Pallet ratings

Hi all I have been tasked with doing a procedure on pallet loads and ratings (which I thought was going to be easy). The more I looked into this the more question I had rather than answers. - Different load ratings on different styles of pallets - My operations are very remote and the access roads can be very rough so are shock loads calculated into the ratings and if so what is the safety factor. - All pallets were rated as new so what is the metric you should be using for older pallets and how are they rated?? Does anyone know if there is an Australian standard which covers this information?? Or is there anyone in Procurious world that understands the science behind pallet construction?? Any help would be greatly appreciated Thanks heaps