Complex sentence: Together, these two sub-systems provide input to the train's cab signals and to a third sub-system, Automatic Train Operation, which can control the trains directly, but which has been temporarily disabled in response to a collision that occurred on June 22,2009.
Split into simpler sentences: Together, these two sub-systems provide input to the train's cab signals. A third sub-system, Automatic Train Operation, directly controls the trains, but has been temporarily disabled in response to a collision that occurred on June 22,2009.