In order to increase the traffic safety on German roads by means of road infrastructure measures the establishment of new design guidelines for rural roads is of great importance. The new design guidelines should be based on a new design principle: roads ought to be standardized and self-explaining. Standardization of roads means that there will be types of uniform road layouts, which can easily be distinguished. The meaning of self-explaining in this context is that roads are designed in such a way that road users can recognize subconsciously how they are expected to behave. Both targets can be reached by defining a limited number of sets of design options, taking operational aspects into account, and by defining a close relationship between these sets and the function of the road. The main point is to establish a new guidance figure in order to define the right combinations of different types and sizes of design elements. Up to now, the guidance figure for road design has been the design speed. But the design speed only defines the minimum radius of a curve with a maximum cross slope under defined circumstances. The design speed does not determine the type and width of cross sections, the type of intersection or the operation mode. Neither is there a strong relationship between the design speed and the required sight distance, the length of a straight section, the inclination or the cross slope. This is the reason why a design class, as it is called, has been defined as a new guidance figure.
Samenvatting