Painting the walls of the bridges

[roadman65]

I was wondering why the walls on some bridges are painted at the bottom like the overpass in the picture here?  I have seen that in many places in my travels, especially in the North-East this is quite common.

[Big John]

Either to cover up graffiti, or like in Wisconsin, to make the bridge more attractive.

[Jardine]

Would there be any protection against salt spray splashes with paint ?

I park on a slab in my back yard, and just the salt dripping off my rig for 10 years is really rotting out the concrete.  I'm thinking cars splashing salt on a load bearing concrete wall might be of some concern.

But I am just speculating.

[SSOWorld]

Thompson's water seal anyone?

[roadman65]

I thought about graffiti too, but usually they try to match it with the color of the natural concrete.  Plus, I actually used to see it a lot back in the early 70's under many of the Garden State Parkway underpasses with the bottom half green even back then long before graffiti became a problem outside of the big cities.