NYACK – The first span of the new Tappan Zee Bridge will open to Rockland County-bound traffic only on Aug. 25-26.Westchester County-bound traffic will continue to use the old bridge for several months before it, too, is shifted to the first span. A Jersey barrier will be used to separate the west- and east-bound lanes.Then, Tappan Zee Constructors will demolish the old bridge and finish building the second span.