These three new lines were intended to expand the capacity of the CityRail network and extend it to serve new areas.

This differed from the CBD Rail Link which utilised the MetroPitt corridor and crossed the harbour to link into the North Shore and Chatswood to Epping lines to the north and either the Airport or Campbelltown Express lines to the south.

This concept envisaged limited stops trains commencing from Wynyard, then utilising the CBD Relief Line, the "Main" pair of tracks on the Main Suburban line and the Western and Richmond lines to provide faster & more frequent travel between the Sydney CBD, the Parramatta CBD and the outer Western Suburbs.

The Government claimed this would enable a 5-minute reduction in travel time and a 90% capacity improvement between Wynyard and Parramatta, and a 10-minute reduction in travel time and a 50% capacity improvement between Wynyard and Penrith or the Richmond branch line.

[2] In early 2011, the then Liberal–National state opposition indicated it would defer the project, preferring to instead focus on the North West Rail Link.