What does this sign indicate in a construction zone?

• The right lane ends ahead; traffic must merge to the left.
  Explanation:

  "This sign warns that the right lane will end ahead, so drivers in that lane must merge into the left lane to continue safely. Drivers should prepare to merge in advance."
• The left lane ends ahead; traffic must merge to the right.
• The road curves to the right ahead.
• The road goes straight ahead.