The Red Line is a rapid transit line of the RTA Rapid Transit system in Cleveland, Ohio, running from Cleveland Hopkins International Airport northeast to Tower City in downtown Cleveland, then east and northeast to Windermere. 2.6 miles (4.2 km) of track, including two stations, are shared with the light rail Blue and Green Lines; the stations have high platforms for the Red Line and low platforms for the Blue and Green Lines. The whole Red Line is built next to former freight railroads. It follows former intercity passenger rail as well, using the pre-1930 right-of-way of the New York Central from Brookpark to West 117th, the Nickel Plate from West 98th to West 65th, and the post-1930 NYC right-of-way from West 25th to Windermere. The Red Line uses overhead lines and pantographs to draw power and trains operate using one-person operation. In 2023, the line had a ridership of 3,469,100, or about 10,800 per weekday as of the fourth quarter of 2023.

One-person operation (OPO), also known as driver-only operation (DOO), one-man operation (OMO), single person train operation (SPTO), or one-person train operation (OPTO), similarly to Driver Controlled Operation, is operation of a train, bus, or tram by the driver alone, without a conductor.