The Texas Department of Transportation’s Maintenance Operations Manual explains when the warning signs should go up:
"Guardrail Damage Ahead" signs should be installed only when substantial damage occurs to guardrail barriers or attenuators which causes them to not function properly.What the manual doesn’t explain, however, is why this warning to drivers is necessary.
Unless the damage is so severe that the guardrail is sticking out into a lane of traffic, no hazard is posed, so what’s the point?
Whenever I see one of these signs, I say to myself, “Wow, thanks for the warning! If I lose control of my car here, it might not be safe for me to hit that guardrail. I must aim for something else.”