You are upbound approaching a lock and dam...

Question 1 / 2707066636ee928f7522a1c51a519

Question 1 of 2707066636ee928f7522a1c51a519

You are upbound approaching a lock and dam and see two green lights in a vertical line. What does this indicate?

Question 1 of 27070

You are upbound approaching a lock and dam and see two green lights in a vertical line. What does this indicate?

🔍 Key Concepts

• Inland lock and dam signal lights used by the U.S. Army Corps of Engineers • Difference between lock wall markers and dam / weir navigation markers • Meaning of vertical green lights versus red or amber in lock approaches

💭 Think About

• Think about what information two GREEN lights in a vertical line are trying to give you as you approach: are they marking a wall, a work-in-progress, or a safe passage? • Ask yourself: which of these options would most logically need a clear, positive "you may proceed / this is the channel" type indication? • Consider where you would expect fixed structural reference marks (like land wall or intermediate wall) to be located, and how they are usually marked compared to an area where safe navigation is concentrated.

✅ Before You Answer

• Verify in your reference materials how USACE (U.S. Army Corps of Engineers) lock and dam light signals are defined for inland rivers. • Check which features are normally marked by green lights in a vertical line versus red lights or other colors. • Confirm whether walls (land or intermediate) are usually marked the same way as an open, safe route through or around a dam or weir.

Question 1 of 27070

You are upbound approaching a lock and dam and see two green lights in a vertical line. What does this indicate?

The downstream end of the land wall

The downstream end of an intermediate wall

A double lockage is in progress

The navigable pass of a fixed weir dam

Question 1 / 2707066636ee928f7522a1c51a519

Question 1 of 2707066636ee928f7522a1c51a519

You are upbound approaching a lock and dam and see two green lights in a vertical line. What does this indicate?

Back

Question 1 of 27070

You are upbound approaching a lock and dam and see two green lights in a vertical line. What does this indicate?