Construction alternatives for drainage when reconstructing motorways

Arrangements for surface and for the harmless di.scharee of saepaee water are dealt with. A differentiated analvsis of the long-term behaviour of the solutions adcp ced is g~ven, depending on the substantially different soils occuring as road foundation and subgrade. In connection with surface drainage the drainage arrangements at the inner edges of curves are more particularly considered. Also, the surface configuration of the formation, the longitudinal drainage pipelines with the monitoring appurtenances, and the outfalls in~o natural watercourses for the discharge of seepage water are assessed. Reconstruction of the motorways in the German Democratic Republic is carried out largely by overlay with unreinforced concrete. The supplementary modifications to the drainage installations are simple if the foundation soil is non-cohesive. With cohesive soil, changes and additions are needed to ensure the functional dependability, taking account of the conditions imposed by the application of slip-forming. Suggested solutions are presented. For those sections to be reconstructed by renewal of practically the whole of the pavement structure it is essential to adopt drainage systems of proven reliability and to replace inadequate ones by better solutions. Care must be taken to provide suitable connections to the drainage arrangements in overlay sections of motorway, because the sections reconstructed by substantial renewal of the whole pavement structure (governed by the levels of bridge works) are often only about 600 m long. Favourable solutions are possible for the drainage systems on new motorways, taking due account of the requirements of slip-forming technology.