Relationship Between Traffic Loading and Environmental Factors and Low-Volume Road Deterioration

Abstract

Many countries use some form of road user charge model to determine how much to charge road users for using roads. It is expected that trucks would pay for most of the costs as heavy vehicles would be responsible for most of the deterioration of roads. This research documents findings that would ultimately be used for the refinement of the New Zealand road user charge models. The research was undertaken on data from the Long Term Pavement Performance programme with the specific aim of determining the relative damage caused by heavy vehicles loading alone compared to the combined effect of loading and environmental impacts. As part of the over-all research process, a cluster analysis was undertaken. The result from this analysis also emphasised the importance of drainage. The cluster analysis resulted in a recommended stratification of low volume roads on the basis of their urban/rural location, traffic loading and climatic area. This stratification could be used for a more detailed implementation of a user charge model if needed. It was determined that on similar low volume roads, an approximate 0.1mm/year higher rut rate was observed in areas that have a wetter climate in combination with sensitive in-situ soil conditions. It was also illustrated that having adequate drainage is vital for limiting environmental impacts. Roads with inadequate drainage had a rut rate 2.5 times higher than roads with the necessary provision for drainage.