Complex sentence: By placing the two round-end observation cars at each end of the passenger cars, the railroad eliminated the need to turn the train around at the terminals; only the locomotive had to be turned around at the completion of each trip.
Split into simpler sentences: By placing the two round-end observation cars at opposite end of the consist they eliminated the need to turn the train around at the terminals. Thus, only the locomotive had to be turned around at the completion of each trip.