Barr and Corbell now claim that light rail will deliver "$1.2billion worth of benefits to the city". This is substantially greater than the "almost $1billion in economic benefits" that Mr Corbell told a CEDA luncheon in September 2015.

Capital Metro's business Case estimated the benefits of light rail at $984million, including $54million of public transport operating savings benefit. But in October 2015, Barr announced that the bus travel displaced by light rail would be reallocated elsewhere in the bus network. This eliminates the public transport operating savings and thus reduces the estimated value of the benefits of light rail to $930million. The bottom line is that the net benefit of light rail – the amount by which the benefits exceed the costs – will probably be minus $7million to plus $63million.

Leon Arundell, Downer

The illustrations to the article "Spanish-made trams to run on Canberra's city to Gungahlin light rail line" (February 2) raise some questions. The sight of the train running between tall gum trees recalls a trip by heavy rail in England that was delayed at the Nottingham railway station while tree debris was cleared from the track. Will similar experiences plague our light rail, resulting in replacement of the grand eucalypts by smaller, decorative exotics?

The two illustrations of light rail stations along Northbourne Avenue are both bereft of trees, putting a lie to the claim that light rail will not destroy Canberra's bush city entrance.

Robyn Coghlan, Hawker

Bill Deane (Letters, 29 January) implies that if one Somali refugee can make it to the top, so can every Indigenous Australian. He conveniently ignores the fact many refugees, Somalis and others, are not as successful. Is he also implying that we cut funding to help refugees because some don't make it? That's what he is really saying about "dysfunctional" indigenous Australians. In any case, like the admirable Somali, numbers of indigenous Australians do overcome their disadvantages, but they often have to also bear the attitudes of people like Bill Deane. Like the young woman I once met who was told by a high school teacher she would never amount to anything because she was Aboriginal. She went on to become our first indigenous paediatrician. So does her fine example mean all Indigenous people can make it? Of course not.

In any case, why single out Indigenous Australians or migrants?

Can Bill Deane himself assure us that he grasped all the opportunities that came his way and that, consequently, he rose to the top? Opportunities, by the way, that, in our day, probably were more easily accessible to him (and me) than to non-white Australians. Mr Deane suggests we all read the Somali gentleman's recent address. I have and it is great. I recommend Mr Deane, in turn, listen to Stan Grant's speech about his upbringing. It is equally as inspirational — and closer to home.

Eric Hunter, Cook

Dr Richard Denniss' difficulty in understanding the failure of politicians to take climate change seriously (Forum January 30, p5) may be resolved largely by reference to Murray May's letter of the same date.

Mr May draws attention to the deleterious effect of tourism on climate.

There are other areas where reduction of greenhouse gases might be pursued including use of public transport, housing size and Summernats. There is little public response here also.

Politicians realise that too few members of the electorate are sufficiently concerned about the problem of climate change to warrant appropriate government action to combat it.

Eric French, Higgins

Regarding the editorial, "Decriminalisation of drink-driving" (January 29), has our ACT Attorney-General accepted defeat? Or has the danger to road users disappeared? Diminished? Apparently not. It seems that there's so much drink-driving that it's using too much police time. Reduce the incidence? No, let's just ignore it at low levels and thus encourage more of it.

Is it safe at low levels? Science has proven it's not. There's reduced ability to react quickly and make safe decisions even below .05. Alcohol reduces brainpower. Why do people drink then drive? Driving home is often the only way to get home at night and at weekends when public transport is most limited. It's non-existent after 9pm in some inner areas of Canberra and after 6pm or 7pm on Sundays.

Should we reduce the penalty? Or the behaviour? The first might reduce police processing time, whilst increasing costs of ambulance, fire and rescue, hospitals, rehab workers, disability carers, long term income support, lawyers etc, not to mention the trauma for all. Why not reduce the behaviour by attacking causes? Too hard? Time to quit?

Jennifer Manson, Griffith

Erudite contributors to this page confirm the joy of life in our marvellous region is assailed by a few vexations. Local businesses spend vast amounts on making premises attractive, on advertising to entice us into their stores and to win our good will. But rising above the high level of noise inside most shopping malls is additional noise from poor quality sound systems. They barrage us with performances from "entertainers" who substitute using their lips with unintelligible, mournful sounds carried through nasal passages.

