In the Alte Gasse in Niederurnen, an increasing number of rockfall with consequential damage had occurred. The current official hazard map and a preliminary study (2016) showed considerable risks.
Several possible measures were examined and compared. The solution safety net proved to be the most efficient and cost-effective.
A safety net installation was specified and various framework conditions clarified. Two series of rockfall protection nets, 80 and 90 m long were recommended; 2,000 kJ nets with a height of 5.0 meters. To determine plausible anchor lengths, anchor tensile tests were carried out beforehand.