a Power Functions compatible train. These parts were available separately, but mainly online. There was an additional 'collection' pack available with all the necessary parts to power the Emerald Night. These included a rechargeable battery box, a new infrared remote controller, plus a Power Functions motor and infrared receiver. Although this is a "Power Functions" setup, this particular setup existed only for the Emerald Night, as a new motor was in development. The track was unchanged from the RC Trains sets, and in 2009 flexible track was introduced. Following the Emerald Night, the new 88002 Power Functions-compatible train motor and controller were introduced in two 2010 sets, the 7938 Passenger Train and 7939 Cargo Train. This new motor utilized the universal Power Functions connections, used by all components. The standardization of the Power Functions system meant that any of the motors in the Power Functions line could be used and builders were not limited to using a single type of motor as they had been with previous Lego train systems. Powered Up In 2018, Lego introduced a new Power Functions system, known as Powered Up, or Power Functions 2.0. This system was brought to replace the old Power Functions brought about in 2009. This system was introduced with the Passenger Train (set number: 60197) and the Cargo Train (set number: 60198). In 2019, the Disney Train was released, with the motorised elements in the tender. In 2020, the Lego Crocodile Locomotive was released, designed to be motorised with Powered Up Large Motor, not the usual train motor. In June 2022 LEGO introduced the Express Passenger Train (set number: 60337) and Cargo Train (set number: 60336), also powered by Powered Up, which features the ability of the train to be controlled via Bluetooth and a smartphone app. Track gauge Lego trains use a nominal gauge of , based on 5-stud track centerlines gauge. This is circa 5.5 mm wider than O gauge ( – ). The length is not derived by a certain scale ratio. While HO scale is a 1:87 scale (3.5 mm to 1 foot), resulting in a gauge from real life prototype . Conversely, modeling standard gauge into Lego trains would require a scaling of (37.5:1435 =) circa 1:38. With this scale, a minifigure (height ) in real life size would be . Community Lego trains are popular among adult fans of Lego, and Lego Train clubs around