EMPLOYEE WAS WORKING ON TOP OF A RAILCAR WHEN HIS SAFETY HARNESS LANYARD GOT CAUGHT BETWEEN HIS BODY AND A GATE. HE LOST HIS BALANCE AND TRIED TO STEP ONTO AN ACCESS PLATFORM. HIS RIGHT FOOT S LIPPED BETWEEN THE PLATFORM AND THE EDGE OF THE RAILCAR. HE FELL AND SUSTAINED A FRACTURE OF THE RIGHT TIBIA AND RIGHT FIBULA. EMPLOYEE IS LOSING TIME.