This week's high-speed rail industry briefing in Newcastle has answered some questions and posed a whole series of others about the Sydney bullet train.
High Speed Rail Authority chief executive Tim Parker and chair Jill Rossouw told industry leaders from around the world that a high-speed line could be finished by 2037 and that at least 50 per cent of the 165-kilometre route would travel underground.
The presentation laid out what seem to be emerging as parameters for the project: a one-hour travel-time between Broadmeadow and Central; one stop at Gosford and possibly another where Lake Macquarie meets the Central Coast; and a dedicated line running only 250km/h-plus high-speed trains.
In the yet-to-be-decided basket is a continuation of the underground line for another 10 minutes to Parramatta, which would open a large, new passenger base and could make the project more politically attractive given the swathe of electorates up for grabs in western Sydney.
How will passengers get to the HSR?
The HSRA will have to design a system which drags people out of their cars, a key challenge in making the line both useful and commercially viable.
The point-to-point nature of the HSR line outlined by Mr Parker means the service will have to rely on large numbers of people living close to the Broadmeadow and Gosford stations.
Anyone living in between will need to have reasonably easy access to either of those two stations via the existing rail service, dedicated buses or cars, otherwise they will keep driving to Sydney instead.
The same applies for those living in the big growth areas around Maitland and Cessnock.
Will these people drive into a big commuter car park at Broadmeadow, or will the government establish a new express rail service or rapid buses to encourage them not to burn down the M1?
A similar challenge exists in Sydney, where the HSR line will have to integrate well enough with the suburban rail network to discourage car travel.
Newcastle Herald columnist Phillip O'Neill wrote in February that train fares paid on the Newcastle-Sydney line contributed less than 10 per cent of the cost of operating the service, which is the most subsidised rail line in the wider metropolitan network.
Who will use the service?
The HSR trains will have fast wi-fi and could offer a "premium service", but the authority must make the line cheap enough to attract more than well heeled business passengers.
Mr Parker's vision includes ordinary people travelling to medical appointments and other services.
Questions of equity arise around both price and geography.
If tickets on the HSR are expensive, will the state government continue to operate the existing train service all the way from Newcastle to Sydney?
Will residents in the less well heeled suburbs of Sydney and Newcastle have fair access?
The HSRA believes businesses are more likely to establish offices in Newcastle if the HSR can connect them quickly to Sydney.
The authority also sees tourism benefits for Newcastle and the Lower Hunter.
The HSRA was giving little away on Wednesday when quizzed about whether existing services would continue.
"High-speed rail would be a new and completely separate service to existing inter-city services," a spokesperson said.
"Service patterns for existing rail services are a matter for the individual transport agency.
"All transport agencies would work closely to ensure the most beneficial connectivity for passengers."
What happens to the rail line in Newcastle?
Mr Parker said it would make sense to run light rail from Newcastle Interchange to the HSR station at Broadmeadow.
If so, will Newcastle still need a heavy rail line between Broadmeadow and Newcastle West or will an extension of the city's tram line do the job?
The NSW government's Hunter Park strategy proposes trams running along Tudor Street to Broadmeadow. Could light rail run along the heavy rail line, via Hamilton Station, instead?
The inner-city experience has demonstrated how disruptive building a light rail track along the road can be, including the loss of parking and a sometimes fatal impact on business.
If train commuters want to travel east beyond Newcastle Interchange, they need to transfer to a tram. It will make little difference to these passengers whether this happens at Newcastle West or Broadmeadow.
Cutting the heavy rail line at Broadmeadow, which has been investigated before, depends largely on how important a destination Newcastle West is in its own right.
If enough people want to travel to Newcastle West and no further, then trains should probably continue to the interchange so these passengers do not have to switch modes.
Does the Opposition support the project?
The HSRA leaders said the government would make an investment decision next year and, if approved, the project could start locking in building contractors in 2027.
Committee for the Hunter chief executive Alice Thompson, a former infrastructure adviser to former PM Malcolm Turnbull, said on Tuesday that the HSRA's public airing of a timetable suggested the government was serious about funding the project.
But Peter Dutton could be prime minister by the middle of 2025, raising questions about whether a Coalition government would agree to spend tens of billions of dollars on the project.
Shadow transport minister Bridget McKenzie told the Newcastle Herald that "faster" rail connections to Newcastle and the Central Coast were "critical to the region's economic future and aligned with the Coalition's regionalisation plan".
"The former Coalition government was delivering a fast rail connection within this decade, but Labor scrapped it, delaying any benefits for commuters," she said.
Senator McKenzie's comments refer to $1 billion the former government pledged, just before the 2022 election, to speed up the existing rail service by several minutes with track improvements between Tuggerah and Wyong.
A broader suite of unfunded measures was forecast to cut travel times by about 35 minutes, but the Labor government canned the initial project in favour of a dedicated HSR line.
"The Coalition is committed to delivering the high-speed rail business case," Senator McKenzie said.
"To date, Labor is yet to provide any details on where it's proposal is going, what it will cost or who will be paying for it."
