EMPLOYEE STATES THAT HE WAS TRAMMING THE RUBBER-TIRED MAINTENANCE VEHICLE UP THE NO.5 ENTRY, WHEN HE ATTEMPTED TO TRAVEL THROUGH SOME OUTBY CHECK CURTAINS, HE STRUCK A SCOOP PARKED IN THE ENTR Y. THE IMPACT CAUSED HIM TO STRIKE HIS LEFT KNEE AGAISNT THE STEERING BOX ON THE MAINTENANCE VEHICLE.