For the Barr government - who this week warned all the officials and politicians squabbling in the back seat over whether Kings Avenue would be a better route than Commonwealth Avenue to pipe down or they'd turn this car around - that point cannot come quickly enough.

Four months out from completion of its first stage of light rail and after having won two elections on the issue, the territory government is having trouble convincing a parliamentary committee to allow it to cross Commonwealth Avenue bridge to get over the lake to Woden.

Until the Kings versus Commonwealth stoush is sorted, the business case for the second stage of the project can't be completed, making it less and less likely the ACT can conveniently roll the workforce from one stage to another and get the contracts signed before the next election.

Dissatisfied with the whole affair, they've threatened to pull the pin on stage two if forced to take Kings Avenue, saying the $1.9 billion price tag that would accompany it is a bridge too far.

Ironically, it's the bridges where the second stage of light rail keeps running into trouble.

Already the $1.3-1.6 billion figure put on the Commonwealth Avenue Bridge route, complete with its wire-free running and Barton dog leg, came with the caveat it could fluctuate depending on when the project began and whether the construction market was still overheated.

Combined with the near billion-dollar cost of the first stage, it makes the $2 billion pricetag on the 54-kilometre, city-wide network proposed by the Stanhope government nearly a decade ago look positively cute by comparison.

Having had two years to get used to the idea of light rail heading south though, the news that stage two was in doubt would have come as a rude shock to some, not least those who'd been buying up slabs of land in the Woden town centre.

Labor announced light rail would go to the satellite city in September 2016 - a month out from the territory election - in what could reasonably be interpreted as a bid to win over voters in the new electorate of Murrumbidgee.

The government said at the time it wanted minimal downtime between the construction of the two stages in order to continue an employment pipeline, and has poured $20 million into geotechnical studies, economic analysis and engineering design in order to make it happen. Another $12.5 million was set aside for project planning and associated works in the June budget.

It set an ambitious timeline, aiming for Commonwealth approval in 2018-19, to sign contracts before the 2020 election, and break ground in 2020-21.

But politicians on the hill threw a spanner in the works by launching a formal inquiry into the project earlier this year.

About 65 per cent of the route to Woden traverses land controlled by the National Capital Authority, and both the authority and the federal parliament will have to rubber-stamp the project before the first sod can be turned.

Liberal Senator Zed Seselja pushed for the inquiry, saying it would provide the extra scrutiny he believed was missing from the first stage of the project.

On that, the Joint Standing Committee on the National Capital and External Territories has certainly delivered.

Transport Canberra and National Capital Authority officials have been hauled before the committee twice now, with its Liberal chair Ben Morton hellbent on figuring out why the ACT government wants to go over Commonwealth Bridge rather than Kings Avenue.

The Griffins’ initial vision for Canberra included many radial rail lines linking different parts of the city, including down Kings Avenue.

The NCA says sticking to the Griffins’ plan would ensure the three jobs hubs at the junctions of the national triangle - Civic, Russell and Parliament House - were served by light rail, without the need to muck up the road geometry by jutting across the parliamentary triangle.

But the ACT says that route would cost $300 million more and would fail to deliver the patronage, uplift in property value and urban renewal it’s banking on to make the project viable.

“Given the lasting, sub-optimal outcomes this would produce for Canberra, the ACT government is reluctant to support it,” Transport Minister Meegan Fitzharris said this week.

Mr Morton has maintained his take on the project is not political, nor is he looking at the route as a whole.

“We are looking at the impact on the national capital area and the parliamentary zone and that is all,” Mr Morton said.

But the territory government - which “welcomed” the inquiry in the same way one welcomes a landlord picking through their underwear drawer during a rental inspection - clearly resents the intrusion.

Chief Minister Andrew Barr was blunt in saying a change in the federal political environment in 2019 would enable his government to “get on” with a number of projects, including light rail, a fast train to Sydney and a city deal.

Ms Fitzharris said Labor governments had a track record of investing in infrastructure in Canberra, including the Majura Parkway and Constitution Avenue, and Senator Seselja had proven he didn't have Canberrans' best interests at heart with his vote against restoring territory rights on euthanasia and his role in the Liberal party room coup against Malcolm Turnbull.

The government points out in its submission to the inquiry it’s not looking at the Woden route in isolation, but rather as one spoke in a city-wide network. Belconnen and the airport will be next, with Kingston, Fyshwick, Tuggeranong, the Molonglo Valley and even Kippax earmarked for future stages.

Only the future extension from Belconnen to Kippax would not trespass on designated areas and thus require the blessing of the authority, it notes wryly.

In her comments this week, Ms Fitzharris said she “encouraged” the committee to think about the broader network when considering their approval processes for light rail stage two, and that she “looked forward” to their final report so the project could “proceed with certainty as soon as possible”. Presumably her statement was dictated through gritted teeth.

But what happens if the federal government doesn't change, the committee rules out Commonwealth Avenue, and the light rail terminates in Civic as threatened?

The situation has Woden Valley Community Council president Fiona Carrick worried.

