If a man could dig through rock like he can through earth, it would take him more than 20 years to carve out such a roadcut by himself. This calculation is based on the assumption that it takes eight hours to dig a six-foot grave.
Roadcuts have always amazed me because of the sheer amount of mass and volume so seemingly casually displaced. Difficult and dangerous to build, these feats of modernity are little more than a blur to your typical driver, each one thinking nothing of the great labor it took to make the road. A few seconds and they're through.