The Australian Rail Consortium was the preferred proponent for the South Improvement Alliance - Package 1 of the Australian Rail Track Corporation Ltd (ARTC) Major Works Program (upgrade of the Main South Line from Sydney to Melbourne).

The Australian Rail Consortium comprised of John Holland, MVM Rail and O'Donnell Griffin, with sub-alliance partners KBR, GHD and Connell Wagner.

ARTC's South Improvement Alliance contract with the Australian Rail Consortium saw the provision of about 220 kilometres of new passing loops, extensive upgrading of railway infrastructure and the modernisation of the line's signalling system.

The Sydney-Melbourne rail line upgrade was aimed at increasing line capacity, reducing transit time and increasing rail's share of the multi-million dollar interstate freight transport market. By constructing passing lanes at frequent locations along the track and improving rail infrastructure, transit times will be reduced. No longer will one freight train have to wait idling on a side line while another passes. The upgrade has reduced transit times from Sydney to Melbourne from 13 hours 10 minutes to 10 hours 40 minutes for 1500 metre super freighters, and 11 hours 30 minutes for 1800 metre super freighters.

• the construction of 16 passing lanes consisting of double track sections of around 10km to 15km length of a standard configuration at approximately 10 minute running time intervals with around 220kms total length of new line construction
• new concrete sleepers on selected curves allowing trains to run at faster speeds. This involved about 290,000 new sleepers and recanting to maximum superelevation to facilitate maximum train speeds
• ballast top-up and tamping of existing concrete sleepers over 130kms to achieve maximum train speeds
• boosting capacity to the Dynon / Melbourne Port precinct  by increasing to three the number of bi-direction tracks between Tottenham Junction to Dynon
• construction of a direct standart gauge connection between Brooklyn and Sunshine in Melbourne to provide direct access between the North-South and East-West corridors, and
• installation of eight sets of facing cross overs to minimise operational delays during upgrading and future renewal projects.