Britain's railways have been judged worst for fares, efficiency and comfort in a study of rail services in Europe.
The report by the thinktank Just Economics said UK rail services were less affordable, less comfortable, slower, more inefficient and more expensive than those in France, Germany, Spain and Italy. Frequency of trains was the only area in which the UK performed better.
"In terms of bang for buck, not only does the UK come bottom of the index of outcomes but it also spends a relatively large amount of money to achieve this woeful result. This means that it also comes bottom of the value for money league," said the report.
"Our under-performing railways carry a considerable cost both for passengers and for the public purse. Our calculations show that a more affordable, more comfortable and faster railway would generate a staggering £324bn in social value (£9.2bn a year) between now and 2050. This is the equivalent of £7 of value per average journey in that period.
"We also estimate that the social, economic and environmental benefits of achieving a modal shift from road to rail – in terms of reduced congestion, accidents and emissions – could potentially reach £154.8bn by 2050.
"When we combine this estimate with our previous figures showing improved outcomes for passengers, we calculate that the total social value of the strategic shift that we propose in this report is in the region of £479bn."
The report was released ahead of the government's response to the McNulty review on the future of the railways, which is expected to be published shortly.
Bob Crow, leader of the Rail Maritime and Transport union, which commissioned the study, said: "This latest research shows that the failures of privatisation are costing the UK hundreds of billions of pounds in social value.
"Instead of addressing that issue and looking at the cheaper and socially beneficial alternative of a publicly owned railway, McNulty proposes more cuts and even longer gold-plated franchises for the private train operators.
"Now McNulty and the train operators want to roll that model out across Europe, smashing up rail services from the North Sea to the Mediterranean."
The report's author Eilis Lawlor added: "Our research puts figures on what anyone who has been to France or Spain already knows – the UK's railways are poor value for money.
"Instead of profitability being the primary measure of success, the wider benefits of the railway need greater consideration.
"The government should act decisively and make an objective and transparent assessment of the best way to organise Britain's railways so as to maximise social, environmental and economic value."