Proper road alignment has a positive effect on driver behavior and road safety. There have been many researches about the combination of horizontal and vertical alignment, especially for rural highways. Unfortunately, the results are not transferable to motorways for the reason that motorways are characterized by larger elements of the alignment and wider cross-sections. Consequently the preparation of Chapter 5.4 'Three-dimensional alignment' of the Guidelines for the Design of Motorways (RAA 2008) is based primarily on experiences and agreements. Furthermore, there was no method for design, evaluation and verification of the three-dimensional alignment of motorways based on qualitative and quantitative parameters. Such a method exists for rural roads. It is cited in 'References on the Visualization of the Design of Rural Roads (H ViSt)'. However, it is not transferable to motorways, too. The aim of the project was a comprehensive investigation of the three-dimensional alignment of motorways. Moreover, the RAA and the H ViSt content requirements should be given on the base of the results. Therefore, measurable values, concerning safetyrelevant and optical deficits of three-dimensional alignment, were analyzed. Limit values, based on accident occurrence on selected routes and virtual routes, were derived. The results showed that optical deficits of motorways three-dimensional alignment exists, even when the horizontal and vertical alignment of motorways are designed according to the RAA. However the deficits are not safety-relevant. Furthermore, Chapter 5.4 'Three-dimensional alignment' of the RAA must be revised. In Chapter 5.4, the verification method of motorways threedimensional alignment can be adequately described. So there must be no revision of Chapter 5 'Method for verification of three-dimensional alignment' of the H ViSt. Only supplementary comments are necessary, if the instructions are relevant for motorways or not. A text proposal for Chapter 5.4 'Three-dimensional alignment' of the RAA was prepared. It contains references to the instructions on visualization (Chapter 2, Chapter 3, Chapter 4) and on how to use the sight shade band (Chapter 5.3.2) of the H ViSt. These Chapters can also be applied to the motorways. The text proposal shall be the base for discussion to update the RAA in the relevant Working Committee 2.1 'Motorways'. (Author/publisher)
Samenvatting