Network Rail has announced plans to invest £2.4bn in railway expansion over the next two years.
Network Rail is investing in new tracks and improving stations
The schemes will include lengthening hundreds of platforms, introducing speed increases on certain lines, new tracks and major resignalling.
The improvements will be carried out from this month to March 2009.
Chief executive John Armitt said the investment was a response by Network Rail to the rising demand for rail travel in the UK.
Network Rail will provide £1.73bn in funding, with the rest of the money coming from other sources such as the Department for Transport and local authorities.
Some of the schemes that are to be introduced over the next two years include projects connected with the 2012 Olympics, on which £109 million will be spent by March 2009.
There are also new platforms planned at Manchester Airport station and at King's Cross in London as well as £165m of new track in the Trent Valley.
RAIL INVESTMENT HIGHLIGHTS
New line from Airdrie to Bathgate - £214m (£300m in total)
London Olympics schemes - £109m (£400m)
Trent Valley track doubling scheme - £165m (£300m)
Thameslink station at St Pancras - £78m (£78m)
New station at East Midlands Parkway - £24m - (£24m)
Mr Armitt said: "Three million people use the railways each day, more than at any time in the past 60 years, and we're not standing still waiting for the big infrastructure projects to be delivered.
Mr Armitt told the BBC that the investment would make the experience of using trains "better".
He said: "The improvements we're making, particularly on lengthening platforms, will enable longer trains which reduces overcrowding.
"Improving stations makes people's travel experience better; improving car parks enables them to use the trains and to get less hassle on their journey in the mornings and in the evenings."
The announcement comes after a difficult period for Network Rail. In February, the company accepted the initial findings of a preliminary rail accident investigation which said the train derailment in Cumbria, in which one person died, was caused by faulty points.
Then the Office of Rail Regulation said it was concerned the company was underspending on the railways.
And last week Network Rail was fined £4 million for Health and Safety at Work Act breaches by its predecessor Railtrack in connection with the 1999 Paddington rail crash, which killed 31 people.