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Metropolitan Police stopping distance video in Charlie Alliston trial raises questions

Police claimed fixed-wheel rider could have stopped in 3 metres to avoid collision with Kim Briggs if he’d had front brake – but is that feasible?

 

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

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BikingBud | 6 years ago
4 likes

As a safety engineer and investigator, I find that there is a lot of pontificating and postulating about what may or may not be fact and relevant but the point is this prosecution has been about blame rather than improving road safety.   

We are mostly working on limited, prejudiced, snapshot of the incident and are therefore focussing on the "he said -she said" and not a critical analyisis of the evidence.

To address the root cause and reduce the possiblilty of recurrence requires a differnt standard of investigation to what we have seen here.

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BehindTheBikesheds replied to BikingBud | 6 years ago
0 likes

BikingBud wrote:

As a safety engineer and investigator, I find that there is a lot of pontificating and postulating about what may or may not be fact and relevant but the point is this prosecution has been about blame rather than improving road safety.   

We are mostly working on limited, prejudiced, snapshot of the incident and are therefore focussing on the "he said -she said" and not a critical analyisis of the evidence.

To address the root cause and reduce the possiblilty of recurrence requires a differnt standard of investigation to what we have seen here.

You've basically said nothing about the 'evidence' put forward by the prosecution nor its merits, if any and the testing methodology. Why, if you are qualified in such and have bothered to post a comment (that actually says not very much at all) have you not then gone onto state what is correct, what isn't?

How do you interpret the testing comparative to the incident itself?

How do you interpret the use of a totally different bike, weight of person (that aren't  specified) and not similar speed at impact offered up by the prosecution (as low as 10mph)?

How do you interpret thinking time in panic/real life situations to 'lab' testing such as seen in the video?

What timescales do you use for thinking and mechanical action time in unknown event incidents?

How does multiple scenarios one after the other (i.e. ped steps out unexpectedly and you shout and brake - after thinking, you then think again to avoid (which in this case happened), then have to rethink again when the ped steps back into you a couple of metres away. How much time do you think that adds up to and does that in fact mean that as the ped steps back the convicted would have plenty of time to rethink and apply the brakes or no chance at all?

How does this impact on that thinking time, does it increase /add up, due to overload or is it somehow reduced to one single set of thoughts that somehow according to the 'investigators' meant he had ample time to come to a complete stop in 3 metres if he had the front brake?

Do you think it fair to use the whole distance/time from first seeing the ped step off as the total timescale/distance to stop the bike when in 99.99999% of similar scenarios (a hazard crossing in front of you or potentially doing so) you wouldn't slam on the brakes in the same way as per the 'test'?

What is your interpretation of the charges, should this in fact be a 'Con and Use' infraction as is normally used against motorists for same/worse scenario's?

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fenix | 6 years ago
4 likes

You don't have right of way just by stepping out into the road. She couldn't have looked. A silly mistake.

Are you suggesting that he hit her on purpose ? What cyclist would do that ? He's just as likely to be hurt if not more likely.

His mistake was to ride a bike that wasn't legal on the road. If he's had the front brake he would probably still have hit her but at a lower speed and probably caused less harm.

His mistake was also to be a nob after it.

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Nymeria replied to fenix | 6 years ago
0 likes

fenix wrote:

You don't have right of way just by stepping out into the road. She couldn't have looked. A silly mistake. Are you suggesting that he hit her on purpose ? What cyclist would do that ? He's just as likely to be hurt if not more likely. His mistake was to ride a bike that wasn't legal on the road. If he's had the front brake he would probably still have hit her but at a lower speed and probably caused less harm. His mistake was also to be a nob after it.

 

She still has right of way... you might not like it but that is the law. If a child runs out into the road and a car hits them because they're driving too fast, the driver is in the wrong. It is no different for cyclists.

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beezus fufoon replied to Nymeria | 6 years ago
1 like

Nymeria wrote:

fenix wrote:

You don't have right of way just by stepping out into the road. She couldn't have looked. A silly mistake. Are you suggesting that he hit her on purpose ? What cyclist would do that ? He's just as likely to be hurt if not more likely. His mistake was to ride a bike that wasn't legal on the road. If he's had the front brake he would probably still have hit her but at a lower speed and probably caused less harm. His mistake was also to be a nob after it.

 

She still has right of way... you might not like it but that is the law. If a child runs out into the road and a car hits them because they're driving too fast, the driver is in the wrong. It is no different for cyclists.

"It is illegal to obstruct the road. If somebody unlawfully assumes ownership of areas of a road, they are breaking the law. If a person, without lawful authority or excuse, in any way wilfully obstructs the free passage along a road, they are also guilty of an offence."

