A SCOOP CAME THROUGH A WING CURTAIN IN THE LAST OPEN CROSSCUT, WATERING ROADWAYS. THE SCOOP BUCKET STRUCK THE BACK REST PLATE OF THE COAL HAULER BEING DRIVEN BY EE. THE IMPACT CAUSED A WHIPLASH EFFECT; THE MUSCLES IN EE'S NECK STARTED CRAMPING AFTER THE SUDDEN IMPACT TO THE SIDE & BACK OF THE COAL HAULER CAB. SCOOP DRIVER DID NOT SEE THE COAL HAULER UNTIL THE IMPACT.