Complex sentence: By October 2009, more than twenty locomotives had been built and were undergoing road testing, and by April 2010, the last of the fifty locomotives came off the production line, thereby completing the building project in twelve months.
Split into simpler sentences: By October 2009, more than twenty locomotives had been built and were undergoing road testing. By April 2010, the last of the fifty locomotives came off the production line, thereby completing the building project in twelve months.