Historically, the extent to which nonrhizomatous and nonstoloniferous vegetation, particularly grasses, on the road shoulder contributes to the premature deterioration of road pavement by impeding the off-surface flow of water has proven, in the absence of empirical evidence, to be controversial. Anecdotal evidence has beeen used to support the need to remove such vegetation. A pilot study was conducted to determine the relationship, if any, between the presence and abundance of road-shoulder vegetation and pavement condition ratings through an attempt to reveal the existence and strength of any correlation between the variables. Besides vegetation and pavement condition factors such as cracking and raveling, a number of other variables were investigated, including average daily traffic counts at the nearest road intersection, soil factors, roadway and shoulder grade, ditch condition, and canopy cover over the roadway. Whereas the purpose of the study was to collect and analyze data testing the null hypothesis that nonrhizomatous, nonstoloniferous vegetation does not cause premature pavement deterioration by impeding the off-surface flow of water, the purpose of this paper is to stimulate further research. The results of the pilot study indicate an apparent lack of association between the presence and abundance of shoulder vegetation and pavement condition because the correlation coefficient was not statistically significant. Other factors, however, are shown to be significantly correlated with pavement condition. Therefore, the study should be expanded to account for the influence of factors not considered in the pilot study because of data gaps.
Abstract