🔍 Key Concepts

• Fixed bridge lighting requirements in inland waters • Meaning of red vs green lights on bridge spans • How channel edges or safe passage areas are marked at night

💭 Think About

• Think about what information mariners most need when passing under a low, single-span fixed bridge at night: position of the safe water, or instructions to stop? • Ask yourself how red and green are normally used together on aids to navigation (like buoys and ranges). How might that pattern be applied to a bridge opening? • Consider whether a single-span fixed bridge is something that ‘opens’ or has opposing traffic like a road tunnel, or if it simply has a navigable channel beneath it that must be marked.

✅ Before You Answer

• Verify in the Navigation Rules and bridge-lighting guidance how channel limits under bridges are marked at night • Check whether red lights alone are normally used as a stop signal for vessels, or for marking one side of a channel • Confirm whether a single-span fixed bridge actually opens or controls traffic, or if lights mainly show where it is safe to pass