The BaT (Bus and Train) project was a proposed north–south tunnel that would provide bus and rail modes of transportation by combining a new underground rail line and busway in a single, double-decked, 15m-wide tunnel beneath the Brisbane River and Brisbane central business district.

The BaT project was planned to be a critical new link in South East Queensland’s public transport network by creating new major transport hubs across the city and inner city suburbs, and facilitating existing locations such as The Gabba, and the new Queen's Wharf development on George Street.

[1] Following a change in State Government, the project was cancelled in March 2015 and replaced by a new Cross River Rail proposal.

In November 2013, the Queensland Government announced a revised plan for the BaT (Bus and Train) project as an alternative to the previous Cross River Rail proposal.

Following public objections, particularly to the proposed walkways from Park Road station, 800 metres away (proposed to provide replacement access to the Princess Alexandra Hospital, the major facility adjacent to Dutton Park station), the government reversed its decision.

The tunnel was now proposed to be situated at the western end of Roma Street station, and involve the demolition of the Brisbane Transit Centre's west tower, with a new building to incorporate the BaT Roma Street station and the Transit Centre's bus terminal.