Complex sentence: Starting in 2005, the original fleet began to be phased out, and replaced by new Highliners, built by Nippon-Sharyo of Japan, the same company who is currently in charge of production of Metra's fleet of gallery cars.
Split into simpler sentences: Starting in 2005, the original fleet began to be phased out. They were replaced by new Highliners built by Nippon-Sharyo of Japan, the same company who is currently in charge of production of Metra's fleet of gallery cars.