Transport 21, the Government's capital investment programme for the transport system over the next 10 years, is a flawed document which lacks published economic analysis to support the large public expenditure it envisages, according to Dr Seán Barrett of the economics department of Trinity College.

"Individual projects are not costed, but bundled to cost €34.4 billion," said Dr Barrett.

"There is no cost benefit analysis. It ignores all the market alternatives, such as how much cheaper bus fares are where you have competition, and it is remarkably sanguine about the huge cost of over-runs on all the construction projects. There is no mechanism in there to get value for money."

It does not take into account the Comptroller and Auditor General's analysis of the large cost over-runs on national road investment between 2000 and 2006, which had a €10.8 billion over-run on an initial cost estimate of €5.6 billion, he said.

In a review of Transport 21, Dr Barrett, said it shows the lack of any evaluation culture in the Department of Transport and its spending agencies.

"You've got to break it into individual projects and say what they will cost and you've got to have much stricter monitoring," he said.

"It misses the criteria for economic effectiveness and efficiency pretty well at every stage, and it is not the kind of thinking that should underpin the new national development plan to be launched next month."

The rail emphasis in Transport 21 lacks economic appraisals of projects such as the Airport-Swords metro, the Tallaght-Ballymun metro, the Lucan Luas and the Dublin interconnector, he said.

Dr Barrett also said that it had no consumer focus. Competitive bus services are invariably cheaper and more frequent than railways, but Transport 21 ignores the unused capacity of quality bus corridors in Dublin but opts for rail-based solutions for 155 million of the 175 million extra passengers it seeks to attract to public transport, he said.

It ignores the low market shares, high costs, declining productivity and declining yields from rail transport, he said.