Roadside barriers, accident frequencies and severity.

Since the criteria for the provision of safety fences and barrier (TD 19/85 in United Kingdom) was felt to be arbitrary, and not based on the risk involved, or traffic levels, the Scottish Office commissioned the project presented. The problem was considered in three parts: (1) to establish whether barriers have an impact on accident severity; (2) to establish whether barriers have an impact frequency; and (3) to advise on criteria for the installation of barriers. Following a preliminary literature review an analysis looked at barriers in the context of road geometry and roadside features, and their impact on accident frequency and severity.