The first Mark I trains were added to SkyTrain's fleet in 1985, when the SkyTrain first opened. A total of 114 trains were originally aquired. 16 more trains were added in 1991, and have different aesthetic features from the original trains, such as no end doors. In 1994, SkyTrain once again expanded their fleet with 20 new trains. These trains have a different interior than the older trains.