Main objective of work-package 3 of Ripcord-lserest was to collect information on best practices concerning the design of self-explaining and forgiving roads. In order to gain an overview on existing practises on road categorisation and the layout of typical rural roads a questionnaire survey had been launched. The results showed that the design of self-explaining roads is not widely spread in Europe although more and more countries include ideas which are also applied in the few concepts of selfexplaining roads into their practice of road categorisation and road design. The survey revealed that mainly three countries have already implemented such concepts or at least started the implementation. Based on the three practical examples and research results, a general recommendation for the design of self-explaining roads has been developed, which will be described in the following chapters. The concept of self-explaining roads, bases on the idea that roads with certain design elements or equipment raise certain expectations in road users regarding their own driving behaviour and the attitude of other road users and thus induce appropriate speed or steering manoeuvres. A self-explaining road is therefore a road designed and built in such a way as to induce adequate behaviour. A perfectly designed self-explaining road is able to support motorists in their driving task and does in this way reduce the necessity of local speed limits or warning signs. But the selfexplaining road concept is not only intended to influence driving behaviour but also should provide a safe road design in itself. For that reason self-explaining roads are built and operated according to the needs of safe road traffic. Another major issue of the work of work-package 3 was to collect information on road design elements which help to reduce the number and consequences of head-on collisions and run-off-the-road accidents, constitute the main part of the fatal road accidents on rural roads. Apart from general design regulations which are already considered in most national road design guidelines and which are described in RiPCORD-iSEREST Report D3.2, the most promising design and operational aspects are included in the concept of self-explaining roads. Since also a perfectly designed road cannot prevent all accidents, its roadsides have to be safe in order to avoid serious consequences once a car runs off the road. Crashes with roadside obstacles usually have most severe consequences. Therefore roadsides have to be kept free of obstacles like poles, trees and structures or these obstacles have to be guarded by guard rails. Basic recommendations on the design of safe roadsides are also given in the following chapters. (Author/publisher)
Abstract