Heavy freight vehicle pavement performance study published
A seven-year study aimed at improving understanding of pavement surface failures caused by heavy freight vehicles has been published.
The Austroads project focused on gaining an improved understanding of the failure mechanisms that are particular to the pavement surfacing layer – as distinct from the structural layer – that may be caused by changing configurations and loadings of freight vehicles.
The project led to the development of the Surface Wear Tester (SWT), which was demonstrated as capable of applying sufficiently high levels of horizontal force to a surfacing (with emphasis on sprayed seal surfacings) to allow comparative testing to be undertaken for a range of binder types and operating conditions. Possible amendments to the current prescriptive performance based standard for horizontal load are discussed. Avenues for further work are presented.
Among the findings:
a horizontal force of 12kN per (standard trailer) tyre for surfaces in the range of 25-50 degrees celcius represented a threshold below which all surfaces showed good resistance to wear;
Temperature is an important factor in pavement wear; when the surface temperature was below 40 degrees, there was less damage; and,
surfacings containing PMB proved more resistant to wear than surfacings containing Class 170 bitumen.
There is no way of preventing vehicles from applying increased levels of horizontal force, and the report suggests infrastructure solutions are key to reducing or withstanding pavement wear.
The report “Heavy Vehicle Horizontal Stresses and Pavement Surface Performance’’ can be found at the Austroads website.