The federal Environment Department has now completed its final recommendation report about the project.

The ultimate decision on whether the project is granted Commonwealth approval rests with Environment Minister Sussan Ley.

The ACT government referred the plans for the city to Woden light rail line to the federal department for the required Environment Protection and Biodiversity Conservation approval in August 2019.

A decision was originally due on January 13 and was initially extended until January 29.

However the timeframe to give a decision has been extended again, one now due by February 3.

A decision could give the go ahead for stage 2A - between Alinga Street and Commonwealth Bridge - of the light rail route to Woden.

The Commonwealth Bridge to Woden route will go through a more complex federal environmental approval process, and must also be signed off on by federal Parliament.

The ACT government decided to break up light rail stage two into two segments - 2A and 2B - due to the complex approval processes.

The project is already facing significant delays with contracts yet to be signed and construction unlikely to begin in 2021 as previously proposed.

It also appears unlikely the stage 2A will be operational, as previously suggested, by 2023.