<p>We got to cross a bridge because we followed a red flag (a vessel that cannot stop because it's carrying dangerous cargo) and the bridge had to open for it which it otherwise would not have for us.  This is the marine analog of chasing amulances, when all lights turn green.
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<a rel="nofollow" class="external text" href="https://www.flickr.com/people/68877611@N00">Peretz Partensky</a> from San Francisco, USA
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<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/ifl/7315917944/">Red Flag coming through</a>