The 2nd sentence of the article:
“What’s even more remarkable is that Robertson walks a round trip of 21 miles a day just to get there.”
That means he’s walking 10.5 miles each way.
Scroll down on the link (about half way down) to see the map of his walking route to and from work.
Also note in 2nd paragraph it says the plant manager’s wife cooks dinner for him each day. (But no pay raise!)
Also a video on the page.
A better article but confusing. They talk about a 23 mi trip from his home to the factory and then the miles he walks and then the miles he rides the bus
I guess he walks 12 miles of the trip each way. I was wrong and will admit it. Excuse me for getting confused.