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news
Metropolitan Police stopping distance video in Charlie Alliston trial raises questions
The Metropolitan Police have released a video that they claim shows comparative stopping distances between a police mountain bike equipped with front and rear brakes, and one with no brakes at all.
The video was made public alongside a press release issued yesterday following the conclusion of the trial at the Old Bailey of cyclist Charlie Alliston.
But it raises a number of questions about the methodology used by the Met to conduct their stopping distance tests.
• Was the police rider an experienced fixed gear cyclist? A number of those who have watched the police video suggest the rider in the video does not appear to be experienced at riding that type of bike.
• Did the police test Alliston's bike with and without a front brake to find out what the exact difference in stopping distances would have been?
• Did they test another rim braked bike with thinner road tyres? The police bike is heavier and has fatter tyres which should help it stop in a shorter distance than a lighter bike with thinner tyres.
• Did the police perform multiple runs to establish an average stopping distance?
Alliston, aged 20 and from Bermondsey, was acquitted yesterday of the manslaughter of 44-year-old Kim Briggs, who died from head injuries sustained as the pair collided on London’s Old Street.
However, he was found guilty of causing bodily harm by wanton and furious cycling, and could face jail when he is sentenced next month, with the offence carrying a maximum penalty of two years’ imprisonment.
> Charlie Alliston cleared of manslaughter of Kim Briggs but convicted of wanton and furious driving
It is unclear whether the video released by the Metropolitan Police is the same as one shown to a jury at the trial last week, and we are seeking clarification on that issue and the others raised above. As at the time of publication of this article, we had not received a reply.
During the trial, the Crown did not dispute that Mrs Briggs had stepped out into the road in front of Alliston.
Instead, one of the central pillars of their case was that his bike – a fixed-wheel Planet X track model – did not have a front brake.
Not only did that mean it was not legal for use on the road, but it was argued that if it had been equipped with one, he may have been able to stop in time, or at least that the collision, during which their heads clashed, would have been less severe.
While Alliston was described in court as a former courier – more recently, he has been working as a scaffolder – it is unclear how experienced or skilled he was at riding a fixed-gear bike, although it appears he had been doing so for at least a year before the fatal collision.
Caspar Hughes, who is on the co-ordinating group of campaign organisation Stop Killing Cyclists, told road.cc: “If Charlie Alliston had a front brake Kim Briggs might still have been here regardless of whether she looked before she walked out or not.
“But this terrible case highlights the double standards in how the national press report fatalities by drivers compared to people riding bikes.”
Hughes is a highly experienced fixed-wheel bike rider. He spent a decade as a cycle courier in London, before founding roller racing business Rollapaluza, which celebrates its tenth birthday this week.
We asked him his opinion of the distance it took the second cyclist to stop in the video.
He said: “It is hard to gauge how experienced the rider in the police video is at bringing his bike to a dead stop, but I know I can bring my bike to a halt much quicker than he did using nothing but the drive train.”
Evidence presented by the police at the trial suggested that Alliston had been riding at 18mph and was 6.53 metres from Mrs Briggs when she stepped into the road.
It was claimed that his braking distance was 12 metres but would have been 3 metres had his bike had a front brake fitted – something that Martin Porter QC, writing in the Guardian Bike Blog, said “is frankly absurd.”
Porter, a club cyclist and cycling advocate who has represented cyclists and their families in a number of cases, said that based on a formula in the book Bicycling Science by MIT emeritus professor David Wilson, the stopping distances here would have been 13.5 metres with no front brake, and 6.5 metres if one were fitted.
It’s worth noting, though, that in the police video, the first bike is indeed shown stopping after 3 metres, albeit from a slower speed of 15mph, and it is a different kind of bike to the one Alliston was riding and has two brakes.
Porter also made the point, as others have done, that the braking distance for a car being driven at 20mph – the location where the crash happened – is 12 metres, according to the Highway Code, and that in those circumstances, as well as in this case, reaction time also needed to be factored in.
> Husband of woman killed by cyclist calls for changes to law on dangerous cycling
Simon joined road.cc as news editor in 2009 and is now the site’s community editor, acting as a link between the team producing the content and our readers. A law and languages graduate, published translator and former retail analyst, he has reported on issues as diverse as cycling-related court cases, anti-doping investigations, the latest developments in the bike industry and the sport’s biggest races. Now back in London full-time after 15 years living in Oxford and Cambridge, he loves cycling along the Thames but misses having his former riding buddy, Elodie the miniature schnauzer, in the basket in front of him.
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81 comments
According to the Highway Code, stopping distance at 20mph is 12m, half of that is thinking distance, 6m.
If he was doing 18mph and she stepped out 6.53m in front of him... well, I doubt I could have avoided colliding with her let alone grabbed both brakes first and shifted my weight back!
This whole anti-cyclist culture stinks.
That video clearly shows braking distance and not stopping distance.
There was a recent report stating that the thinking distance in the highway code is too low and we should allow atleast 1 second.
