Investment in the UK rail network means that 6,400 more train services will be running each week by 2021, according to industry figures.
The Rail Delivery Group (RDG) said about £50bn was being spent on the network, which would result in an 11% rise in the number of weekday services.
The RDG represents Network Rail, which manages the infrastructure, and the train operators.
However, rail unions rejected the figures as hollow promises and PR spin.
The RDG study said that rail companies were already running more than 1,350 extra trains each week compared with four years ago.
The group’s latest projections suggest that by 2021 there will be an increase in train frequency for London commuters and on high-speed England to Scotland routes.
There will also be further improvements covering Kent, the Midlands, north-west England, the West Country and Wales, the RDG promised.
RDG chief executive Paul Plummer said there had been a “capacity crunch” for years as passenger demand increased.
“That’s why we’re delivering billions of pounds of improvements and reversing decades of under-investment…
“It will break bottlenecks, untangle tracks and harness technology so that more trains can run to more places more often.”
Punctuality on Britain’s rail network is at its lowest point in more than a decade.
Last year, 12.3% of trains failed to reach their destinations on time, according to the Office of Rail and Road, the independent regulator for Britain’s railways.
This is the worst performance for a 12-month period since the year ending September 2006, when the figure reached 12.5%.
Lianna Etkind, of the Campaign for Better Transport, welcomed the RDG’s promise to increase the number of trains, as it would “ease the overcrowding which makes so many commuters’ lives a misery”.
But there was scepticism from rail unions.
Mick Cash, general secretary of the Rail, Maritime and Transport union, said: “Like most people, we will believe this when we see it.
“There simply aren’t the trains and staff available to make this plan happen.”
He added: “Like so much of the spin from our rip-off private train companies, these big promises are doomed to turn to dust.”
And Manuel Cortes, general secretary of the Transport Salaried Staffs Association, said: “While I welcome the RDG’s aspiration… I’m weary of their spin.
“I’m sure many passengers… will be asking themselves why rather than always promising jam tomorrow, they simply just don’t get on with running quality train services today.
“UK passengers pay the highest fares in Europe for substandard services and I expect they too will respond to this latest ‘jam tomorrow’ announcement with derision.”