OCR Text |
Show coordinated with the corresponding danger zones. This procedure will be explained with examples. Let us assume that the avalanche zoning map indicates a small and safe area, which, from the village, can only be reached by crossing dangerous avalanche slopes. This area, being safe from avalanche danger, could be used for construction purposes. However, since the access route is dangerous, a risk exists not only for the residents but also for the public. In such a case, the building authorities will declare the area unsafe, or at least a blue zone area. Or a community may have sufficient building sites, but its ski runs and ski exercise areas which, are partly located in the blue zone, are endangered by building projects. It is obvious that such conditionally dangerous areas should be more heavily taxed and zoned against construction. This should be done for two reasons. First, the risk implied for buildings will be totally eliminated and, secondly, the terrain will be preserved for skiing. Such political considerations can modify the avalanche zoning map to a certain degree. It is now necessary to incorporate these zones into land register plans of larger scales. The newer survey plans with a scale of 1: 10 ' 000 do not show property limits. However, it is necessary for the practical use of the zoning plans, that the location of every single parcel is clearly shown, relative to the different zones. The scales 1: 1,000 to 1: 5,000 are especially suitable for this purpose. Depending on how a parcel is divided by a borderline, it will be assigned to one or the other zone, according to its size and location. Now it will be possible to determine building specifications for the different zones. These will prohibit construction in zones unfit for development. Definitions, however, are necessary. For example: building restrictions could not be applied to the construction of underground structures such as water reservoirs, or to temporary buildings used only in summer. It might also be permissible to allow farm buildings such as haylofts and summer stables, which are protected by avalanche control structures. On the other hand buildings connected with big traffic or gathering of people such as hotels and schools might be excluded from the blue zone. The zone of transition, especially if it is broad, can be divided into smaller sections. This can be done by distinguishing between more and less endangered areas. It would be illogical to require building reinforcements to have the same load capacity on the edge of the " red zone" as on the edge of the " white zone." Therefore, avalanche pressure bands with ranges from 3.0 to 2.0 t/ m2, 2.0 to 1.0 t/ m2 and 1.0 to 0.0 t/ m2 can be provided. Eventually, a plan for evacuation must be drawn for the transition zone. The right to effect evacuation must also be contained in the regulations of the avalanche zoning plan. In practice the community authorities can only achieve an evacuation with the help of an Avalanche Warning Service. It has to give the technical advices. Therefore, such a communal service has to be provided necessarily for every settlement having " blue zones." As can be seen, the transition zone ( blue zone) occupies a special position. A comment must be made now, which could have already been mentioned in the chapter 22 |