Complex sentence: The major location is usually the capital city of the particular state, so in the state of New South Wales trains running away from its capital Sydney are "down" trains, while in Victoria trains running away from its capital Melbourne are "down" trains.
Split into simpler sentences: The major location is usually the capital city of the particular state. In the state of New South Wales trains running away from its capital Sydney are "down" trains, while in the state of Victoria trains running away from its capital Melbourne are "down" trains.