As ee was driving a loaded hauler away from a backhoe, the right rear trailer tires of hauler fell into a large hole, stopping hauler suddenly. His lt arm struck the steering wheel, rt elbow hit shift tower. He had seatbelt on. He went to a local ER, was treated & released to return to work w/restrictions for 5 days. On Fri 10/29/04 he started losing time from work.