A Policy Recommendation for the Reduction of Tree Crashes

Trees contribute to the aesthetics of roadways but they are also the objects struck in approximately 3,000 fatal crashes annually in the United States. While the removal of roadside trees would undoubtedly reduce the number of fatal crashes with trees, it would not provide for an acceptable aesthetic environment. Balancing the positive aesthetic contribution of trees with the negative highway safety aspects of trees should be addressed in order to maximize both safety and aesthetics where possible. Creating roadway environments that are both safe and aesthetically pleasing requires an understanding of the correlations between various highway design factors and the possibility of a tree crash. Understanding these correlations will allow public policy making agencies to develop tree placement and maintenance procedures which maximize roadside tree preservation and minimize the likelihood of tree crashes. This study determined that rural collectors are the functional classification of road most prone to tree crashes; reviewed several roadway characteristics (i.e., horizontal curve, vertical curve, speed limit, clear zone, tree density, etc.); and determined speed limit, tree density and clear zone contribute most to predicting the locations of tree crashes in Massachusetts. Using this information, a regression equation to predict tree crashes based on highway characteristics was developed and a proposed tree policy for new highway construction and reconstruction, which maximizes the preservation of existing trees and predicts safe locations for proposed tree plantings is presented. Furthermore, a procedure for implementation by maintenance personal, for assessing locations which pose potential risk was developed and is presented.