What do those red UPS safety flags on the back of the trucks mean?

Question

What do those red UPS safety flags on the back of the trucks mean?

Answer 1

I have never seen anything like that

Answer 2

I just called UPS and they do not use any type of flags on their trucks at all.

The only thing that they did say is that maybe something was hanging out of the rear of the truck..............

1-800- (742-5877)

Answer 3

I am a truck driver and the only flags that a truck would use would be for an oversize load.

Answer 4

I personally have never seen any 'flags' on the backs of the trucks.  If you mean the little squares set on their corner that have different colors, those are used to show that the truck is carrying hazardous materials.  The HazMats can be classified as flammable, explosive, corrosive and a few other categories.  If one of those vehicles is involved in an accident, the local fire dept. responds with a HazMat crew to neutralize any potential threat to people or the environment.