This document deals with the design of main roads outside of urban areas and concerns not only the improvement of the existing network but also the construction of new roads. lt deals neither with roads having two carriageways, limited access and grade separated junctions, nor with the urban road network. Nearly all national roads and major local roads (except for motorways and limited access roads with dual carriageways) are concerned by this document. However, this text can only be regarded as a recommendation if the road authority decides not to apply it on its network. The present document also concerns by-passes of built-up areas. The term « by-pass » means a non urban road around a built-up area (generally of small or medium size), that mainly ensures the flow of through traffic. However, this document does not apply to ring-roads to urban areas whose main role is to ensure a liaison between the various districts of the built up area and not only the flow of through traffic. Ring roads must thus be considered as urban roads which may belong to the urban limited access road network. Cross-town links are considered as urban roads irrespective of the size of the urban zone, even if they have particular characteristics the relevant texts concerning urban roads should be referred to (see bibliography, subject « cross-town links, urban roads ») However, the necessary discussion concerning the overlap between rural and urban areas, the crossing of villages and hamlets, as well as conunents conceming the crossing of small urban areas, are put together in the same chapter. The case of roads located in difficult relief is also the subject of a separate chapter. This document contains the fundamental technical rules for the general conception and the geometric design of the road, as well as the general principles that the project designer must follow. However, where the detailed technical measures are covered by specialised documents and recommendations they are not discussed. In the same way, the necessary preliminary design and the design procedure are not fully treated, although they are mentioned, particularly, in the first chapter. For all these elements, the text refers to other publications and their references are given in the bibliography.
Samenvatting