Safety effects of road design standards

This report describes the results of a study carried out for the European Union. The report uses the safety principle that: (i) proper road design is crucial to prevent human errors in traffic; and (ii) less human errors will result in less accidents. The study contains the following parts: (1) gathering information about existing knowledge on the design of road infrastructure elements by: (a) drawing an inventory of international treaties and recommendations, with information about their legal status; and (b) drawing an inventory of national road design standards and the underlying knowledge; (2) analysing the role road safety arguments have played, when road design standards were compiled; and (3) drawing a 'best practice' for road design standards. Detailed studies were only carried out into: (i) cross-sections including medians, shoulders and verges; (ii) motorway exits and entries; (iii) curves in two-lane roads; and (iv) bicycle facilities at intersections. Preliminary considerations are given, for instance, to: the status of the standards, assumptions underlying the standards, and road classification. The study also summarizes the research methods to be used, when quantifying the relationship between road design standards, accidents and road user behaviour. The study reveals that existing national standards in Europe hardly contain information on the safety effects of the required road designs.