How long does a Seattle drawbridge stay up?

A single sailboat clears a bridge in a few minutes. A tug with a barge, a run of boats on a summer Saturday, or a bridge that lifts and holds for a second boat takes longer. Most openings are over inside 15 minutes.

The city's feed does not say when a bridge went up. MileCheck polls it every two minutes and stamps each transition itself, so the app and the bridge pages here can say "up for 9 min" instead of just up or down, and keep a log of every lift.

What makes a lift run long

A tug and tow. The tender cannot hold the bridge for traffic, and a barge moves slowly.
Boats in both directions. The bridge stays up until the canal is clear.
Montlake's hour and half-hour windows in the early afternoon bunch boats together.
Opening Day of boating season and the Ballard Locks summer traffic.

Which bridge lifts most

Fremont Bridge. It is the lowest bridge on the Ship Canal, so it lifts for boats that pass under Ballard and University without an opening. Seattle DOT has called it the most frequently opened drawbridge in the United States.

Questions

What is the longest a Seattle bridge stays up?

There is no upper limit in the rule. A tug with a tow, or several boats in a row, can hold a bridge 20 minutes or more. The app’s Now screen shows how long it has been up, live, so you can judge for yourself whether to wait.

Does the bridge have to come down for traffic?

A tender may delay the start of an opening up to 10 minutes to clear cars. Once the bridge is up it stays up until the boat is through.

Where does "up for 9 min" come from?

MileCheck stamps the moment a bridge appears as up in Seattle DOT's feed, which it reads every two minutes. The city's feed has no timestamps of its own.