Regards 2 drawbridges in Puget Sound that I am familiar with -- Ballard ( Bridge 4 ) and Chambers Creek ( both BNSF ), they are manned 24 / 7 -- AFAIK. Approaching Marine Traffic simply presents itself within sight of the Bridgetender. Bridgetender then checks with Dispatcher and opens bridge for marine traffic when told to by Dispatcher. Most marine traffic at the 2 bridges consists of pleasure craft,( with a few commercial fishing trawlers in season at Ballard ), and so will often have to wait for BNSF / Amtrak / Sounder trains to pass by first. Marine traffic at Ballard is also subject to transit through the nearby Ballard Locks, which often results in a rush of boats through the Drawbridge.