A major challenge facing road agencies is the increasing shortage of quality quarried materials and natural gravels for road construction and maintenance, according to a report published by Austroads.
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The Appropriate Use of Marginal and Non-standard materials in Road Construction and Maintenance report addresses concerns associated with finite resources and current sources being exhausted.

"Gravel quarry products are being transported over longer distances, resulting in escalating costs for road construction and maintenance," Austroads said in a statement.

"Some agencies are now paying for access to previously-free materials. This problem has been exacerbated by the trend towards tighter environmental legislation, quarry operation legislation, and land access requirements, which are adding to the costs and limiting the opportunity to commission new quarries and open new gravel pits.

"The report concludes that considerable evidence exists, both nationally and internationally, that supports the wider use of marginal and non-standard road pavement materials in sealed roads. Examples of case studies from both national and international sources are offered to support this view.

"It also identifies evidence from studies of unsealed roads, which demonstrate the effective selection of unsealed road wearing course materials, and the benefits of good-quality construction and maintenance practices.

"The report provides the basis for the use of marginal and non-standard materials in sealed roads and considers the factors affecting performance. It includes national and international case studies, which provide supporting evidence of the successful use of marginal materials. 

"Increased focus on the quality of design, materials testing, and construction is seen as a pre-requisite to optimise the use of marginal and non-standard materials. The project findings support the wider use of preliminary materials assessment techniques and the report proposes a materials assessment protocol for low volume roads." 

Earlier this month, Austroads commented on a new national scheme under development to ensure the people who design, install, and maintain road safety barriers on Australia's and New Zealand's road networks are appropriately trained.