Double Curve Sign (Reverse Curve)
The double curve sign, also called the reverse curve sign, is a diamond-shaped yellow warning sign with a black S-shaped arrow showing two curves in opposite directions. The first curve goes one way and the second curve goes the other — forming an S-shape. This sign differs from the winding road sign in that it shows exactly two curves rather than a series of three or more. The arrow indicates which direction the first curve goes (left or right), so you can prepare your steering. When you see this sign, reduce your speed before reaching the first curve. You'll need to steer one direction and then quickly adjust to steer the other direction for the second curve. The transition between curves is particularly challenging because you're changing direction while the vehicle's weight is still shifting from the first curve. This creates a higher risk of losing control, especially in wet conditions or at higher speeds. Double curves often have advisory speed plates below them recommending a safe speed. On mountain roads and winding routes, you may encounter multiple double curve signs in succession. Always complete each set of curves before accelerating.
Rules & What to Do
Slow down before the first curve. Maintain a steady speed through both curves. Do not brake in the curves. Stay in your lane through the direction changes. Follow the advisory speed if posted. Be extra cautious in wet or icy conditions.
Penalties
No penalty for the warning sign itself. Losing control on curves due to excessive speed can result in citations for unsafe speed ($100-$300) or reckless driving ($200-$500+).
For Commercial Drivers
Double curves are dangerous for commercial vehicles because the weight shift from the first curve hasn't settled before you need to shift direction for the second curve. This creates a rocking motion that can lead to rollovers, especially for top-heavy loads. Reduce speed well below the advisory speed. Tanker drivers face liquid surge that amplifies this rocking effect. Maintain consistent speed — don't accelerate between the curves.
Frequently Asked Questions
What does the double curve sign mean?
The double curve (reverse curve) sign warns of two curves in opposite directions — an S-shaped road ahead. Slow down and be prepared to steer in one direction, then quickly adjust to the opposite direction.
What is the difference between a winding road sign and a double curve sign?
A double curve sign shows exactly two curves (an S-shape). A winding road sign shows three or more curves in alternating directions. Both require you to slow down, but winding roads involve a longer section of curves.