Grooved Pavement Sign
MUTCD W8-15
The pavement ahead has been grooved or textured (often before resurfacing); the ride can be rougher, and motorcyclists should use extra caution.
What it looks like
A yellow diamond-shaped warning sign with a black legend reading GROOVED PAVEMENT.
When you'll see it
On road sections that have been ground down or textured, usually ahead of resurfacing work in a construction zone.
What to do
Expect a rougher ride and reduced traction; slow down and, if riding a motorcycle, use extra caution over the grooved surface.
Related signs
Source: Manual on Uniform Traffic Control Devices (MUTCD), 11th Edition — FHWA.