If I'm correct there aren't, I can't be sure as I've not been there yet after the work was done, the extra lanes open on Monday.
Before the works, there weren't any but the matrix signs as it was an NSL motorway and only in case of jams, roadworks, accidents the matrix signs either showed a lower limit or warned for jams by flashing and saying 50...
That may be the case but that is pretty much the only road between Rotterdam&The Hague and Utrecht, 3 big cities, I can't imagine people taking a different route as there is no proper other route.