Richard Lissack, QC, told the court that the five managers facing manslaughter charges had adopted a "cavalier approach" to safety and "failed very badly" in their duties.
The state of the track was such that King's Cross station would have been closed if work had been conducted according to the book. Some 200 faults had been discovered in the first 43 miles from the London station.
The derailment, in which four people died, was a "disaster waiting to happen", Mr Lissack told the court. If speed restrictions had been implemented, the accident would have been avoided, he said.
Six months before the crash a new rail was sitting alongside the defective line but was never fitted, the court heard. A fault had been discovered at the site 21 months before the crash.
The five executives held responsible - three from Railtrack, which later became Network Rail, and two from the engineering company Balfour Beatty - deny manslaughter. They are Alistair Cook, 50, and Sean Fugill, 50, Railtrack London north-east zone asset managers; Keith Lea, 53, a Railtrack track engineer; Anthony Walker, 46, regional director of Balfour Beatty Rail Maintenance Ltd and Nicholas Jeffries, 53, a civil engineer with Balfour Beatty. They also deny further charges under the Health and Safety Act.
Balfour Beatty denies a corporate manslaughter charge and Network Rail denies health and safety charges.
The Old Bailey heard that the track was in such a poor state on 17 October 2000 that the rail broke into 300 pieces as the 12.10 King's Cross to Leeds express passed over it at 115mph. Mr Lissack said the main focus of the prosecution on the manslaughter charge would be on the defendants' individual involvement in the four and a half months before 17 October.
He said the five men had realised there were a large number of defects which should have been repaired. "The only proper way of dealing with the extremely serious situation was to follow the book of rules of what to do when you have defects. But these defendants chose to go outside the rules."
Mr Lissack said that in June 2000, Mr Walker and Mr Lea met to discuss "the dreadful state of the east coast mainline southern end and how to deal with the long-outstanding backlog of faults, including this track site". They agreed the "clock" would be turned to zero. "All the faults that were overdue for repair were wiped out in the sense that fresh time- limits were brought in to address the backlog which built up."
He said all those charged with manslaughter were complicit in that arrangement. "They knew of it and approved of it and got away with operating a system of crisis management which was far outside the codified approach of doing it by the book."
Between them they had 100 years of experience and their colleagues had described them as diligent, experienced railwaymen who worked hard and did their best. The prosecution said failing to discharge their roles had contributed to the four deaths. "Was this whole sorry tale, with its tragic twist, one in which no one in this court, human or corporate, is not criminally to blame?" asked Mr Lissack.
The 17 October crash had proved to be "a seminal moment in the short troubled history of Britain's privatised railway system". Hundreds of speed restrictions were imposed all over the country in the wake of the disaster. Engineers tried to discover whether "gauge corner cracking", a particular form of rail fatigue which caused the Hatfield derailment, was widespread.
The four victims were Robert Alcorn, 37, and his manager Steve Arthur, 46, both pilots; Paul Monkhouse, a 50-year-old company director and Leslie Gray, 43, a solicitor.
The trial continues today.
MANAGERS IN DOCK THEROCKERS
Five senior managers each face four charges of manslaughter, relating to each of the victims, and a further count under the Health and Safety at Work Act. All charges are denied.
The three Railtrack managers are: Alistair Cook, 50, asset manager of the London North East Zone; Sean Fugill, 50, area manager, London North East Zone; and track engineer Keith Lea, 53. Each is accused of failing in his duty to take reasonable care for the safety of the train passengers. This is said to have amounted to gross negligence which materially contributed to the victims' deaths. The health and safety charge accuses them of failing to take reasonable care for the health and safety of passengers. The two Balfour Beatty managers, civil engineer Nicholas Jeffries, 53, and regional director Anthony Walker, 46, face similar charges.
Railtrack is charged that it "failed to conduct its undertaking ... to ensure ... that persons who travel by train ... were not thereby exposed to risks to their health and safety". Balfour Beatty faces a similar charge and also a charge of corporate manslaughter.