Brisbane's underground bus and rail project will be named the BaT Tunnel, the Queensland Government has announced.

The name, which is short for Bus and Train Tunnel, was proposed by Capalaba resident and RACQ Insurance motor claims service officer Lynne Doyle who has won six months of free travel.

The tunnel's name has already been questioned by commuters, because the entry guidelines for the competition specifically ruled out using acronyms.

The proposed names must be "original" and "not too similar to an existing name" under the guidelines.