Complex sentence: By the mid- 1960s, "The Overland", which ran between Melbourne and Adelaide, required HEP for heating and lighting, because the train was no longer hauled by steam engines which could supply these two features.
Split into simpler sentences: By the mid- 1960s, "The Overland", which ran between Melbourne and Adelaide, required HEP for heating and lighting. Previously, the train was hauled by steam engines which could supply these two features.