Complex sentence: Resleepering is already underway with the Outer Harbour Line and Belair Lines already converted, with the Noarlunga Line due to commence in 2009.
Split into simpler sentences: Resleepering is already underway with the Outer Harbour Line already converted. The Belair Line is currently receiving the upgrade to the sleepers, with the Noarlunga Line due to commence in 2009.