🔍 Key Concepts

• U.S. Army Corps of Engineers lock signal lights used on inland rivers • Difference between steady vs. flashing light indications • Standard meanings of red, green, and amber in lock/traffic control situations

💭 Think About

• Think about how colors are typically used: which color usually means "proceed," which means "stop," and which means "caution" in navigation and traffic control? • How does a flashing light usually differ in meaning from a steady light in control systems (locks, bridges, traffic signals)? • Which light signal would logically be used to clearly tell multiple approaching vessels that the chamber is ready and you may enter now?

✅ Before You Answer

• Verify how green vs. red are normally used for permission vs. prohibition at locks and bridges. • Check what role amber (yellow) typically plays: is it a full permission, a warning/stand-by, or something else? • Consider whether "flashing" or "steady" would be more appropriate to draw attention to a "you may enter" indication for an approaching tow or vessel.