Ten Years of Digital Rockfall-Protection Net Operation at Ovella: Cost-Efficient Construction and Maintenance Through Continuous Monitoring and Alarming

Summary

Abstract

In the last decade, a hydropower plant project was realized in Ovella, at the Austrian and Swiss border. The construction site lays just below the mighty Kitzmaiss-Wall which is prone to rockfall. Therefore, 1.2km of rockfall protection nets were installed to protect the workers and the hydropower plant from falling rocks. Geoprevent installed an alarm system to detect the rockfall events and impacts into these nets in real-time with over 100 motion sensors that are mounted on the nets. The status of all sensors is visible in the Geoprevent data portal at any time. The Geoprevent alarming system triggers an alarm in real-time (2-3 seconds). In case of impact, the predetermined breaking points of the sensors break, and an alarm is triggered. The motion sensors communicate with a basis station on the Swiss side of the Inn river to transmit the alarm. During the active construction phase, the status beacon on the construction site continuously showed the status of the system. It showed a green light, if the system was running without any detection but switched to an orange light in case of a small respectively a red light in case of a large rockfall event. In the case of a large event, additional evacuation sirens were turning on to give an acoustic and visual alarming signal for the workers. Further, the workers and responsible people were immediately informed via SMS as well. Now, after more than ten years of operation, this system provides a unique long-term dataset which helps to gain knowledge about the maintenance needs of the protection nets. This work shows how continuous monitoring of the rockfall nets has improved the safety of the workers and reduced the maintenance costs.