MileCheckHow do boats ask a drawbridge to open?
With a horn or a radio call. The federal signal is one prolonged blast, four to six seconds, followed within three seconds by one short blast. If the bridge can open right away, the tender answers with the same signal. If it can't, the tender answers with five short blasts.
The rule
Federal drawbridge rules are in 33 CFR 117. Section 117.15 sets the sound signal, a visual signal for boats without a horn, and allows a request by radiotelephone. A boat keeps signaling until the tender acknowledges (33 CFR 117.15, checked November 5, 2026).
When a bridge can say no
Each bridge can have its own exceptions. In Seattle, the Ballard, Fremont and University bridges need not open for most boats on weekdays from 7 to 9 a.m. and 4 to 6 p.m. From 11 p.m. to 7 a.m. they open with an hour's notice to the Fremont Bridge tender. See every Seattle bridge's rule.
What drivers see
When a boat signals, the tender stops traffic, lowers the gates and lifts the span. Seattle publishes live status for five bridges. The Seattle Drawbridges page shows which one is up.
Is the bridge up right now?
Seattle Drawbridges shows live up or down status for the five Seattle bridges the city reports, with each bridge's opening rule.
Questions, answered
Can the tender make a boat wait?
Some rules let the tender hold a lift for a few minutes to clear road traffic. In Seattle it is up to 10 minutes, except for boats towing.
When does a sailboat ask for an opening?
When it can't pass under the closed bridge. The bridge's own operating rules still apply.