“It’s created uncertainty in the market. Woden suffered from that uncertainty for many years. We would hate to see Woden [light rail] not going ahead and investment being further entrenched in north Canberra,” Ms Carrick said.

Ms Fitzharris wouldn’t be drawn on whether Woden’s loss would be Belconnen’s gain, only that the timing of future stages would be looked at down the road, and she was sure that the committee would deliver a “timely” report (again, probably through clenched teeth).

But if the north-south spine of light rail was in doubt, would that make the Gungahlin to Civic leg less appealing for commuters?

Professor Graham Currie, who is Monash University’s Institute of Transport Studies Public Transport Research Group director, doesn't think so.

“Stage one is a self-contained project. Its ridership will grow as development in Canberra grows,” Professor Currie said.

“Adding in stage two will boost ridership and if we don’t do it we won’t get that boost. Nevertheless stage one is a great project on its own.”

Professor Currie visited Canberra last week to check out how construction on stage one was going, and believes the project is encouraging “sustainable and attractive land uses” without the need for “endless car parks”.

“Growth is going to happen anyway so more single occupancy cars, more need for car parks and congested roads are coming. Is that what you want? I think it’s better to have options and light rail transport is one of the highest quality options available for advanced cities. It’s time for Canberra to become a big city in a smart way,” Professor Currie said.

He said the “great losers” if stage two was canned were the residents and workforce along that route, who would have to deal with the increase in congestion and car parks in the future.

University of Canberra adjunct associate professor of economics Cameron Gordon thinks it would be better if the government put the brakes on on stage two until stage one actually begins running.

Even then, he believes a demand study for Canberra’s public transport should have been done long before any track slab was laid.

“I’ve always been of the opinion that Canberra can justify light rail in theory but the problem is we haven’t really done a study or based the planning of light rail on where people are now, where they’re going to be in the future and where they want to go,” Dr Gordon said.

“My own personal preference would have been to beef up the bus network then do light rail but they haven’t done that, they’ve decided to do it in one sort of leg.”

Dr Gordon said it wouldn’t matter much if the second stage of light rail wasn't built as “we still need to move most people on buses”.

However he has major concerns about the proposed bus network overhaul timed to integrate with light rail, again because of the absence of a demand study.

“It’s a dangerous thing to have data when you don’t understand what it means,” Dr Gordon said.

“When buses aren’t well patronised it’s assumed people don’t want to take the bus. The fact that just because there’s not many people riding doesn't mean there’s not demand. You need to ask people where they want to go and figure out your network around that.”

Even the academic who revived the idea of light rail for Canberra reckons the second stage could use a rethink.

Professor Peter Newman, from Curtin University's Sustainability Policy Institute, co-authored a study in 1991 that concluded light rail could solve a myriad of Canberra’s existing and future problems, like urban sprawl, pollution and congestion.

Now he says while their overarching proposal - which included traffic calming measures through the city and creating urban villages like the one being built at Macarthur Avenue - is still relevant, the technology has changed so much so that he no longer supports light rail. Instead, he’s begun advocating for trackless trams.

“I’ve been to China recently and looked at the new technology which is significantly better than anything else around at the moment for a 10th of the cost,” Professor Newman said.

“Sydney’s light rail is $120 million per kilometre, the Gold Coast is $127 million per kilometre. This is five to six million dollars per kilometre.”

Those trams are electric with batteries on the roof, and use an optical guidance system to follow dashed white lines instead of having steel wheels on rails.

They have been tested in the Chinese city Zhuzhou and hit the market in 2019.

Because you don’t have to dig up the road or install overhead wires, disruption is likely to be minimal, unlike in Sydney where fed-up business owners have launched a $40 million class action over the bungled build of their light rail. 

However because the trams need to be recharged at stations, the stations become a focal point for building around, just like light rail stops.

“It means land development around stations is still very attractive and urban regeneration will be unlocked in the same way light rail does," Professor Newman said.

Professor Newman believes that technology will overtake light rail, although the transit forms can be complementary.

“It can of course run on the same track as light rail, if it’s a grassed track it could run down there but in other parts of Canberra it would take over,” Professor Newman said.

However, ACT Property Council executive director Adina Cirson said there are economic benefits to be gained from tracks in the ground.

“Rail lines don’t move, bus routes do. There’s no greater certainty for people who are buying land, investing in development, and creating new communities,” Ms Cirson said.

She’s also concerned that the uncertainty around the route going ahead could have an effect on the revitalisation of Woden, which has only just begun.

Developers like Geocon, Doma, Hindmarsh and KDM have invested millions of dollars into land in the Woden town centre, some biding their time for years only for the project now to be up in the air again.

“This really is the problem when politics comes into play with infrastructure projects,” Ms Cirson said.

“This uncertainty for the developers and for the community is not good for the city.”

The uncertainty is something Canberrans are all too familiar with though.

Politicians have been making hay out of light rail since Kate Carnell and her driverless capsules and it's likely to continue until the tram finally gets to Kippax.