Hi Rud,
Thanks for your comprehensive reply, it is inevitably the case we are left with probabilities.

It would seem highly likely it was a cross, Jesus was impaled on...many others were impaled by this method by the Romans. Also there is a strong like-hood due to weight considerations, if the wood was a slow growing hardwood, like olive, he carried only the horizontal cross member to Calvary.
I had an apple tree cut down in my garden a few years ago and I found it difficult to lift a section just over a metre long by c.110cms in diameter...Olive wood is c.10% more dense.
regards
Derek