If I remember correctly, those timbers were well under 10 years old. I want to say less than 5.
We've got some in the yard that are well over 10 years old, and look pretty good. But I don;t think they'll be up to the strain of holding in the slowly-collapsing upper yard much longer.
"There is nothing in the world so permanent as a temporary emergency." - Robert A Heinlein The Moon is a Harsh Mistress