Road Closed Sign
MUTCD R11-2
The road is closed to all traffic; do not proceed.
What it looks like
A white rectangular regulatory sign with the words ROAD CLOSED in bold black lettering, often paired with barricades bearing red and white stripes.
When you'll see it
You encounter it at the entrance to a road shut down for construction, flooding, a crash, or a special event, usually mounted on barricades blocking the roadway.
What to do
You must not proceed past the sign; stop, turn around, and follow any posted detour or alternate route.
Related signs
Source: Manual on Uniform Traffic Control Devices (MUTCD), 11th Edition — FHWA.