33 CFR § 117.791 - Hudson River.
(a) The draws of the bridges listed in this section shall open as soon as possible at any time for the passage of the following vessels:
(1) Downbound vessels during a freshet of a height exceeding an elevation determined by the District Commander.
(2) Public vessels of the United States.
(3) Vessels of 500 tons or more.
(4) Tugs with a tow on a hawser.
(b) The draws of the bridges listed in this section shall not remain open for more than 15 minutes and may remain closed for up to 10 minutes to allow accumulated land traffic to pass.
(c) The draw of the Livingston Ave. (Amtrak) Bridge, mile 146.2 between Albany and Rensselaer, shall open on signal; except that, from April 1 through December 15, from 11:00 p.m. to 7:00 a.m., the draw shall open on signal if at least 4 hours notice is given and from December 16 through March 31, the draw shall open on signal if at least 24 hours notice is given.
(d) The draw of the Troy-Menands Bridge, mile 150.2 between Troy and Menands, need not be opened for the passage of vessels.
(e) The draw of the Troy-Green Bridge, mile 152.7, between Troy and Green Island, operates as follows:
(1) From April 1 through December 15 the draw shall open on signal if at least a twenty four hour advance notice is given by calling the number posted at the bridge.
(2) From December 16 through March 31, the draw need not open for the passage of vessel traffic.