The changes follow a Times investigation that exposed how millions of passengers were being overcharged because of techniques used by train operators to hide cheap fares.
Currently passengers taking a multi-leg journey — changing trains several times — are often forced to pay more when buying one through-ticket than those who purchase a series of singles along the route.
A shake-up of ticketing, initially introduced on the CrossCountry trains network, will see operators forced to offer the lowest priced multi-leg fare every time.
Further reforms will be tested by Virgin and East Midlands trains. One trial will scrap costly fares on little-used routes, while another will introduce “single-leg pricing”, making it easier to buy two cheap singles than a return.
Separately, train companies will be forced to recalibrate every ticket vending machine after it emerged that some devices offer fares up to £100 higher than others in the same station.

A ten-point “action plan”, to be implemented from July, will require operators to flag up the cheapest fares, warn passengers when they can catch a later service to save money and abolish jargon.
There is concern that the ticketing system, where an estimated 16 million fares are on offer at any one time, leaves many passengers paying too much.
The Rail Delivery Group (RDG), which represents train companies, said the overhaul represented the biggest reform of the fare system since 1985 when British Rail introduced the existing pricing structure.
The changes, to be introduced in May under the trial schemes, fall short of reforms demanded after this newspaper’s investigation.

The Times exposed the anomaly of “split ticketing”, when passengers can buy multiple single fares for one rail journey and spend less than the price of a through-ticket. Passengers could save as much as £85 on two thirds of cross-country routes using this tactic.
The RDG said tackling the split ticketing issue was a long-term aspiration.
Martin Lewis, founder of the Money Saving Expert website, said: “When you book a rail ticket, in a station or online, people should be given the cheapest price available at that time for their chosen journey.
“These changes will not make that happen. The changes do include split ticketing, but only where you change train. Most of the big ticket train savings come where you don’t change.”

Demand for Britain’s railways has boomed in recent decades, with some 1.7 billion journeys last year, double the number when the system was privatised in the mid-1990s.
Paul Maynard, the rail minister, said: “We are working closely with industry on a set of actions to improve fares and ticketing. The ticket-buying experience is all-too-often complicated and hard to navigate.”