Complex sentence: In 1963 and 1964, the Government of East Germany conducted a efficiency study, which concluded that only if a complete overhaul of the tracks and rolling stock takes place would it make sense economically to keep the narrow gauge railways operational.
Split into simpler sentences: In 1963 and 1964, the Government of East Germany conducted a efficiency study. This study found that only if a complete overhaul of the tracks and rolling stock were to take place would it make sense to keep the narrow gauge railways operational.