The poor performance of Network Rail (NR) is leading to thousands of extra train cancellations and delays, rail regulators have said.
"Too many people are facing too many delays", said Office of Rail Regulation (ORR) chief executive Richard Price.
Assessing NR's performance for the period April to October 2014, the ORR said train service performance was "generally below expectations".
It added that evidence suggested that the quality of data that NR relied upon to plan and manage works on the railways was "currently in places unreliable" and this could be hindering its efforts to meeting its funded targets.
The ORR said that in the period April to October 2014:
:: There were 46,545 more late trains in England and Wales than ORR had expected;
:: There were 2,730 more late trains in Scotland than expected;
:: There were 18,544 more trains cancelled or severely disrupted in England and Wales than expected;
:: The national trains-on-time figure is currently 89.1% which is 0.7% short of the level expected;
:: NR was making progress on its own two-year performance recovery plan but this was not having the desired effect on punctuality.
The ORR said NR had also reported delivering less work than it planned to do, in both maintaining and renewing the network.
There was a lack of reliable data on bridges, structures and earthworks as well as volumes of work being delivered and this was having an adverse impact on NR's ability to work effectively.
The ORR also said NR had not made the expected progress in the early stages of certain enhancement projects, raising questions regarding its ability to deliver the ambitious enhancements programme.
Mr Price said: " This is vital as too many people are facing too many delays. It is the biggest source of dissatisfaction with the railways, and the industry needs to tackle the problem.
"ORR is also concerned about the reliability of some of the information NR depends upon to take decisions about how to achieve and sustain the high levels of punctuality and financial performance.
"NR has made progress in some of these areas, but not in all of them. Without up-to-date knowledge, NR will not have sufficient understanding of how and why its assets fail and its maintenance approach will remain reactive - leading to inefficiencies and hindering its efforts to improve punctuality.
"The new management at the company has made it clear that it shares our concerns and has committed to address these issues."
Mick Cash, general secretary of the RMT transport union, said: "If the hundreds of millions of pounds bled from our railways by the vultures from the private train companies was invested back into infrastructure we would be able to modernise and expand our railways up to a level that could meet surging passenger demand.
"All the time that our rail network is seen as an open door to a fast buck by greedy speculators reliability and safety will take a back seat. The answer is to end two decades of profiteering and exploitation and return to an integrated and publicly-owned railway run in the public interest."
Publishing its own review of its performance - covering April to September 2014 - NR said its passenger train performance was "behind plan".
The company added: " There are clear improvement strategies in place but these will take time to have an impact on Britain's network, which is seeing continued growth in passenger numbers."
NR said Britain's railways remained the safest passenger network in Europe but workforce safety "remains an area of concern".
NR chief executive Mark Carne said: "The railway continues to see strong growth in passenger numbers.
"However, we know that there are too many passengers that do not get the level of reliability they have a right to expect and that this has a real impact on their daily lives."
He went on: "Increasing capacity on a complex network, at the same time as keeping it running every day, is the challenge we face. We have clear strategies to deliver the improvements required."
Manuel Cortes, leader of the TSSA rail union, said: "Despite massive investment by the taxpayer, £38 billion over the next five years, NR is failing millions of passengers, with more than 10% of services regularly running late.
"They need to up their game, especially when you take into account that those long-suffering passengers are paying the highest fares in Europe."