Balconies Tied Up?

I pass this nearby building under renovation every day on the way to shops or Metro.  I observed what seemed obvious: that the balconies (on all sides) are tied up, and I guessed that it was to prevent them falling from vibration due to the work. 

While taking some photos today I read the large posted construction permit for the first time; it describes the project as rebuilding the roof to create six skylights.  Looking at my photos back in the apartment, and noting that all the ropes are tied to the large tarp on the roof, I realized that they must be holding the tarp down, as shelter for the work.  So the relation of balconies to  ropes to roof is the opposite of my first impression!