The painting of structures such as bridges and tunnels.
The photo on the right shows an upper bridge of an "underpass" and the wall of an "underpass" after being painted.

2   This is after the inside wall of a tunnel has been painted. In narrow tunnels like this, a sense of fear can arise out of not being able to see the wall, therefore, inclining vehicles to lean over the centerline. For that purpose, tunnel walls are painted white for easy visibility.  
3   Work on the tunnel mentioned above.  
4   This is the painting of a bridge. Rust on iron bridges is a huge problem. Our workers must remove paint that is stripping away with rust, and replace it with anti rust paint.