Instead of relaxing and evaluating the wonderful merchandise on offer, we forget what we came for and depart as fast as possible. The theory of an enjoyable shopping experience in local shopping centres appears to be ruined by noisy interference.

Don Burns, Mawson

I have voted Labor all my life but the sheer arrogance of this government to go ahead with a project of the magnitude of Canberra light rail and let contracts this close to an election when the project was never put to the people is disgusting. At the last election, all that was in the Labor party policy was a feasibility study not a commitment come what may. I will vote Liberal and attempt to convince as many people as I can to do likewise.

George Beaton, Greenway

For many reasons Terry Fewtrell ("Australia Day can be reshaped with some wattles", Times2, January 29) is on the right track when he supports Jenna Price's suggestion that Australia Day should be reshaped, but I do not think either goes far enough.

The present date celebrates one landing in Sydney, and is understandably offensive to Aborigines as it commemorates a speech by British Governor Phillip on January 26, 1788, giving ownership to his foreign king with little knowledge of its extent, no clue about its future, no recognition of Aboriginal history, and no likelihood that the new owner would ever clap eyes on it.

A proposal that it should be celebrated on a date specially chosen and relevant to all Australians across the entire landscape, with a new and unique flag recognisable throughout the world and, hopefully, a stirring new national anthem, makes sense to me.

It does not have to coincide with the landing in Sydney, or any one special event, but should be wholly Australian. What better day than September 1, with wattle prominent on a new flag, on a climatically logical date, clear of religious and other holiday competition, at a time better suited for vacationing, accommodation and travelling than the present bush fire-prone, hot, cluttered selection?

Geoff Armstrong, Monash

I respect and to some extent support Cynthia Moloney's dissatisfaction with our current national anthem (Letters, January 28) but not her choice of Waltzing Matilda as an alternative. Her comparison with La Marseillaise makes me wonder if she is aware of the origins and content of the French anthem which is a bloodthirsty revolutionary rant with phrases such as "so that an impure blood may fertilise our fields".

The thing Waltzing Matilda has going for it is that it is popular, but a centrepiece of our nationhood? Hardly.

T.J. Marks, Holt

When building consultant Ross Taylor and construction occupations registrar Mark McCabe talk about widespread structural, waterproofing and other problems with new multi-storey flats being mostly related to "design" ("Building industry told to lift game", p1, and "Home unit quality left wanting", Editorial, February 1), it was gratifying to read that they seem to understand the real problem is predominantly interference with design, by (often transitory) developers.

That's bad enough, but developers also push "buying off the plan". That finance-dodging process in which developers seem to have unreasonable veto powers, has the potential to put profit before quality. It should be outlawed so that potential purchasers can substantially see the final product.

To provide further confidence, there should be a compulsory, comprehensive, independent professional audit of all relevant design, inspection, testing, and verification processes (including statutory ones), especially on building work renowned for latent defects. Those processes are explained in International Standards on quality control and assurance, avoided like the plague by most developers and builders. To limit corruption as much as possible, the audits should be paid for by government, and be freely available. That could force developers to achieve better building firmness and watertightness, give greater assurance to buyers, and reduce time, money, inconvenience, and anguish in building rectification.

Jack Kershaw, Kambah

I hope that the member/s of the ACT Legislative Assembly and the bureaucrats responsible for the disasters in new buildings (Canberra Times, February 1) will apologise publicly to everyone caught in the end results of their extraordinary decision some years ago to permit developers and builders to "self-certify" their own constructions.

I hope the Assembly will fully compensate home owners caught out by that absurd removal of controls, even to the extent of knocking down unfixable buildings and replacing them at no cost to their unfortunate owners. This has been a clear case of virtual government-enabled fraud and abuse of consumers.

I am reminded of the rationalisation I heard given by Alan Greenspan, a past head of the US Federal Reserve, when discussing the rapidly developing Global Financial Crisis. Interviewed on radio during 2008 as the GFC was rapidly developing, Greenspan told the interviewer that he had agreed with the US government's removal of the key financial controls which prohibited the kind of toxic loan packages later sold by major financial houses such as Lehman Brothers, because he did not think the gentlemen of the finance industry would do what they actually did, if their leash was removed. How wrong he was, as were our local government's members.

Terence Craig, Holt

I wholeheartedly support Rosemary Walters' suggestion that all incoming politicians be given short courses in climate science and economics (Letters, January 26).

