts of grader blading and surface re-sheeting on unsealed roads.

The two-year study assembled and analysed roughness data collected by Cassowary Coast Regional Council in Queensland, Blayney Shire Council in New South Wales and Moorabool Shire Council in central Victoria.

The purpose was to expand the current works effects (WE) models to cover a wider range of traffic and climatic conditions and to validate the existing unsealed road roughness deterioration (RD) model.

Austroads developed WE models for light blading, medium blading and granular re-sheeting maintenance works and a RD model was developed for roughness progression between maintenance activities.

The WE models are typically a function of the roughness before maintenance, the timing of the roughness measurements before and after maintenance, and annual precipitation. Traffic was not found to be a statistically significant variable.

The WE models for the medium blading and re-sheeting predicted similar impacts on the roughness before maintenance, despite the differences in maintenance effort. 

The RD roughness deterioration model is a major function of annual precipitation, time and the roughness before maintenance. Traffic was also not found to be a statistically significant variable in the RD model, which Austroads says may be a characteristic of the three road agencies in the study.

Austroads says the suggested modifications to the RD and WE models can assist local government asset managers in their management of unsealed roads,

Studies such as this, which can assist local government asset managers with the management of unsealed roads, are crucial – 63% of Australia’s 907,520km of roads are unsealed, according to the Department of Infrastructure and Regional Development.

Austroads says it is expected the models could be adapted to the varying local conditions of unsealed roads in other locations. 

Read the full report here.