COLLECTION AND USE OF WEATHER DATA IN MOUNTAIN ROAD PLANNING

In winter, drifting snow causes maintenance and traffic problems, the main ones being snow cover on the roads, poor visibility, the main ones being snow cover on roads, poor event of a crisis. Dominant factors to be considered at the planning stage in order to minimize these problems are, wind velocities, wind directions, precipitation, average snow depths and snow distribution in the area under consideration. Regarding wind velocities the author concludes from observations on a mountain road in Norway that - driving in convoys is necessary with wind velocities of 11 metres per second on days when snow is falling, and 15 metres per second on days with no snowfall - visibility is reduced as the angle between the wind direction and the road increases - visibility is increased when the road is constructed on a continuous embankment - snow fences help to improve visibility for the processing of wind observations, it is proposed that each observation involving the same wind direction be combined through a formula to a weighted value. Plotting these weighted values on a vector diagram will indicate the most dangerous wind direction as regards snow clearing problems. Snow distribution may be mapped using measuring poles, botanical surveying, aerial photography and aerial surveying. The most important information obtained from snow measurements is - the drift forming winds - the natural erosion and sedimentation zones - average snow depths and anticipated maximum depths - sufficient data to be able to select the most suitable cross section - suitable location of snow fences. /TRRL/