Mrs Justice Yip said she found it “astonishing” that anyone thought that the “exercise”, in which presenter Jeremy Stansfield simulated a road traffic collision, was a “sensible idea”.
The judge said there was evidence that the BBC had been warned of the danger, yet allowed the experiment to proceed.
She has aired her thoughts in a ruling after Mr Stansfield, who is known as “Jem”, claimed damages from the BBC.
The judge, who had overseen a trial at the High Court in London earlier this year, on Friday awarded Mr Stansfield £1.6 million.
I must say that I find it astonishing that anyone thought that this exercise was a sensible idea
Mrs Justice Yip
She said Mr Stansfield had been presenting an episode of Bang Goes The Theory in 2013 and had assumed the role of a human “crash test dummy” for a feature about the relative safety of forward and rearward facing child car seats.
Mr Stansfield, now 50, was hurt while conducting a “series of crash tests”, then aged 42.
“He was strapped into a rig like a go-cart which was propelled along a track into a post,” said Mrs Justice Yip in a written ruling.
“In the introduction to the piece, the claimant explains that he had calculated the experiment to give a similar crash profile to hitting a lamppost in a real car in an urban environment.
“The crashes were performed forwards and backwards twice each.
“It is not in dispute, and perhaps not surprising, that the claimant suffered some injury.”
She added: “I must say that I find it astonishing that anyone thought that this exercise was a sensible idea.
“On his own account to camera, the claimant was simulating a road traffic collision of the sort that commonly causes injury.
“It might be thought that someone of his intelligence and scientific background might have appreciated the risk.
“Indeed, in the finished piece, he rather prosaically observes: ‘I wouldn’t recommend this.’
“Equally, there was evidence that the BBC had actively sought advice, been warned of the danger, yet allowed the experiment to proceed.”
The judge said she had “not been required to determine liability” for the injuries sustained by Mr Stansfield.
“That aspect of the case was resolved by agreement between the parties,” she said.
“They have agreed to share responsibility for the injuries and resultant losses flowing from the crash tests to the extent that the BBC will meet two thirds of the claim.”
She said her task had been to make findings “as to the nature and extent of the claimant’s injuries and to assess the resultant damages”.
The judge said the parties had agreed that Mr Stansfield should recover “two thirds of the damages assessed as being caused by injuries he sustained when carrying out the crash tests”.
Mr Stansfield said he had been left with with a “constellation of symptoms producing a significant decline in his health”, which and impaired “all aspects of his life, particularly his ability to work”.
He said he had lost more than £3 million in potential future earnings.
The BBC argued that “little more than a moderate whiplash injury with depressive symptoms” could “properly be attributed to the crash tests”.
BBC bosses argued that Mr Stansfield should get “only modest damages”.
“I have found that the claimant was caused injury to his brain, spine and audio-vestibular system in the crash tests,” she Mrs Justice Yip in her ruling.
“While none of the physical injuries were particularly severe, the combined effect together with a psychiatric reaction have caused a constellation of symptoms and problems which have produced a significant impairment in the claimant’s functioning.
“The effect has been to derail the claimant’s successful career in television as well as to restrict his enjoyment of life more generally.”
She said there would be judgment for Mr Stansfield in the sum of £1,617,286.20.
A BBC spokesman said after the ruling: “We take the health and wellbeing of everyone who works for the BBC extremely seriously.
“We keep safety measures on set under constant review and we made adjustments following the incident in 2013.
“We acknowledge the court’s judgment in this complex case and wish Mr Stansfield the best for the future.”