The message is correct and polite. There are no childish symbols, because you are assumed to be literate. In this case, there is an easy expectation that you know what an "expansion joint" is. I get simple pleasure from North American signage. I do wonder why the sign is so temporary, when the expansion joint is so permanent though.
I didn't take a photograph but another Canadian sign I saw was rather amusing. Over the urinals at the Vancouver Convention Center are stickers warning (in polite, good English and - thank goodness - again without illustrations) that the water used to flush them is recycled and unfit for drinking. Hmm.
Beggars in Canada are also polite and articulate. As I had a pocket full of coins that would only otherwise rattle around in a drawer for years I handed them to a chap who asked gently for the price of a coffee. His thanks were brief, sincere and accompanied by best wishes to me and my family.
Thanks to British Airways (an airline I have told my secretary never to book me on when there is a reasonable alternative) I have an extra few hours in Vancouver. Had I known, I could have gone for a walk, rather than wasting time in the departure lounge. I can already feel British mediocrity reaching out to me across the width of one continent and one ocean. How sad.