Hi Dave
At a guess I would say those large posts are about 30/32ft in height and the Heads approx 2ft across - Diameter looks about 4/5" with the base diameter between 6/8" - this takes into account the Increased height - Only my thoughts of course, and I may be completely wrong
The diameter for new standard lamp posts in my area is 3" and the larger diameter at the bottom is 5", and stcks out of the ground about 3ft 6".
Hope this helps.
Cheers.
Bob.