WHILE OPERATING SHUTTLE CAR, HE RAN OVER A ROCK IN THE TRAMWAY, CAUSING HIM TO BE JARRED AGAINST THE OPERATORS COMPARTMENT. RULES/REGS NOT A FACTOR; JOB SKILLS NOT A FACTOR; PROTECTIVE ITEMS NOT A FACTOR. AWARENESS, FAILURE TO OBSERVE A FACTOR. DIDN'T MISS WORK UNTIL 8/1/00.