I'm not sure if this has been discussed before, but, having escaped from the clutches of the Train Man Senior ( nice to see him back in action ), I looked into Eason's and treated myself to a copy of Father Browne's Laois - on page 108 is a most interesting picture, a turf train at Portarlington during the Emergency. The picture in the book is from the footbridge and clearly shows the first five "wagons" of the train. They are, in fact, converted passenger carriages, With planks fitted inside the windows and loading doors roughly made from planks, too. The roofs have been removed and they are filled with turf right up to the roof-line.
I can't find the actual picture online, but this small image is probably of the same ( or similar ) train.
You can just make out the sods of turf where the roofs should be.
http://fatherbrowne.com/