An optical communication system includes a first communication system to communicate first information from a controller to a truck and a second communication system to communicate second information. The first communication system includes a first light emitter to output the first information, a first optical fiber to transport the light output from the first light emitter while letting the light leak therefrom, and a first light receiver to receive the light leaking from the first optical fiber. The second communication system includes a second light emitter to output second information, a second optical fiber to transport the light output from the second light emitter and input to the second optical fiber at some point along the second optical fiber, and a second light receiver to receive the light transported over the second optical fiber.