Its not only I-70. I-80 is all semi’s across Illinois. The increased traffic is because of the logistics warehouses popping up like mushrooms. Regional distribution reduces cost. I-80 in Illinois is a major artery for Chicagoland like I-70 in Indiana is for Indianapolis. I would bet there are a ton of centers around Indy.
They've been "popping up like mushrooms", as a wise person once said. ;)
The west-side suburbs, especially Plainfield and Avon, have had distribution centers become a major presence in the last 2 decades.