Managing trees in road reserves for road safety

Abstract

Paper presented at the 31st Annual Southern African Transport Conference 9-12 July 2012 "Getting Southern Africa to Work", CSIR International Convention Centre, Pretoria, South Africa.

Trees are planted or allowed to grow in road reserves for reasons such as aesthetics, glare screens, control of marginal access or median crossings and shade for rest areas. International research on the role of trees in road safety confirms that trees do pose a risk and positive policies to manage trees must be formulated and executed. South African provincial road authorities do not have comprehensive policies on trees. Some have policies with respect to the landscaping of road reserves, including planting of trees, at developments along the road. The road reserve must be managed to provide reasonable safety where vehicles run-off the road or hit objects on the roadway. This is in line with the philosophy of a forgiving highway. Some aspects of the management of highway trees are presented from international research. Trees must be classified with respect to factors including the distance from the road edge and possibility of falling on the road. A methodology to assess risk and manage trees is proposed. It is advised that road authorities adopt policies with respect to trees and develop strategies and procedures to manage trees to insure road safety, by maintaining clear zones (recovery areas) free of trees.