The Cairngorm funicular railway has cost £5m more than was estimated when the project began, it has emerged.
The Cairngorm Mountain Railway has always been controversial
The Economist magazine said taxpayers footed a £20m bill as part of an effort to save Scotland's ailing ski industry.
But it suggested that skiing could be killed off anyway in Scotland due to warmer winters and dwindling profits.
Highlands and Islands Enterprise (HIE) said costs rose because the railway was a complex civil engineering task.
According to The Economist, the mountain railway project was originally expected to lead to expenditure of £12m of public funds.
It said the bill had risen to £14.8m by the time the service opened in December 2001.
But the magazine has calculated that the real cost is now £19.6m.
The Economist described the project as an attempt to keep the tourist trade alive in Scotland's ski resorts.
It said that, with winters getting warmer and flights to snowier resorts in Europe getting cheaper, Scottish skiing is struggling to survive.
Its investigation found that the number of ski passes sold in the major centres has halved since the late 1980s.
The construction of the rail link to one of Scotland's most sensitive landscapes was always controversial, with environmental groups and the Ramblers Association voicing their opposition.
The Economist has suggested that the money put into the project has not been justified even on purely business grounds.
It claimed that Cairngorm Mountain, the company running the service, is losing money and may have to cut jobs to break even.
Most controversially, the magazine suggested that the worst case may involve the railway being closed and taken away, at a further "hefty" cost to the taxpayer.
The next generation of skiers are said to be likely to head abroad
But HIE chairman Jim Hunter defended the railway and said the project had reduced unemployment.
He said: "The main reason (for increasing costs) was that the railway was a highly complex civil engineering project never attempted before in the UK.
"The railway has regenerated the tourism industry and the local Aviemore economy.
"Before the railway, unemployment was about 7.5% but is now 3%."
Mr Hunter rejected claims that the railway had not managed to attract sufficient numbers of tourists.
"The real success is that over and over again, the main critics of this project said our predicted summer visitor numbers were ludicrous," he added.
"We not only made that target but we exceeded it."
Regarding warmer winters, Mr Hunter said: "Had we all been able to forecast the weather 10 years on from when the project was first suggested, we wouldn't be in a job - we would be in a more lucrative one."
Bob Kinnaird, chief executive of Cairngorm Mountain Ltd, said climate change was creating significant problems for Scotland's skiing industry.
But he said the funicular was "one of the most popular tourist attractions in Scotland".
Two of Scotland's best known ski centres are to be put on the market, following a £1m loss over the last two years.
Staff at Glencoe and Glenshee have been told that this would be their last season under the present management.
Glenshee Chairlift Company said it has lost £500,000 in each of the last two years and has blamed poor snow fall and this year's particularly mild winter.