They do it differently here

So in the US when you come upon a construction site you are expecting it.  There are signs, there are traffic cones, there are guys in orange vests standing around... you know warnings.  In Chengdu, you're driving along and-- Hey! There's a guy in the middle of the street spreading asphalt with a shovel! 

... and yes, that is regular traffic trying to figure out a way to get around the man with the shovel and the machinery. 

Construction sites

I have noticed that in China, nobody looks out for your safety.  You are completely responsible for your own well being.  Other drivers aren't looking out for you, other walkers aren't looking out for you, the government is certainly not looking out for you, and companies are down right out to get you.  So it should not have been any surprise to me that construction sites, in their final stages, are open to the public. 
When serious construction is going on, construction sites are boarded up.  I guess it's too annoying to have to shut down anytime they drop something on a pedestrians' head (or maybe this way they don't have pesky witnesses to the injuries to the construction workers?).  But once the main part of the building was done the blue barriers went away.  I was thrilled, now I could walk on the sidewalk and not have to risk death on the side of the road...  until I saw that construction was still going on.