It's clearly marked, 3.8 m. I think that is a little low for most semi-trailer rigs. The driver was American and the police "suggest" maybe he didn't understand metric, but they aren't very clear on it. http://www.cbc.ca/canada/saskatchewan/story/2010/11/12/sk-bridge-hit-1011.html
It really seems like every driver needs dual signage in his cab of the current worst case dimensions of his rig and load. In many cases, this will be the trailer, not the tractor, and needs to be updated for whatever he is hauling.
