Architectural Photography - Strange structure

I am posting this photo for @photocontests sponsored by @juliank

This is an original photo I took with my Samsung phone. Came across this strange walls just next to the highway to Nelspruit.

I know you wondering what are they for and what is their purpose...don't worry you not alone, I am also just wondering too as they just next to the highway.

• Camera used: Sumsang J5
• Lens: 4 mm
• ISO: ISO-40
• Exposure time: 1/528 sec
• Location: South Africa (Nelspruit)

Maybe someone from Nelspruit can tell us...