The Marunouchi Line is served by Tokyo Metro 02 series rolling stock in six-car trains on the main line, and three-car trains on the Hōnanchō branch. The main line is the most frequent subway line in Tokyo, with trains running at intervals of 1 minute 50 seconds during peak hours. In spite of such high-frequency service, according to a 2008 survey by the Ministry of Land, Infrastructure, Transport and Tourism the Marunouchi Line is one of the most crowded railway lines in Tokyo, but in the 2018 release,the Marunouchi line is one of the more crowded Metro lines, running at 169% capacity between Shin-ōtsuka and Myōgadani stations. Its age and relatively short train length has made it one of the most crowded lines in Tokyo, although the 2000 opening of the Toei Ōedo Line has relieved the problem somewhat. In response to crowding, Tokyo Metro upgraded all stations with chest-high platform doors on March 28, 2009, a date on which it also began driver-only operation. The Hōnanchō branch switched to driver-only operation in July 2004.