Abstract: A 2,300 HORSEPOWER GENERAL MOTORS ENGINE, WEIGHING 125 TONS (REFERRED TO AS THE DUMPER ENGINE) WAS PUSHING FOUR ORE CARS LOADED WITH ORE CONCENTRATE DOWN AN 8% GRADE. THE CARS WEIGHED APPROXIMATELY 115 TONS APIECE. AS THE DUMPER ENGINE WAS ROUNDING A CURVE IN THE TRACKS IT COLLIDED WITH ANOTHER GENERAL MOTORS ENGINE (REFERRED TO AS THE HOT METAL ENGINE) WHICH WAS COMING UP THE HILL. THE HOT METAL ENGINE DID NOT HAVE ANY CARS ATTACHED. THE HOT METAL ENGINE CREW HAD BEEN INSTRUCTED BY THE FOREMAN TO GO UP THE HILL AND ASSIST THE DUMPER ENGINE IN BRINGING EIGHT CARS OF CONCENTRATE DOWN TO THE SURFACE DEPARTMENT. THE HOT ENGINE CREW WAS IN THE PROCESS OF COMPLETING ANOTHER JOB AND COULD NOT LEAVE RIGHT THEN. THEY WERE TOLD THAT THE CREW ON THE HILL WAS WAITING FOR THEM AND TO GO UP AS SOON AS THEY COULD. THE DUMPER ENGINE CREW, ON THE HILL, WAS TOLD NOT TO WAIT BUT TO BRING DOWN AS MANY CARS AS THEY COULD HANDLE ALONE. THE COMMUNICATIONS SETUP IS SUCH THAT THE ENGINES CANNOT COMMUNICATE DIRECTLY WITH EACH OTHER, BUT MUST GO THROUGH A THIRD PARTY, USUALLY A FOREMAN.