Alton Towers operator Merlin Attractions has been fined £5 million after admitting health and safety breaches over the Smiler rollercoaster crash.
Two teenagers - Vicky Balch, then 19, and Leah Washington, then 17 - each lost a leg in the collision in June last year which "changed the lives of some of those injured in the most dramatic way", according to a judge.
Stafford Crown Court heard that the victims had watched with "disbelief and horror" before ploughing into an empty carriage on the track, with the impact likened by the prosecution to a 90mph car crash.
The company was fined after the court heard that an engineer "felt pressure" to get Smiler back into service after it developed a fault shortly before the devastating crash.
An expert witness report, compiled by consultant Stephen Flanagan, also said Alton Towers management linked bonuses to "acceptably low levels of downtime" on their rollercoasters.
Judge Michael Chambers QC called the accident a "catastrophic failure" by the company involving basic health and safety measures.
He said the "obvious shambles of what occurred" could have been "easily avoided" by a suitable written system to deal with ride faults and a proper risk assessment.
The judge added: "This was a needless and avoidable accident in which those injured were fortunate not to have been killed or bled to death."
He said the injured "endured great pain and distress" while waiting for medical help, with the first 999 call not made until 17 minutes after the crash. It took up to five hours for them to be freed from the wreckage.
He added: "Those in the front row bore the brunt of the collision and had their legs crushed in the tangled steel."
He said that all 16 people aboard the carriage had been "injured to various degrees", adding that the company's safety failure had been "putting at risk the safety of thousands of young people and children".
Of those affected, he said the most moving accounts had been from the families of those hurt, some of whom had to give up careers and move home in order to care for their loved ones.
The judge said the relatives and the injured had shown "great courage and fortitude" in the aftermath.
Beginning sentencing, he said: "Human error was not the cause as was suggested by the defendant in an early press release.
"The defendant now accepts the prosecution case that the underlying fault was an absence of a structured and considered system not that of individuals' efforts, doing their best within a flawed system.
"Members of the public have been exposed to serious risk of one train colliding with another with a computer control system was reset, having been overridden to address a fault."
Miss Balch, Miss Washington, fellow front-row passengers Joe Pugh and Daniel Thorpe, and Chandaben Chauhan, who was sitting in the second row, were all seriously injured when their fully-laden 16-seater carriage was crushed against the other car.
Prosecutor Bernard Thorogood told the court on Monday that the passengers on the £18 million rollercoaster watched with "disbelief and horror" as they realised they were going to collide with an empty carriage in the bottom of the Cobra Loop section.
Lawyers for Merlin said that the company had seen a £14 million drop in revenue as a result of the crash, and had "got the message", making 30 changes to safety measures, equipment, and training.
The firm's barrister Simon Antrobus said although there had been human errors which led to the incident, Merlin accepted it was at fault.
Asked by the judge if anyone had resigned over the failings which led up to the horror crash, Mr Antrobus replied: "No".