The success of the city to Gungahlin tram line depends on how well it can connect with other forms of transport around the city, University of Canberra planning expert Barbara Norman said on Thursday.
Last week's Acton Tunnel blockage and even natural disasters like New York's 2012 Hurricane Sandy showed that cities which are overly reliant on one form of transport were vulnerable in times of emergency and peak congestion.
Professor Norman faced off with economist David Hughes, who said the government's own figures showed the tram line was a poor infrastructure investment and cost blow outs were almost inevitable.
Dr Hughes said dedicated bus infrastructure improvements would deliver better value for money and that the government should instead consider creative and proven transport options for Canberra.
About 150 people attended the often lively lunchtime seminar, moderated by former chief minister Jon Stanhope. Attendees skewed older and appeared broadly opposed to the tram, but arguments from both sides of the debate drew applause.
A small delegation from anti-light rail group Can The Tram held banners outside the event, one reading "Tram dream = budget nightmare".
"The introduction of light rail to Canberra is part of an integrated, multi-modal [system], not this silly discussion of light rail versus buses, versus cars ... to improve public transport right across our capital city," Professor Norman said.
"Last week's example of [Parkes Way] being taken out due to a truck crash highlights our car dependency ... and the need for excellent public transport alternatives."
Professor Norman said the Gungahlin line could be delivered just as support for urban rail starts to influence decision making from both the territory and federal governments. "It is almost as if stars are aligned," she said.
Dr Hughes told the debate the ACT government had a poor record on major projects and Canberrans could see a decline in other government services due to the cost of the tram. He described the range of factors considered in the project's cost benefit ratio as "increasingly bizarre".
"By the government's own research, I've concluded [the tram] is a poor project," he said.
"When we look at what they add on to get it over the line, to get it past a break even point, they included in the first round parking free revenue. They've included a lot of talk about how they're going to use planning powers to either attract or coerce people to go into the corridor.
"We've see job creation analysis in 2014, that does things like estimate the number of jobs of building and operating the railway... but doesn't take into account jobs that will be redirected from other uses and activities."
Dr Hughes said the project's benefit included 60 per cent of so-called wider economic benefits, or $579 million in value. He said the Gold Coast light rail project, also delivered through a public-private-partnership, had blown out in cost from $950 million in 2009 to $1.3 billion by 2012.
Both experts faced questions about climate change, support among younger Canberrans, the suitability of the Northbourne Avenue corridor and the cost of the city-wide light rail master plan, released by the government on Monday.
The government lodged development applications for the project this week.