Network Rail's profits soared above £1bn for the first time in the last financial year, but delays increased – and the track group blamed its missed punctuality targets on squashed commuters.
Almost 730,000 trains ran late last year, which the new chief executive, Mark Carne, claimed was partly due to "congestion as the railway witnessed growth of 5.7 per cent in passenger journeys during the year".
The percentage of trains that ran on time fell to 90 per cent in the year to April, down almost 1 per cent on a year ago and well below the company's punctuality target of 92.5 per cent. But Network Rail pointed out that the number of passengers on the railways has grown by more than 500 million to 1.6 billion over the last decade, while the number of train services has risen by only 16 per cent in the same period.
Mr Carne added that this year's catastrophic winter of flooding had also had an impact. Storm damage, including the destruction of part of the line to the West Country at Dawlish in Devon, cost Network Rail £240m over the year, although more than half of that cost was covered by insurance.
Overall, the state-owned company's pre-tax profits jumped by 29 per cent to £1.04bn, mostly due to accounting gains. Revenues rose to £6.3bn from £6.1bn a year earlier.
"We are in the middle of a rail renaissance," Mr Carne said, "with record levels of passenger numbers and investment. This flourishing sector is investing heavily to improve the railway for today and for tomorrow."
But he conceded that soaring commuter numbers and over-packed carriages posed "challenges" for the network, telling BBC's Today programme that "we need to do more to improve the reliability of the railway".
Mr Carne added: "We did not hit our regulatory targets ... and I think we know we have to do better, and we are very determined to address those issues so that we can provide the high quality of service that passengers expect."
Network Rail said it had invested almost £20m a day in the last 12 months, including the £550m renovation of King's Cross' and a new concourse at Reading station "to unblock one of Britain's worst railway bottlenecks".
But that spending meant Network Rail's debt mountain grew still higher, to almost £33bn from £30.4bn at the same time last year.
The heavy cost of Network Rail's debt, which is guaranteed by the Government, has been flagged as a concern by industry analysts.
The industry regulator, the Office of Rail Regulation, has said that it will approach £50bn by the end of the decade, absorbing a third of Network Rail's budget by 2029.
The taxpayer pays around £4bn a year into the country's railways.
However, Network Rail claimed its cost-cutting over the next five years would see the government subsidy fall to between £2.6bn and £2.9bn by 2019.
Mr Carne added: "Continued investment in our railway will also be key if we are to grow our economy and deliver a better, improving, expanding rail network for millions of daily users."