weird highway sign i saw tonight

i live in saskatoon saskatchewan canada.

tonight my brother and i were driving on the main freeway, they are doing construction on some sort of asia-pacific gateway.

they put up the new highway signs. you know the big ones that are over the road and tell you which way to turn. one of the new symbols we saw (next to the trans canada/yellowhead) was a sign that had a captial M encased in what looked like two pillars on either side and a triangle on top. kind of like what you would see in front of the entrance of a government building. under that symbol was a closed sign. so this is the new gateway sign i presume, as the new roads aren't completed yet but you can still get on the other roads.

does anyone know what this means?