One of the teenagers seriously injured in the Alton Towers crash is expected to make a "substantial claim for damages" and expects a criminal prosecution to be seriously considered, her lawyer said.
Vicky Balch, 19, a Sports Performance student from Leyland in Lancashire, was described as being in a "critical condition" in hospital, by Paul Paxton, partner at Stewarts Law.
However, her family have now said her condition is no longer life threatening, but she is undergoing surgery for "significant leg injuries".
According to Sky News, a family statement added: "This is certainly not how she intended to celebrate her 20th birthday today."
Mr Paxton said: "Whilst it is anticipated that there will be a substantial claim for damages to support Victoria in her recovery, the main focus at present for the family is Victoria's well-being and ensuring that the investigation into the accident is carried out swiftly and vigorously.
"They have every confidence in the police and the Health and Safety Executive (HSE).
"It is expected that serious consideration will be given to criminal prosecutions. The family are distraught that a fun day out could turn into such a potentially life-changing disaster."
The other three seriously hurt have been named as Daniel Thorpe, a 27-year-old hotel assistant manager from Buxton in Derbyshire, textile design student Joe Pugh, 18, from Barnsley, South Yorkshire, and his girlfriend, Leah Washington, 17.
Nick Varney, chief executive of Merlin Entertainments which runs the Staffordshire visitor attraction, today said safety measures "were not adequate" at Alton Towers and defended the decision to close a number of other rides.
He said the group was adding "another layer" of safety measures to existing rides as a "precaution" against the prospect of another accident.
Alton Towers has been closed since the record-breaking Smiler ride crashed.
Today, bosses announced it had temporarily shut another Alton Towers ride, Saw, a similar rollercoaster at its Thorpe Park site, and two rides at Chessington World of Adventures - both in Surrey - to "reinforce the safe operation" of the attractions.
Mr Varney declined to comment on reports at least one of the passengers lost a leg following the crash when he appeared on Sky News.
He said "a rather unique set of circumstances (might) have played a contributory factor in the Smiler accident" and said his team was doing "everything" to help those affected.
He told Sky News: "What we have done today is put in another level of additional safety measures across all of our parks that operate these types of rides. All of them - bar two - have been able to implement those new procedures today.
"The two rides at Chessington that are currently suspended will take a few days before we can make the technical and training adjustments to bring them up to the new level of safety protocol - it doesn't mean they were not safe before.
"I think we have had very rigorous protocols across all our attractions. We have had the first - and I hope only accident - in one of our theme parks. We have to make sure that doesn't happen again.
"(Safety measures) clearly weren't adequate on Smiler, because the accident happened. We have taken steps to upgrade safety standards from what were already very stringent safety standards.
"I want to be able to look everybody in the eye and promise them when they come to our parks and get on our rides that they are safe."
The park is reckoned to be racking up losses of around £500,000 a day since the incident and it has also faced accusations staff dithered for 10 minutes before making the first 999 call, despite screams of distress from bloodied passengers on board Smiler.
Bosses today said Alton Towers is to re-open "within the next few days" but the ride involved in the crash will remain shut for the foreseeable future.
Since opening two years ago, the £18 million rollercoaster, which boasts a world-record 14 loops, has been closed twice because of safety concerns.
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