Background to proposed NAASRA guidelines for the provision of safety barriers.

This report discusses the background to the sections of the guide which indicate whether a guard fence is required at a particular site. It was concluded that the decision to install a safety barrier could not be based solely on likely accident rates and costs. Consequently, the guidelines are based on engineering judgement and experience. The guidelines presented here reflect different safety requirements for different road types; road types being specified by traffic volumes and design.