I hate to think of him being hit by this vehicle. Seems as if that equipment gives the driver quite a blind spot. (Photo from Salt Flat Rd. - Google maps)
Generally oil field workers and especially the truck drivers are long off the clock and don't generally run late hours.
I'm thinking more of a pick up with a cattle guard. And hitting someone may not leave as much evidence as you'd think.
I had an across the street neighbor one time literally run over her child in the driveway years and years ago. You wouldn't have known it looking on the driveway.
BTW that child is now a mom to pretty big kids and had oddly enough "minor" injuries from it.