Triple-Track Train Race is the 18th episode of Season 2 and the 37th episode overall in the series.
Molly and Gil pass by a train station and meet a train engineer and his train, a locomotive named Ol' Number 9. The engineer is preparing for a train race and they tell the others about it. They learn all about trains, including the kinds of trains and the parts that makes them work. Ol' number 9 wins the race.