This being road work I'd imagine this was one of several jobs these guys had to do. Another item not taken into account is the wind. Regardless of the weight of such a sign, on a windy day those things will act like a sail and can easily injure someone or blow out into high speed traffic which could potentially cause a monster accident. And yes I do see that it doesn't look like the sign is being erected but just some text being modified. This was most likely on the way to or on the way back from a larger job that required more personnel. It's amazing that so many people can proclaim with absolute certainty they know what's going on from one snapshot.
If you're in the workforce, I'm sure I could make a casual observation of your job and take shots at your lack of efficiency, and probably be just as wrong.
