The overland transportation of dangerous substances carries with it the inherent risk of spillage. In 1997 approximately 9,6 million tons of dangerous goods were transported by road, with the major part of these goods being carried on a few major routes. Although the chances of a catastrophic environmental accident may be small, the impact from an oil spill or hazardous substance in a traffic accident can be highly detrimental to both the environment and to public health. In the event of an accident, the impact of these substances will be conditioned by the specific environmental conditions at the accident site. The University of Helsinki has carried out pioneer work on the risk classification of traffic areas based on an analysis of surface soil, groundwater and surface water condition. This risk classification can provide valuable information on the specific environmental conditions of traffic areas. The availability of this information would enable the rescue service to estimate the likely behaviour of harmful substances at specific accident sites and to decide the appropriate measures to take. The protection measures could then be focused directly on the right location, avoiding unnecessary delays and minimizing environmental damage.