The influence of roadside vegetation on pavement roughness affected by alluvial expansive soil deposits in Victoria, Australia

This research has investigated the influence of roadside vegetation on pavement roughness progression rates. For this purpose, a rural highway located in North West region of Victoria was selected as a potential site that contained moderate to highly expansive sub-grades and semi-arid climate conditions. Roughness data was retrieved from VicRoads and roadside vegetation data was collected using satellite and street view imageries. The roughness data (both in IRI and waveband roughness indices) were analyzed against roadside vegetation data to understand the inherent relationship between these variables. Roughness progression rate models were developed for all waveband indices to better understand the tree contribution at various roughness wavelengths. Furthermore, a safe tree plantation design guideline has been proposed which can reduce the risk of deterioration relevant to the presence of trees in road reserve. Finally, a tree proximity ratio and design charts have been developed which can used as a design standard for roadside tree plantation strategies, and help in asset management and cost reduction in maintenance and rehabilitation strategies.