Complex sentence: The Malian portion of the railroad carried an estimated 536,000 tons of freight and 778,000 passengers in 1999, but the track is in poor condition and the line is closed frequently during the rainy season.
Split into simpler sentences: The Malian portion of the railroad carried an estimated 536,000 tons of freight and 778,000 passengers in 1999. The track is in poor condition and the line is closed frequently during the rainy season.