The dimensions of, and information for, the barrow cart she has are:
Overall length: 9' 11"
Width : 46"
Height: 7' 6 1/4 "
It has 270º steering.
It seems the barrows were made of Ash, a hardwood, known for its elasticity and resilience; I'm assuming that the Tappy barrows would have been made in the same way using the same techniques and wood type.
From the information given in the film, it took about a fortnight to make a hand barrow; I wonder how long it took to make a wagon barrow?
The video in the link below was slightly temperamental in starting, this may be due to my computer.