As a matter of interest, Richard, how does Tom Phillips translate that passage? (I feel sure you must have a copy of his beautiful translation to hand. I don't, unfortunately. Even my copy of "A Humument" went missing during a house move).

What a useful stimulus this thread had proved to be for me. Not only did I find a sensibly priced copy of the 4th edition of "A Humument", (already delivered) but one of the 3rd edition too. Better still was the unread, "as new" copy of Tom Phillips's illustrated translation of "Inferno", and for only £29.95 + p&p. That was a real find. It arrived today, so I can now relate that Phillips translates the passage as:
"Just halfway through this journey of our life
I reawoke to find myself inside
a dark wood, way off course, the right road lost."
Somewhat different from John Ciardi's:
"Midway in our life's journey, I went astray
from the straight road and woke to find myself
alone in dark wood."
No sign of SCGrew's "thicket" in either, however.
Henry F. Cary, however, favours "thicket" in Canto XIII, where Phillips and Ciardi opt for "trunks" and "roots" respectively.