The use of commercial cad software in snow avalanche run-out estimation

Abstract

Linear infrastructures like highways and transmission lines often pass avalanche terrain both in remote and urban areas. In some cases these areas are quite wide, measured along the lines, and the number of avalanche paths can be counted in dozens or even hundreds. Avalanche hazard assessment can be quite tedious in such areas when conventional methods like α/β are used. In 2009 the state owned Icelandic Landsnet (Icegrid) was working on a 107 km long transmission line running from the power station in Blanda river northwest Iceland to the capital of North Iceland, Akureyri. Most of the line runs along valleys with high and steep mountains. Our work was a preliminary estimation of the avalanche hazard along the route. Due to a limited timeframe set for the work it was important to find a method to deal with all these avalanche paths in an efficient way. No previous work had been carried out for this transmission line but avalanche records were known in some areas, as the transmission line partly follows the state highway. A solution based on long experience in designing roads and highways using Bentley Microstation and GEOPAK software in Iceland was chosen. The GEOPAK design software has a very flexible cross section module that allows the user to write macro programs to solve specific problems. In snow avalanche context this would be to estimate avalanche run-out at given locations. This article describes how the commercial cad software can be used in estimating multiple avalanche runouts along transmission lines, using the α/β-method. This method can speed up the tedious work at the initial stage of avalanche hazard assessment along linear structures.