 

we are talking about a (allegedly) responsible adult establishing right of way over a bicycle riding teenager - the responsible way to do this would be to give clear signals and wait for the bicycle to stop before proceeding.

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davel replied to Nymeria | 6 years ago
5 likes
Nymeria wrote:

fenix wrote:

You don't have right of way just by stepping out into the road. She couldn't have looked. A silly mistake. Are you suggesting that he hit her on purpose ? What cyclist would do that ? He's just as likely to be hurt if not more likely. His mistake was to ride a bike that wasn't legal on the road. If he's had the front brake he would probably still have hit her but at a lower speed and probably caused less harm. His mistake was also to be a nob after it.

 

She still has right of way... you might not like it but that is the law. If a child runs out into the road and a car hits them because they're driving too fast, the driver is in the wrong. It is no different for cyclists.

This is starting to get a bit tricky, now, eh? You might want to read some other posts on this that have covered these scenarios with a lot more consideration.

But here's a few starter hints:
- The victim wasn't a child: it was an adult woman - a mother with children of her own, no less
- The vehicle wasn't a speeding car: it was a bike likely travelling around 10mph when it hit her.

If you have a point worth making, go for it.

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burtthebike replied to Nymeria | 6 years ago
0 likes

Nymeria wrote:

fenix wrote:

You don't have right of way just by stepping out into the road. She couldn't have looked. A silly mistake. Are you suggesting that he hit her on purpose ? What cyclist would do that ? He's just as likely to be hurt if not more likely. His mistake was to ride a bike that wasn't legal on the road. If he's had the front brake he would probably still have hit her but at a lower speed and probably caused less harm. His mistake was also to be a nob after it.

 

She still has right of way... you might not like it but that is the law. If a child runs out into the road and a car hits them because they're driving too fast, the driver is in the wrong. It is no different for cyclists.

Great to know that, thanks.  So where are all the reports of drivers being prosecuted for hitting pedestrians who have blindly stepped out front of them?  I can recall lots of cases where a pedestrian has stepped into the road without looking, been struck by a car, and the driver has either not been prosecuted or found not guilty of any crime.

If what you say is true, perhaps you ought to get in touch with the police and CPS, as they seem to be getting it wrong all the time.

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Nymeria | 6 years ago
0 likes

Doesn't matter if she was dancing in the middle of the road. She had right of way. If he had time to yell at her, he had time to take evasive action.

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beezus fufoon replied to Nymeria | 6 years ago
4 likes

Nymeria wrote:

Doesn't matter if she was dancing in the middle of the road. She had right of way. If he had time to yell at her, he had time to take evasive action.

read the story - he did take evasive action, she jumped back into his path

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zanf | 6 years ago
7 likes

Most of the comments on here are just plain fucking drivel and not worth the effort to replying to.

Shitty police 'forensic evidence' that has less science than a creationist climate denier can muster.

If she had been hit by a car or bus, you wouldnt even have known her name, let alone there even have been a prosecution

The majority of people have fallen for the pantomime without realising that this is going to be used to beat all cyclists over the head with it, and a lot of you are (and will be willingly) complicit with helping those who will use it.

It was a fucking show trial but most are too dumb to see that. Brought by a CPS that refuses to prosecute the seemingly most air tight cases against drivers, backed by a police force that has repeatedly refused to do anything about repeated incidents of substandard and dangerous driving.

There is an underlying reason this case was brought to trial, and spcifically why it was brought ot crown court, instead of dealt at magistrates as it would have been under any other circumstances. Just as there was a specific reason the 'grieving husband' was lined up for endless interviews on mainstream media.

Its a shit show frankly and a lot of people are now covered in it.

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RedfishUK | 6 years ago
0 likes

Interesting comments from a legal perspective from "the Cycling Lawyer"

 

http://thecyclingsilk.blogspot.co.uk/2017/08/the-alliston-mis-trial.html

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jigr69 | 6 years ago
0 likes

Taken from another website:

 

What brakes do you need on your bike?

