Chief executive Bryan Nye said when he saw the $800 million figure and again heard it on the radio he thought the territory must be after one of the world's most expensive tram networks.

He was even more mystified considering Canberra was designed for light rail.

''What I am really asking for is for the government to release the URS report to see where the difference is. There is so much light rail happening around the world. It just doesn't seem sensible.''

A spokesman for Environment and Sustainable Development Minister Simon Corbell, who has clashed with ACT Light Rail over the high projected costs, said at this stage the government had no plans to releasing any more documents.

The ARA, which represents passenger, freight, track, manufacturing, construction, supply and other rail companies in Australia, says the figures need re-examining.

It said including trams, the Tourism and Transport Forum prices a typical light-rail network between $20 million and $40 million per kilometre, making the Canberra estimates of $66 million per kilometre about double the cost of an average light-rail network.

Mr Nye said Canberra was intended to have light rail and so the costs simply didn't make sense.

''The URS figures would make the 13-kilometre light-rail link one of the most expensive in the world and puts the costs of a Canberra light-rail network at about double the cost of the average light-rail system.'' Light-rail networks already in operation had been significantly less costly to build.

''Portland, Oregon's 10-kilometre light-rail network cost $350 million and now has an operating cost of $1.68 per person, which is much lower than Oregon's bus costs of $2.73 per rider,'' Mr Nye said.

''Clearly global experiences are being ignored and so I urge the ACT government to release the data behind the URS cost estimates.''

Light rail could provide many long-term benefits for Canberra.

''One tram can move more than 10,000 people per hour in the equivalent of one lane of traffic that could otherwise move 800 cars,'' Mr Nye said.

''By using renewable energy, trams have the ability to produce zero emissions, helping to lower pollution and noise levels.''

He said Canberra lacked the benefits of the public transport systems enjoyed in Melbourne and Sydney. ''As the nation's capital, the ACT government should be positioning Canberra as a vibrant and exciting urban environment.

''If the ACT government is to improve Canberra's appeal as a place to live and visit, it must improve the public transport available within Canberra and the light-rail system planned by the Griffins will do just that.''

Mr Corbell said on Monday he was sick of the conspiracy theories that cast doubt on a recent transport study for the Gungahlin to Civic corridor.