In many cases the rockfall protection barriers must adapt to the conditions of the terrein. One of the points that require greater attention and detail to guarantee the structural strength of the rock barriers is te deviation on lower lateral cable. In the drawing belowe you can see two typical case but not the only one. You may need to resolve deviations elevation (as in drawings) and planimetric.
Case n°1: lateral lower cable deviation
Case n°2: intermediate lower cable deviation
In many cases it is the experience of the engineer on site or installation company that allow you to solve the problem...but....
....after the Guideline ETAG027/2008, the variation of geometry of the rockfall barriers respect to the tested barrier will be guaranteed by the manufacturer with special calculation as as described in chapter 4.3:
"If for local reasons of the natural site it is necessary to have a different geometry from the test site geometry a specific design shall be provided. Forces acting in the structure should be evaluated to demonstrate the fitness for use of the falling rock protection kit. The producer, under its own responsibility, shall provide geometric tolerances in the installation book with special references to the spacing of the posts and the inclination of the main ropes".
I don't understand if the responsibility to define what forces act on the modified structure are in charge of the manufacturer or designer???
And today for my experiences I've never found a manual with described tolerances permitted for the deviation of lower/lateral cable.
Who can clarify this issue?
Thomas