Fast train, coming slowly. Maybe. Credit:Bloomberg It boasts that an enhanced link to the Illawarra will slash travel times between Redfern in inner Sydney and Wollongong by more than half to about 35 minutes. But Centurion's proposal is only one of the projects under development and lobbying for government support. They include: A metro-style line from Central Station to Westmead via Olympic Park and Parramatta, eventually linking to the planned Western Sydney Airport.

North-south rail line linking Sydney's north-west to Western Line at St Marys, Bringelly, the South West Rail Link at Leppington and Campbelltown.

With a rapidly increasing population, Sydney and its satellite cities are proving to be a big drawcard for Australian and overseas investors eager to become involved in major rail projects. Under the group's plans, half of the 26-kilometre line from Central to Westmead would be tunnel. Credit:Nick Moir The proposals are in addition to the mammoth government projects under way such as Sydney's $20 billion-plus metro railway, and new CBD and Parramatta light rail lines. Critics say many of the private-sector proposals are pushed by property developers whose primary aim is to unlock housing development and enrich themselves, rather than build public transport where it is needed most. Most of the private-sector projects for rail are predicated on paying for them by placing levies on new homes and businesses. Credit:Holger Mette

But Professor Peter Newman, of Curtin University in Western Australia and a former board member of federal advisory body Infrastructure Australia, said it was an inevitability that the private sector would play a bigger role in public transport projects. "It is absolutely critical to have consortia now. We have been through the era of Stalinist transport planning and it doesn't work – there is no money for it," he said. Centurion and partners China Development Bank and China Railway Engineering Corporation want to complete the so-called missing link in the Illawarra between Maldon and Dombarton, and connect to Port Kembla. Under the consortium's proposal, the dual freight and passenger line would link to a new 12-kilometre section of "high-speed track" between Picton and Campbelltown. It would allow services between Redfern and Wollongong to travel at speeds of up to 250km/h on sections of the line, meaning an express train could complete the journey in about 35 minutes.

At present, a limited-stop service between Wollongong and Redfern takes about an hour and 20 minutes. The consortium says Baird government ministers have told it that the plan for the new rail links in the Illawarra will trigger the "Macarthur Plan", opening the way for the release of land for construction of about 100,000 homes. Using so-called value capture, the group wants to fund the proposed rail link by imposing a levy on new houses in the area of $250 a square metre. The consortium also has longer-term proposals to build a high-speed rail link between Canberra and Newcastle via Sydney's CBD. Under those highly ambitious plans, a 45-kilometre tunnel would run under Sydney, and connect Hornsby, Circular Quay, Central and Western Sydney Airport to Campbelltown and the Hume corridor.

Centurion has been pushing its plans for high-speed line between Newcastle, Sydney and Canberra for a number of years. Its call early this year for the government to enlarge the planned tunnels under Sydney Harbour for the new metro line to make them suitable for bigger trains fell on deaf ears. Another group backed by engineering group BG&E and design company Conybeare Morrison plans to submit an unsolicited proposal to the state government within the next two months for a link between central Sydney and Parramatta. The two-stage project known as the Sydney West Metro Link is aimed at complementing the NSW government's $20 billion-plus metro rail project, which is under construction. The first stage of the private-sector proposal is for a 26-kilometre line from Central Station, Darling Harbour, Bays Precinct, Canada Bay, Strathfield and Flemington, and on to Olympic Park, Camellia, Parramatta and Westmead.

The consortium says it has the support of a "significant number" of large property owners in a development corridor between Olympic Park and Parramatta. One option for later stages is to extend the line west to the new airport at Badgerys Creek. Another is to extend the line east from Central to Kingsford, Maroubra, and La Perouse, where the government has said it is keen to sell Long Bay Jail. The consortium is also open to eventually extending the line to Leppington, where it would connect to the South West Rail Link. In western Sydney, several councils and large property developers such as Roy Medich and Tony Perich are also pushing plans for a north-south rail line linking Sydney's north-west and Campbelltown via St Marys, Bringelly and Leppington. Western Sydney Rail Alliance convener Christopher Brown said the plans for a north-south line would provide a much-needed missing link in Sydney's rail network. "It would unlock Sydney in a blink. It stops western Sydney having to be exclusively car dependent," he said.

Fairfax Media is also aware of other private-sector proposals in early stages of development. Sydney Business Chamber's western Sydney director, David Borger, said extending the South West Rail Link from Leppington to the new airport at Badgerys Creek was the best plan to pursue in the short term. "As the first step, that makes eminent sense because the cost of doing it is by far the cheaper option," he said. "Once we have done that, we need to pause and think about the next step." The political climate is conducive to private transport proposals. Prime Minister Malcolm Turnbull has declared his enthusiasm for "City Deals" that could include developers. Bill Shorten has also said a Labor government would set up a $10 billion finance facility to be accessed through "innovative" infrastructure finance schemes. Grattan Institute transport director Marion Terrill said rail lines were better suited than roads for applying value capture as a means of funding projects.

"Rail is just much more promising because you can identify the beneficiaries much better than you can for roads," she said. "You can more clearly say that the people who live within 500 metres of a railway station will benefit." The plans for the new lines and upgrades to existing rail infrastructure in Sydney and its hinterland come on top of an audacious proposal for high-speed rail from Sydney to Melbourne via Canberra and Wagga Wagga. The proposal is spearheaded by Melbourne group Consolidated Land and Railway Australia. A 2013 feasibility study by the federal government put the cost of a high-speed rail link between Brisbane, Sydney and Melbourne at an eye-watering $114 billion.