Aerial Ladder Jack Plate Cribbing
I'm looking for information regarding cribbing aerial ladder jack plates. Obviously, the reason for cribbing is to spread the transfer weight of the ladder while operating on soft ground, but does anyone know what constitutes recommended cribbing? Several points:
- NFPA requires max PSI per ground pad of 75 psi, the cribbing reduces this.
- I've been researching this and cannot find anything in NFPA standards or IFSTA training material. I remember from long ago somone was recommending wood, but can't find anything that describes what size and type of wood.
- I've seen 4x6" boards to 3/4" plywood, again no formal body that I can find says anything other than its up to the operator to ensure the aerial is being operated on ground strong enough to support operations.
- I'm looking for the science behind your recommendation or practice.
Thanks in advance. Any information or thoughts are greatly appreciated!