This is a great video by Vermont DOT that describes how scaling is used as part of their mitigation efforts for rockfall. If you have never seen how high scaling works, this gives you a good perspective. Scalers use ropes to access the slope and work from the top down to test rocks with prybars and other tools to see if they are loose, bringing them down if they are. They also use airbags, pneumatic “pillows” that start flat and can slide into cracks and joints and be inflated using compressed air to push rocks off the slope.
The Colorado Geologic Survey has a very comprehensive overview of the geologic hazard of rockfall in all its many forms in their latest issue of RockTalk newsletter. The entire 24-page newsletter is devoted to various aspects of the problem, mitigation options and case studies all with excellent photos. I highly recommend that you check it out. Click through for the link. (Photo by CGS)