Roads that are safe in all weathers are a prerequisite of modern society, and large amounts of money have to be spent, especially in winter, by highway authorities to make travel safe. Climatic factors like fog frequency have to be taken into account in planning the route that a road will follow. The operation and maintenance of the road network requires that weather information be taken into account if measures like preventative salting and top dressing are to be successfully carried out. Particularly in the field of winter maintenance of highways a range of new technology has recently become available that is revolutionising the work of the highway engineer. Ice detection systems, thermal mapping and weather radars are being introduced or considered by many authorities, in the UK, Europe and North America. There is intense interest in the performance, reliability and cost-benefits to be gained from employing the new technology. Meanwhile research shows that weather is often a contributary cause of many road accidents, and although motoring accidents in fog, often referred to in the media as "motorway madness", make the headlines, more commonplace events like heavy rain and ice exact a continuing toll of injuries. Highway Meteorology is a result of the increasing cooperation between meteorologists and highway engineers and brings together an overview of trends and developments.