Built by Alstom as part of their Metropolis family, the trains are the first fully automated passenger rolling stock in Australia as well as the first single-deck electric trainsets to operate in Sydney since their withdrawal from the suburban rail network in the 1990s.

In June 2012, the North West Rail Link project (later Sydney Metro North West) announced that it would use single deck "metro" style trains, rather than the double deck trains more commonly used in Sydney.

[8][9] In May 2013, Minister for Transport Gladys Berejiklian announced that two consortia had been shortlisted for the Operations and Train Systems (OTS) contract.

The winning consortium would build the trains, install signalling and other electronic systems, as well as operate the line as a public–private partnership.

[14] Northwest Rapid Transit subsequently contracted Alstom to build 22 6-car automated Metropolis trainsets for the line, as well as install a communications-based train control (CBTC) signalling system at a cost of $1.7 billion.

[13] In November 2019, the Northwest Rapid Transit public–private partnership was extended to cover the City & Southwest extension.

[31][32] By November 2022, four of these additional trainsets had entered service on the Metro North West Line, ahead of the opening of the City & Southwest extension.

[36][37] As of April 2024[update], the rolling stock contract for Sydney Metro West has not been awarded.

Features of the Metropolis sets include CCTV cameras, internal passenger information display (PID) screens and digital voice announcements.