Here is statement issued MAY 4 by Tappan Zee Bridge Constructors:
To accommodate the lowering operations, the Hudson River’s main navigation channel will be temporarily closed. Times and dates of the closures are subject to change and will appear in the U.S. Coast Guard’s weekly Notice to Mariners; on the project’s Twitter feed (@NewNYBridge); and broadcast on Marine Radio Channel 22A. Tappan Zee Constructors can be contacted via Marine Radio Channel 16 for assistance. More boater safety information can be found at NewNYBridge.com/Boater. All mariners are strongly encouraged to avoid the area during the lowering of the suspended span as the navigation channel will be temporarily closed and equipment will be staged on either side of the closure area. The seasonal update to the Boater Safety information sheet is live on the New NY Bridge website and may be shared http://www.newnybridge.com/wp-content/uploads/2018/04/NNYB_FactSheet_Boater_April2018.pdf
Previous statements regarding Tappan Zee Bridge demolition
Closure of all river traffic will start at 3:00pm on May 7. By 5:00am May 8 the overnight lowering of the span is expected to be completed, and will be removed to the work area south of the bridge where it will be dismantled over the next 6 weeks.
However, again, the lowering could take up to 48 hours. Weather is certainly a wild card. A link to the draft timeline from Capt. Ian Corcorcan of the Hudson River Pilots is given below – be advised this is subject to change and was a working document shared at the recent with the Hudson River Navigation Safety and Operations Steering Committee meeting.