Apparenty in Copenhagen, they rigged up a big HGV and parked it on City Hall Square in association with a conference about heavy traffic, to show cyclist about the blind spot of the HGV.
translation; "Hi Cyclist! Try out a truck and see yourself from a new angle!"
Good Idea. It's nice to know they even think well enough of their cyclists to do that.
I go by the rule "if you can see their eyes, their eyes can see you." In the mirror or otherwise.