Half a mile is plenty of time for drivers to merge out of the two right lanes. Post this sign to keep the right lane clear. Signs increase safety and prevent accidents.
Standard: 01 The Lane(s) Closed sign shall be used in advance of that point where one or more through lanes of a multi-lane roadway are closed. 02 For a single lane closure, the Lane Closed (W20-5) sign shall have the legend RIGHT (LEFT) LANE CLOSED, XX FEET, XX MILES, or AHEAD. Where two adjacent lanes are closed, the W20-5a sign shall have the legend 2 RIGHT (LEFT) LANES CLOSED, XX FEET, XX MILES, or AHEAD.