To out-weigh the cost of making it, it has to run 24/7

“Built by Krupp, seen here crossing a federal highway in Germany en route to its destination (an open-pit coal mine), it is cheaper to move the thing like this, than to construct or re-assemble on-site.The mover stands at over 311 feet tall and is over 705 feet long. It weighs over 45,500 tons (yes that’s 45 thousand tons!) Cost $100 million USD, took 5 years to design & manufacture and 5 years to assemble. It only requires 5 people to operate it. The Bucket Wheel is over 70 feet in diameter with 20 buckets, each of which can hold over 530 cubic feet of material. A 6-foot man can stand up inside one of the buckets. It moves on 12 crawlers (each is 12 feet wide, 7′-10″ high and 46 feet long).There are 8 crawlers in front and 4 in back. It has a maximum speed of 1 mile in 3 hours (1/3 mile/hour). It can remove over 76,455 cubic meters (100,000 large dump trucks at 40Yds. each of overburden per day).”

others of this family found http://mining-technology.com/