Researchers optimize use of cable cranes in forestry work

Forestry services are using cable cranes more and more for forest maintenance. A team at the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) and the Swiss Federal Institute of Technology Zurich (ETH) based in the Greater Zurich Area have developed new software to properly prepare their use. This means that the cable roads can be planned optimally according to a press release from the WSL.

Forestry services use heavy machinery such as forwarders for work in forests, but these are not suited for steep terrain. Another difficulty for these machines mentioned in the WSL report is presented by areas in the lowlands where care is taken to protect sensitive soils. Cable cranes are an alternative for both instances: logs are transported to a collection point via a carriage that rolls along a suspension rope. According to the report, these procedures are used in around a quarter of Swiss forests today.

In order for cable roads to be run safely and efficiently, the equipment must be carefully planned to suit the terrain conditions, which includes the positioning of supports. Leo Bont, a WSL researcher working at the ETH, addressed this in his thesis. He used an old method developed by Professor Otto Zweifel at the ETH in the 1960s. The theoretical foundations from the doctoral thesis then underwent practical testing in the forest within the research project “New Foundations for Efficient Cable Road Design”. Zweifel’s calculation method led to accurate predictions of cable sag and tensile forces.

The result of the work from the WSL and ETH researchers is an open-source software tool (QGIS plugin) called Seilaplan (a portmanteau of Seilkran [cable crane] layout planner). In addition to cable roads, it also calculates the optimal support positions for the cable. 

According to the WSL, forestry companies and authorities even beyond the borders of Switzerland are showing a great deal of interest in the results of the field tests and freely accessible QGIS plugin, Seilaplan.