From what I have seen in this thread, there are a few inconsistencies. Some BG lines may have run 9' wide sleepers. I know from experience that most of the S.A. BG lines were 8'6", 9" by 5" sleepers. The main two timbers that were used were jarrah and wandoo, which were both sourced from Western Australia.
Jarrah sleepers, they were not too bad to lift, and when we were handling them, they used to go about 75 kilograms each. Wandoo sleepers, on the other hand, they used to weigh in at about 125 - 140 kilograms each! And, that was after years of use on the lines!!!
According to a timber book that I read years ago, jarrah timber has a density rating of about 800. I am not sure what units are used to measure the density. Wandoo, on the other hand, has a density rating of 1,500 and in the book, it was recommended for use in salt water, supporting steel!!!
Wandoo sleepers, when cut, had a white to yellow colour, and were fairly knotty. We tried to machine a few sleepers for timber for a bar, but the milling machine would not accept the sleepers. Bugga!!!
When cutting the sleepers with a freshly sharpened tungsten tipped sawblade, the jarrah sleepers were cut like a knife through soft butter. The wandoo sleepers, on the other hand, it was a fight to get the sawblade to cut them. It was also very rare to find termites / white ants in the wandoo sleepers... we come to the conclusion that the timber was too hard for the termites!!!