I'm sure the climate change course will include a chart that plots the temperature predictions of the suite of climate models used in IPCC reports and actual surface and atmospheric observations. Those advocating strong action on that element of climate change caused by human activity should then explain why they wish to use these flawed models as the rationale for policies that would reduce economic growth in advanced economies and deny it altogether to the third world. The most important lesson for any new politician about economics is that every dollar the government spends it must first take from another person through taxation. Governments cannot create additional economic activity through spending, only change where it occurs. That change occurs at the expense of the general population.

While some spending is justified, governments should not be spending money for the sake of employing people or "stimulating" the economy.

One of those incoming politicians will surely propose shifting the burden to corporations by increasing the company tax rate. The second most important lesson is the difference between the legal and the economic incidences of taxation. While you can legally compel a company to hand over the cash, the actual cost will always be transferred to consumers through higher prices or employees through lower wages or lower employment.

Stephen Jones, Bonython

Many thanks to Mr Norman Lee for his sage advice on bicycle riding etiquette (Letters, January 28). As a regular bicycle commuter I am well aware of the nature of his "signal that he was behind them and couldn't overtake" and I am sure I speak for countless others when I say many thanks for that. Apparently the possibility of drivers having to show patience and courteous behaviour is completely out of the question. Instead his suggestion is to ban cycling pelotons if they in any way delay a "motor car owner" . In reply to his suggestion for registration and road tests for cyclists, bring it on and I look forward to hearing his "signals that he wishes to overtake" as I take my rightful position in the centre of the lane.

Matthew Sandford, Farrer

Before the last federal election the Coalition swore they would stick with Gonski. As soon as they won they tried to ditch it, until a chorus of protest made them reconsider – they wouldn't keep the Gonski methodology but they would provide the funding.

History shows the Coalition is implacably opposed to the Gonski method, and their way of squirming out of it was to offer the funding without the reform. Now they accuse Labor of offering funding without reform. But the whole point of Gonski was to identify funding shortfalls first, then fix them.

Minister Birmingham's criticism of Labor's renewed commitment to Gonski – that it is funding without reform – is not just plain wrong; it's hypocritical. If he were right that there are more important things than funding, why do the Coalition always try to give more public money to private schools which already have plenty of their own?

S W Davey, Torrens

FOOD FOR THE CHOOKS

I see that same-sex marriage and the republic are back in the headlines – a sure sign that the second Sydney airport and the very fast train distractions are soon to get another run. As Joh Bjelke-Petersen used to say: feeding the chooks.

C. McKenzie, Lyneham

SCRAP THE EXEMPTION

The shoddy apartments problem (Editorial, January 1) can be easily fixed by removing the exemption for compulsory builders' defect insurance when new structures are above three storeys. It only benefits shoddy developers and, not surprisingly, they asked for it.

Chris Emery, Reid

A ROLE FOR ABBOTT

I suggest Malcolm Turnbull appoint Tony Abbott as special Minister for Aboriginal and Torres Strait Islander issues. It would signal a higher profile for this important topic and give Tony a meaningful – since he took it on as a task for his prime ministership – outlet for his energy and talents.

James Walcott, Mawson

SHAMEFUL TWEETMENT

To the man who used social media to humiliate Roosters' footballer Mitchell Pearce: "Tweet others as you would like to be tweeted."

Peter Day, Queanbeyan, NSW

HER MAJESTY'S PROXY

What is it that David Smith, of Mawson (Letters, January 30), does not understand about "the Governor-General of the Commonwealth of Australia, being the representative in Australia of Her Majesty Queen Elizabeth II"?

Roger Terry, Kingston

EARLY BOAT PEOPLE

There has never been a land bridge that people could walk across to come to Australia (Neil James, Letters, February 2). The sea crossing was always substantial. A fleet of Aboriginal ancestors most likely did arrive 50,000 years ago.

Peter White, Flynn

OUT OF BABYLONIA

In reply to Ken McPhan (Letters, February 1), I stand corrected. But rather than Africa, I would suggest the ancient Babylonia "from thence the Lord scattered them abroad upon the face of the whole earth" Genesis 11:1-9.

Evelyn Bean, Ainslie

BLAME DEREGULATION

With all regulation and tape disposed of, courtesy of aggressive building industry lobbying, why be surprised buildings are falling down, leaking like sieves and clad with combustible material

Albert M. White, Queanbeyan

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