Rather than the larger manually operated subway trains used on the other lines in the system, the rolling stock of Line 3 consists of smaller, fully automated, medium-capacity trains, designated by the Toronto Transit Commission (TTC) as the S series, which are Intermediate Capacity Transit System (ICTS) Mark I trains built by the Urban Transportation Development Corporation (UTDC). The trains are powered by linear induction motors, operating on tracks, unlike the city's subway lines and the Toronto streetcar system, which use the unique .