Forgiving Roadsides Design Guide

Analyses of fatal road accidents in the European Union show that 45% are single-vehicle accidents. These accidents are primarily classified as run-off-road accidents, where the vehicle leaves the road and enters the roadside. A roadside is called unforgiving if hazardous objects such as trees are placed at an inappropriate distance from the road so that the risk of severe accidents is increased. The purpose of the 'forgiving roadside' concept is to avoid crashes of errant vehicles with potential hazards or to minimise crash consequences. CEDR has identified the design of forgiving roads as one of the top priorities in its Strategic Plan 2009–2013. For this reason, a specific team dealing with forgiving roadsides was established within CEDR's Technical Group Road Safety (TGRS). In recent years, several projects have been conducted with a view to producing guidelines to design forgiving roadsides worldwide, and several national standards have been produced. However, different approaches are often proposed. The final results of trans-national research projects, aimed at identifying harmonised solutions, are often extremely scientific but not practical and result in a lack of applicability. Based on the results of a detailed state of the art review and a study on the evaluation tools related to roadside features and an additional literature review, this activity produced a practical guide that can be applied in practice in road safety design projects thanks to interaction with road administrations and operators (through the webinars that have been organised and through the synergy with the CEDR TG Road Safety). The different interventions proposed are linked to the potential effectiveness estimated and defined in the effectiveness study and in other relevant literature in order to allow the user to perform a cost-effectiveness evaluation before planning a specific treatment. One issue has been the harmonisation of different existing standards or the identification of underlying reasons for different existing solutions for the same treatments in order to allow the user to select the optimum treatment and to properly assess its effectiveness. The roadside features for which the Forgiving roadsides design guide has been developed are: - barrier terminals, - shoulder rumble strips, - forgiving support structures for road equipment, and - shoulder width. Each feature is analysed in a separate section of the guide providing: - an introduction, - design criteria, - assessment of effectiveness, - case studies/examples, and - key references. This Forgiving roadsides design guide is a harmonised collection of best practice treatments to make roadsides forgiving. CEDR TG Road Safety recommends this guide to all practitioners working in road safety. As a complement to the core part of the guide providing guidance to the designers, Annex A provides a comprehensive overview of the state of the art in the field of forgiving roadsides and a detailed description of studies conducted as part of this project in order to evaluate the effectiveness of different roadside safety treatments.