Snow clearing by manual labour

Backblip 3
This huge area these guys are clearing is just one side of the roof of the local congress hall. They've been at it for three days now and perhaps the end is now in sight.
The roof isn't flat but it's not got much of a slope on it. I wonder - did the architect consider the fact it snows up here...
(To be fair to architects it is, depending on who you ask, 30 - 100 years since so much snow fell in such a short time.)
The plastic they have laid on the roof means the snow slides off from where they are digging, rather than having to be carried to the edge. I'll have to try that at home when the need arises.