One-man operation driver-only operation (DOO) or one person operation (OPO) is a method of train or bus operation in which the vehicle is operated by the motorman

Motorman

A motorman is the person who operates an electrified trolley car, tram, light rail, or rapid transit train.The term refers to the person who is in charge of the motor in the same sense as a railroad engineer is in charge of the engine. The term was gender-neutral...

 or driver

Driver

-Surnames of people:* Alexander Gooch and Alice Driver , English Protestant martyrs* Andrew Driver , English professional footballer* Betty Driver , English singer, actress and author...

 alone without a conductor

Conductor (transportation)

A conductor is a member of a railway train's crew that is responsible for operational and safety duties that do not involve the actual operation of the train. The title of conductor is most associated with railway operations in North America, but the role of conductor is common to railways...

.

Japan

In Japan, this is used in the operation of many trains and buses which are designated by a green sign on the front of the train reading . The term wanman is the katakana

Katakana

is a Japanese syllabary, one component of the Japanese writing system along with hiragana, kanji, and in some cases the Latin alphabet . The word katakana means "fragmentary kana", as the katakana scripts are derived from components of more complex kanji. Each kana represents one mora...

transcription of one man.