33 CFR § 117.1041 - Duwamish Waterway.
(a) The draws of each bridge across the Duwamish Waterway shall open on signal, except as follows:
(1) From Monday through Friday, except all Federal holidays but Columbus Day, the draws of the First Avenue South Bridges, mile 2.5, need not be opened for the passage of vessels from 6 a.m. to 9 a.m. and from 3 p.m. to 6 p.m., except: The draws shall open at any time for a vessel of 5000 gross tons and over, a vessel towing a vessel of 5000 gross tons and over, and a vessel proceeding to pick up for towing a vessel of 5000 gross tons and over.
(2) The draw of the South Park Bridge, mile 3.8, need not be opened for the passage of vessels from 6:30 a.m. to 8:30 a.m. and from 3:30 p.m. to 5:30 p.m., Monday through Friday except, Federal holidays, other than Columbus Day.
(3) Between the hours of 11 p.m. and 7 a.m., Monday through Sunday, the South Park Bridge shall open if at least a 12 hour notice is given by telephone or VHF radio to the drawtender at the South Park Bridge. If emergency responders require a bridge opening between 11 p.m. and 7 a.m., the South Park Bridge shall open within 45 minutes from initial notification to the Fremont Bridge operator. Vessels engaged in sea-trials or dredging activities may request a standby drawtender to open the bridge, on demand, during sea-trials and/or dredging operations, if at least a 24 hour notice is given to the South Park Bridge drawtender.
(b) The following bridges shall open on the specified signals:
(2) Burlington Northern Santa Fe railroad bridge, mile 0.4, one prolonged blast followed quickly by one short blast.
(3) First Avenue South bridge, mile 2.5, three prolonged blasts.
(4) South Park highway bridge, mile 3.8, one prolonged blast followed quickly by one short blast and one prolonged blast.
(c) When fog prevails by day or by night, the drawtender of bridges listed in this section, after giving the acknowledging signal to open, shall toll a bell continuously during the approach and passage of vessels.