By reopening the light rail debate, and putting an estimated $3 billion price tag on Stage 2B, Elizabeth Lee and her colleagues have ramped up pressure on the government to be far more open and transparent about the total cost - and the cost benefit ratio - than it has been to date.

The Barr government has neither rejected the opposition cost estimate nor released a corresponding figure of its own. That would suggest opposition transport spokesman Mark Parton's estimate that it would cost $3.042 billion to complete the line to Woden is somewhere within the ballpark. The same goes for his assertion the first trams would not be running until 2034 - 12 years from now.

Given it is already known that this project is going to cause immense traffic disruption in Canberra's south over more than a decade, and that the cost now appears to be far more than anybody was suggesting when light rail was first mooted ahead of the 2016 election, it would seem reasonable to take the issue back to the people.

It could even make sense for the government, despite its rusted-on commitment to what is essentially a legacy project for Andrew Barr and Shane Rattenbury, to review its vision and to consider more economic alternatives.

While the Barr government could easily spike the opposition's guns by ensuring contracts for the Woden line, complete with punitive cancellation clauses, were in place before the 2024 election, that would be a very dirty trick to play. It is unlikely it would go down well with voters who are either opposed to the extension or starting to become very concerned about how much it will ultimately cost.

And it would not be the act of a "responsible and mature" government; something the Chief Minister claims his administration is.

That is especially the case given that, as yet, the government has not made the business case for the Woden line. No believable cost figures have ever released, there is a near total absence of detail on the timelines, and the final route across the lake and to Woden has yet to be determined.

Is this because the government is unable to crunch the numbers due to its scale and the many known and unknown unknowns? Is it, as is claimed, because they don't want to "condition the market to bid even higher"? Or is it because they don't want to scare the punters with the true facts? Either way, now the opposition has released its own estimates there is a clear onus on the government to either confirm their accuracy or to come up with numbers of its own.

$3 billion is a lot of money in anybody's language but especially so in a small jurisdiction such as this one. If that amount of money is about to be spent on a gold-plated public transport network people need to know what they are getting for their money and when it will be finished.

That said, it is not enough for the opposition to simply say "no" to Stage 2B. They say this would free up billions of dollars to be spent on education, health and other services even after factoring in the cost of an alternative public transport strategy.

So what do they propose? Will it be electric buses, trackless trams or even a combination of the two? How would these services be integrated with the existing light rail service?

If light rail is to be a defining issue of the 2024 election, which now appears certain, there needs to be a fair dinkum debate with full disclosure from both sides of the tracks.

Letters to the editor should be kept to 250 or fewer words. To the Point letters should not exceed 50 words. Reference to The Canberra Times reports should include a date and page number. Provide a phone number and address (only your suburb will be published). Responsibility for election comment is taken by John-Paul Moloney of 121 Marcus Clarke Street, Canberra. Published by Federal Capital Press of Australia Pty Ltd.