It will use more steel than the Harbour Bridge and comprise the longest and deepest rail tunnels ever built in Australia.

The full enormity of the $9 billion North West Rail Link was revealed this morning when the first environmental impact statements into the plan were released.

NSW Transport Minister Gladys Berejiklian ... announced the city's biggest infrastructure project since the Harbour Bridge. Credit:Janie Barrett

The document examines the scope of construction work and outlines impacts on the community such as noise, vibration and local business impacts.

The line will link directly underground into the Epping to Chatswood rail tunnel.