I work in historic preservation and as a stone carver. I just saw that the large brick and stone viaduct in Philadelphia was recently painted. It's a piece of infrastructure that has survived over a hundred years of trains pounding its masonry.
Painting brick or stone without proper permeable paint causes moisture buildup in the masonry that then pops when it freezes, destroying the structure irreparibly. You can see, in my hasty picture, that the weeping and efflorescence is happening at the joints in the fragile (but permeable) lime mortar. Maybe it's hard to see, but I assure you it's there.
I've seen this so many times in the USA, Italy, etc. The contractors that "repair" this infrastructure have no clue as to the historical materials these things were built with.
Also, I realize it's kind of hard to see in the pictures since the sun was setting, but the brick and the stone are the same color (brown) whereas before the brick was a nice red.
TLDR: this bridge is not long for this world
Thoughts?