It will make it easier to find tickets on some routes for up to two-thirds cheaper than a direct fare by using "split ticketing" – buying separate tickets for different legs of one journey without changing trains.
On a journey between Glasgow and Dundee, for example, a direct Anytime ticket with no restrictions when you travel costs £26.30. However, by buying three tickets – from Glasgow to Stirling, Stirling to Perth and Perth to Dundee – the total cost is £23.40.
More dramatic savings are possible on some cross-Border routes. A direct, off-peak, fare from Glasgow to Sheffield is £108.70. But by "splitting" the ticket at Chorley, the total fare is £62.
Although it is already possible to get such deals, passenger groups claimed they are often hidden behind the complexities of the rail ticketing system and can take hours to find.
David Sidebottom, director of Passenger Focus, said: "Value for money has become the Achilles' heel of the rail industry, with less than half of passengers in our most recent survey saying their ticket was good value. Some passengers tell us they find the fares system complicated and illogical. We welcome this move to provide more information on pricing, and look forward to seeing increased transparency from the rail industry as a whole."
Transport Minister Norman Baker said its publication would allow passengers to make "more informed choices" by encouraging price comparison websites to seek out the best available deals.
"The Government is committed to providing greater clarity around information and the publication of this comprehensive fare data is a vital first step in providing passengers with a platform to make more informed ticket choices," he said. "In industries where this information has been made available we have seen a raft of price comparison websites and mobile apps developed and I am confident we will see the same results here.
"It is now down to private-sector companies to seize this opportunity and I encourage them to start working on products which can provide real benefits to both passengers and the market."
Ticket information is held on an industry database known as Darwin, which to date has only been available to train companies and those who pay for a licence to use it. Making the data freely available is expected to allow technology firms and even individuals to develop mobile phone apps which automatically search out cheap ticket combinations without the need to spend hours on the internet experimenting with different route options.
An app called Tickety-Split – developed by Martin Lewis, founder and editor of the MoneySavingExpert.com website – can find split-ticket deals. However, the release of the Darwin data is expected to make a raft of such apps available, industry sources said.
Barry Doe, an expert on fares who writes for Rail magazine, said split-ticketing anomalies tended to be more pronounced in England where the services of several train operators overlapped.
"These anomalies have always existed but it was much easier to fix them before rail privatisation because British Rail could simply change the fares. Now it seems impossible to change. I've spoken to some train companies who say they would love to make their fares more consistent but they're prevented from doing so by the DfT [Department for Transport]," he said.
Steve Howes, managing director of Rail Settlement Plan, which is owned by Britain's franchised rail operators, said the release of the data would help the industry keep pace with developing technological trends.
He said: "Providing this data for free is the latest step in a decade-long process that has seen the rail industry make more information publicly available than other transport sectors in this country and other railways overseas"
"Rail passengers in Britain now enjoy access to information on fares and timetables that is unrivalled elsewhere in the world."