Brief notes on designing protection systems against rocks falling down slopes

In many cliff-line situations it is not feasible to carry out comprehensive stabilisation of all slabs and blocks of rock that may slide or topple from the face. It is often necessary to design protection systems for whatever structure happens to be in the path of possible falling boulders. In order to do so it is necessary to estimate the energy of the boulders that may fall down the slope and then to design a suitable structure that may either absorb or redirect this energy. This note sets out a procedure for carrying out this design process. However, it must be emphasised that the approach set out contains much subjective judgement on the part of the author although wherever possible the procedures have been checked against actual experience and recorded data (scarce though this is).