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Show still had the original survey and if the statistics had been carried forward to the present, we would be close to a century- old avalanche cadaster, which would provide an outstanding foundation for avalanche zone planning. The two works of Coaz are interesting and valuable mines of information. Unfortunately, the accompanying avalanche map of the Swiss Alps to a scale of 1: 250,000, even though a great achievement at the time, is not adequate for executing avalanche zoning plans. The original surveys in scales of 1: 50,000, 1: 25,000 and 1: 100,000 cannot be located and were never continued. Another start was made following the avalanche winter of 1950/ 51- The Swiss Federal Institute for Snow and Avalanche Research ( SLF Institute) began in 1955 the survey to build a new Swiss avalanche cadaster. In 1962 the cooperative work of the SLF Institute and the cantonal forest services was newly organized and the previously limited work was intensified. It became necessary to train the needed specialists, not only for mapping avalanche areas, but also to introduce the representatives of local governments to their new responsibilities. The Federal Forest Inspectorate therefore directed the SLF Institute to give courses for people working on avalanche zone planning. The first course of this kind was given on 8- 9 November 1962 in Davos. It was attended by 27 participants from all the mountain cantons except Schwyz and Obwalden. Representatives of local government and building departments, forest engineers, foresters, civil and cultivation engineers as well as a representative of an insurance dealing with damage caused by natural elements were among the participants. A second course was given 10- 12 April 1967- V/ hile the first course was given to clarify questions on technical, administrative and legal aspects of avalanche zoning, the second course concentrated on mapping. For this reason, almost all of the 38 participants were forest service representatives, among whom were four Austrians. The Working Group for avalanche defenses, a dozen competent forest engineers working on avalanche control structures, was also interested in the problem of avalanche zone planning. The first attempt at planning avalanche zoning was documented by the SLF Institute in regard to an extension and alinement plan for the settlement of Wengen on 30 September I960. For the first time, problems dealing with the delimitation of avalanche- safe and avalanche- dangerous areas were discussed. Until 1968, most of the solutions then proposed were incorporated in more or less unchanged form in all new plannings. Even then it was obvious that an unquestionable separation of safe and dangerous areas could not be achieved. It became necessary to introduce a zone of transition between areas often proven to be swept by avalanches and areas proven to be safe from them. This zone of transition could not be considered totally safe from avalanche danger; however, the danger represented was so small that there was no justification for prohibiting construction in these areas. It became common practice to determine three zones. In definite avalanche areas, construction was prohibited and they were marked on maps in red color. The red zone was followed by a blue zone. In these areas, prohibition of construction was not justified; however, the possibility of danger was not excluded. An area that was definitely without danger from avalanches was designated as a white zone. The blue zone had in addition the special |
