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The application of geosynthetics (ie geogrids) for the stabilisation of basecourses prepared with a River Run rounded gravel aggregate was investigated. Reductions in the rate of rut formation by over 50% were observed when geogrids were included either at the basecourse/sub-base interface or at half-height of the basecourse. The rate of rut formation was reduced further if a square type geogrid was used in place of a triaxial type geogrid. It was found that the basecourse rutted rapidly if the surface was not confined, due to the lack of particle interlock and surface confining stress. If the surface was confined with a thin (ie < 40mm) asphalt layer to bind together the particles in the surface, then the aggregate provided significant support and reduced rutting by over 90%, even without the addition of geosynthetic stabilisation.

This TAN clarifies issues related to the utilisation of concrete barriers to temporarily detain rockfall/slope debris.

Bylaw 2012-9 - NZ Transport Agency (speed limits on state highways) amendment bylaw March 2013.

Bylaw 2013-2 - NZ Transport Agency (speed limits on state highways) amendment bylaw May 2013.

The Transport Agency is using Greenroads® as a tool to assess the sustainability performance of high-value state highway improvement projects. Greenroads assessment and certification applies to the detailed design and construction stage of a project.

Bylaw 2013-3 - NZ Transport Agency (speed limits on state highways) amendment bylaw August 2013.

Road safety barrier accreditation scheme gets green light for safety.

These guidelines for surfacing treatment selection have been written for asset managers, surfacing engineers and pavement designers. They aim to guide the reader in the engineering decision making and processes that need to occur in selecting a road surfacing treatment.

Highways and Network Operations have launched the new Technical advice note series.