When I worked for the Navy my boss was plowing snow one night with the 87 Dodge W 350 when the blade caught a steel plate. It was maybe 1/4" thick, 5' wide, 20' long. Well, the blade picked it up and it took out the windshield, passenger door, mirror, and cab roof before he could get it stopped. Nearly totalled the truck. This happened on base, so travel speed was probably 10-15 MPH. Lucky for the mechanic he had just gotten out of the passenger seat.
I used to hang my head out the window sometimes when plowing, that was the end of that practice. That steel plate would take a life. Something to keep in mind on those 32 hour shifts.