First Avenue Bridge
Bascule drawbridgeFirst Avenue Bridge is a bascule drawbridge with 22 ft closed, opening to unrestricted height.
Clearances are from NOAA charts, referenced to mean high water. Actual clearance is lower at higher tides and storm surge. Always confirm against your vessel's air draft and the posted clearance gauge before transiting.
How to request an opening
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.
Source: US Coast Guard drawbridge regulations, 33 CFR 117.1041 (Duwamish Waterway). Confirm before transiting.
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Frequently asked
What is the clearance under First Avenue Bridge?+
First Avenue Bridge is a bascule drawbridge. Its closed vertical clearance is about 22 ft, and it opens to unrestricted height. Heights are referenced to mean high water (MHW).
How do I get First Avenue Bridge to open?+
Contact the bridge tender on VHF-FM Channel 13, or sound the required signal. Operating schedule: 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 vesse
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