Monitoring systems have been installed at Grimselpass near Innerkirchen in the Berner Oberland, Switzerland by ALPUG, an alpine natural hazards research organization. The mountain pass road, a busy tourist route in the summer, lies in the path of potential rock falls. The site consists of two enormous vertical rock plates, roughly 200 m high, with ever-widening cracks at the back. The cracks are opening at a rate of up to 1 mm per day and are already more than 3 m wide. To monitor the rock movement, two Campbell Scientific data loggers are connected by a radio modem to the traffic lights on the main road. If there is a significant increase in the opening of the crack, or the control wires break, an alarm is sent to the lights within 1 second. It is estimated that it takes 30 seconds for falling rocks to hit the main road, so this allows for the lights to stop the traffic going through to the danger area.

Case Study Summary


Monitoring the movement of a monstrous wall of rock


Grimselpass near Innerkirchen in the Berner Oberland, Switzerland


Campbell Scientific Ltd.

Participating Organisations


Measured Parameters

Rock movement

Controlled Devices

Traffic signal (to prevent passing motorists from entering an active rockfall area)