Some environmental protection measures are being adopted worldwide under very similar construction principles, such as the collecting of roadbed runoff channeled into settling and oil separator storage basins in sensitive areas. Moreover, other methods have also been tried on a limited basis, such as the use of roadside verges as an ecological flora preserve which is the trend in Belgium (Flanders) and the Netherlands. Switzerland is considering changes in its regulations, since they have noticed the lowering of its ground water table levels, due to the collection of the road bed runoff; surface water infiltration will be the preferred solution, but in special conditions, because it is considered harmless to the quality of the water table. The restrictions to the provision of water for the compaction of soils are becoming a problem in some areas and are obliging engineers to look for alternative methods of compaction. The international rise in traffic growth has led to the expansion of motorway systems particularly in North America and Europe. The capacity of existing motorways has been enhanced by the provision of additional lanes. The planning of widening works needs to take account of the special nature of an active motorway site which impose constraints on working space, access and disruption to the road user. The report provides an overview of these problems and presents the solutions offered by a variety of widening techniques. Failure of existing slopes adjacent to roadways often causes disruption to traffic; particularly in abnormal weather conditions of heavy precipitation. C12 has previously reported on the topics of techniques for evaluating landslides hazard for the study period 1991-1995. In that report, advancement of monitoring and database systems are found to be effective for further development of road slope disaster mitigation. Committee C12 decided to extend those studies and adopted the topic "risk management of existing slopes" in this period (1995-1999) to focus on utilization of monitoring techniques and database applications, through a new international survey. For the covering abstract see ITRD E118727.
Samenvatting