Large Single Headed Arrow 24"x48" W1-6
Yellow With Black Copy
Made Of .080 Aluminum Guaranteed Not To Rust Center Mount Holes
W1-6 One direction-arrow warning sign indicates a sharp turn in direction on winding roads and is often used with a curve or multi-curve sign.
MUTCD Guidance (partial exerpt):
...08 When the Hairpin Curve sign or the 270-degree Loop sign is installed, either a One-Direction Large Arrow (W1-6) sign or Chevron Alignment (W1-8) signs should be installed on the outside of the turn or curve.
05 If used, the One-Direction Large Arrow sign shall be installed on the outside of a turn or curve in line with and at approximately a right angle to approaching traffic.
08 If used, the One-Direction Large Arrow sign should be visible for a sufficient distance to provide the road user with adequate time to react to the change in alignment.
Read more at following link.
Source MUTCD 2009 :..http://mutcd.fhwa.dot.gov/htm/2009/part2/part2c.htm#section2C12 -