18 mph is a tiny bit more than 8 metres a second.
BTW I've long felt that speed limits should be in metres per second, not miles per hour. 30 mph is great, if you want to know how long it might take to drive one mile - but it gives no sense of speed. 13.4 metres in one second, on the other hand, does give a sense of speed.
How many metres is it from Manchester to London? How many seconds would it take to get there?
In short... no.
That is exactly my point. Speed limits do not exist to inform road users of journey times. They exist to enforce and inform road users' safety. Knowing how long it takes to drive from Manchester to London has no impact on road safety.
As an aside, the last time I drove to Manchester, the average speed was about 20 mph, with large sections of it being travelled on the M6 at less than 5 mph.
Almost certainly such different factors as to be totally inconsistent and therefore should not have been admissible in court.
Unbelievable this “evidence” wasn’t challenged by the defence but it seems it wasn’t…
Also I have read it was “established” in court she wasn’t “distracted” by her mobile phone – yet still seemed to have it in her hand. This doesn’t seem to have been challenged by the defence?! Who the hell was defending him?
I'm sorry but the ONLY valid test here would have been:-
The same bike with and without a front brake, any other test is meaningless
Almost right. To be at least remotely valid, the same bike would have to be used, with a rider experienced in riding both fixie and other bikes, but crucially, the test would have to be done multiple times, with the stop signal to the rider being random, so they wouldn't know whether they were stopping or not. If they knew they were going to stop, the test is not realistic enough to be valid and it should have been challenged by the defence.
This, and same rider weight, in fact because the tester would have known the signal was coming they'd still have a significant advantage, also that of not having multiple scenario unfold plus fear/panic/emotions possibility of being hurt/hurting someone which all takes up valuable time.
Human beings are not fucking robots as plod/prosecution are trying to insist you have to be to be not found guilty.
I look forward to the same set of values being applied on UK roads from now on for all user types with the resulting tens of thousands of motorists being charged with dangerous driving annually for relatively minor incidents that may or may not result in death or injury. the brakes in themselves were in any case not relevant given the timescales involved, the expectation is that he could think faster than any human having had to make multiple decisions/thought processes as I described above. ones that motorists are not expected to do every single day and due to that are absolved with regularity despite other factors in any case even aggravating ones such as excess alcohol.
Almost right. The biggest variable here, IMHO, is the road surface. That video is on perfect tarmac - most cycles don't have suspension or shock absorbers or anti-lock brakes, the quality of the road surface makes a massive difference to braking distances.
You can apply a great deal more force on a perfect surface. If you apply the same level of force to the front break lever on a poor surface and you hit a road defect, your front wheel may bounce up, when it lands it may lock and if it does, you may well go over the handle bars.
like it posited on the other thread. no comparsion between a mtb and a fixie with 1 brake. not a fair comparison at all.
i can almost guarantee i would not be able to stop a roadbike within 3m with two good brakes. Road tyres do not grip the road under heavy braking, they skid, they have always done this, they always will. once the wheel is locked up, that really small contact patch is not enough to stop, it just loses traction and slides. The only other option on a roadbike, with two brakes, is to hard brake the front wheel and try to control the lift of the rear wheel. do this in 3m? never
The whole scenario is a joke.
That's a ridiculous comparison.
They could at least have got a fixie with thin tyres and brakes and get an experienced fixie rider to stop with the brakes, remove them and do without. The guy stopping is clearly not experienced...where was the oh so cool skid?
Oh good, another Alliston thread, but here we go.
Are all rim brakes the same?
Do the police do similar tests on motorised vehicles?
Do the police climb all over trucks just to see what the blind spot is?
The upshot of this case is that we should start to see more rigorous investigative work by the police and more custodial sentences for drivers.
Yes
Yes
Fatal accidents are rigorously investigated. Sentencing is a matter for the courts and the law, and outwith the gift of the police investigation.
So why don't they publicise it like what they done here?
If all fatal acidents are "rigorously investigated" this way then they are obviously an utter shambles....
I seem to remember in a certain case a police investigator claiming that a motorist could not be expected to react within 5 seconds.
When I've read about the police doing similar things with a car which has been involved in a fatal collision, they use the same make and model of car with the same tyres at the same location with the same weather conditions and it is loaded the same. None of which apply to this test, so it is anything but rigorous.
How are drivers in any way related to this? The car is about a woman who lost her life and a cyclist on an illegal, non-roadworthy machine. This has fuck all to do with drivers!
You forgotten which bridge you live under again?
'Cos both cyclists and drivers use the same fucking roads, with the same fucking rules. 'Cos a fucking driver can kill and get a few points for careless driving while an equally carefuckingless cyclist is charged with manslaughter.
Get the fuck with it.
OK?
Oh the irony of this comment when compared with nearly every story I've ever read about a cyclist and car incident.
The only other person who is blamed as much for anything in the news is Donald Trump...who probably once rode a bicycle...
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