Deflector Screen

When the moving masses of material are too large or when there is insufficient space to install a barrier structure, a well-tested solution providing protection against quantities of up to several tens of cubic metres is to use a deflector net. The installation and maintenance costs are reasonable.

Moving masses are channelled through the interception window and then guided between the nets and rock wall. Owing to the weight of the nets, boulders are slowed down between them and the wall, so that they lose both speed and energy. A simple blocking structure at the base (such as a rockfall protection screen, earthwork or gabion structure) is all that is needed to stop them.

A sufficiently strong net must be selected in accordance with these criteria (HPN netting or ANONET net, 9-15 mm in diameter of 1+4 or 1+6 ring type). The posts must be sufficiently high to provide a large enough interception window.

To ensure the safety of workers placing such nets, a layer of double-twist netting should be installed before installing the nets. In addition, this netting will make it easier to place the net (by avoiding any rock spur that might catch the rings).