As a general rule, if you ride a normal bike, you have to have two independent braking systems: one “which operates on the front wheel”, and one which operates on the back. (PCCUR r. 7(1)(b)(ii))

Alternatively, if you ride certain special kinds of bike, the rules can be different:

By law, fixed-wheel bikes (i.e. bikes where “one or more of the wheels is incapable of rotating independently of the pedals”) have to have a front brake. (PCCUR r. 7(1)(b)(i))

Tricycles which aren’t adapted for carrying goods still need to have two independent braking systems, but it’s acceptable to have both brakes operating on the single wheel (whether it’s at the back or the front). (PCCUR r. 9(2))

 Other bikes with more than two wheels (i.e. tricycles which are adapted for carrying goods, or bikes with more than three wheels): if there are two or more wheels on the front, the front brake has to operate on at least two of the front wheels. If there are multiple wheels at the back, the back brake has to operate on at least two of the back wheels. (PCCUR r. 7(1)(b)(ii))

Children’s bikes: the two-brake rule only applies to bikes where the saddle is 635mm or more above the ground (when the bike is upright, the saddle is raised to the fullest extent compatible with safety and the tyres are fully inflated). A child’s bike where the saddle is lower than 635mm only needs one braking system (which can be on either wheel). (PCCUR r. 7(1)(a) and (b), (2))

 Penny farthings etc: where the bike is constructed so that “the pedals act on any wheel or on the axle of any wheel without the interposition of any gearing or chain”, none of the braking requirements apply – so it seems that they can be ridden without brakes. (PCCUR r. 9(1)(a))

 This means that fixies with no front brake are technically illegal. So are adult dutch-style bikes which have ‘pedal backwards’ brakes on the rear wheel, but no separate brake on the front wheel.

As for recumbent bikes, the position is not entirely clear. As I’ve said, bikes are exempt from the requirement for two brakes (so it’s sufficient just to have one) if the highest part of the seating area of the saddle is below 635mm from the ground (which is generally the case for small children’s bikes). Presumably lots of recumbents will put the rider less than 635mm from the ground; but they also often have tall seat backs, which might stretch higher than 635mm above the ground. So it depends what “the seating area” means. There seems to be a good argument that the ‘chair back’ in a recumbent probably does count as part of the “seating area of the saddle”, so that you have to measure to the top of the chair – and if that’s more than 635mm above ground, you need brakes on both wheels. But it’s not entirely clear cut.

The rules for e-bikes (or “electrically assisted pedal cycles”) are different – I’ll look at e-bikes separately in the future.

Brake maintenance

The law also requires you to keep your brakes in efficient working order. (PCCUR r. 10(1))

There doesn’t seem to be any compulsory stopping distance or other standard test, so this is likely to be a matter of judgment. But your brakes will automatically fail the efficient working order test if they operate directly on any pneumatic tyre. So your brake pads mustn’t touch your tyres (unless you come within the exception for a bike with four or more wheels, none of which is bigger than 25cms). (PCCUR r. 10(2))

Inspections

A constable in uniform has the power to test and inspect your bike to see if your brakes comply with the rules. The inspection can be carried out on a road, or on other premises if the bike has been involved in an accident (so long as the inspection is carried out within 48 hours of the accident, and the owner of the premises consents). (PCCUR r. 11)

As I’ve said before, if you’re cycling on the road, a constable in uniform can require you to stop. If you refuse to stop when he demands, you’ll commit an offence and can be given a fixed penalty notice. If you do stop, but refuse to cooperate with a bike inspection, there would seem to be a good chance of some kind of offence of obstruction. (RTA s. 163(2), (3); RTOA ss. 51, 52, 54, Sch 3)

Avatar
davsear | 6 years ago
1 like

I think a lot of people are missing the point here. Whether he could have stopped in 3m or 12m, having a front brake fitted would have undoubtedly slowed and softened the impact between cyclist and pedestrian and this whole situation could have been avoided. That to me is what the police video highlights.  

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don simon fbpe replied to davsear | 6 years ago
1 like

davsear wrote:

I think a lot of people are missing the point here. Whether he could have stopped in 3m or 12m, having a front brake fitted would have undoubtedly slowed and softened the impact between cyclist and pedestrian and this whole situation could have been avoided. That to me is what the police video highlights.  

Are you saying that you could have predicted the injuries/result had Alliston been moving at a lower speed?

Who could have predicted a death at 18mph?

This wasn't an accident (both could have done something to avoid it), but the consequences couldn't have been predicted though. Nor could they have at 15mph, 10mph or even 0.0001mph.

Point not missed.

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jigr69 | 6 years ago
1 like

If the prosecution are correct in saying that the deceased was 6.35 metres away from the cyclists when she stepped out into the road, the thinking distance alone at 20mph is 6 metres. So if we call it 5.35 metres from 18mph, gives the guy 1 metre braking distance. Even by the Police standards, he still would have hit the woman at some speed.

It took the Police 3.1 metres from 15mph to stop, so 5mph per metre. In the one metre he had to stop, he reduced his speed by up to 8mph and by a minimum of 4mph. This is entirely in line with the results of the Police video using two brakes.

He wasn't cycling a defective bike which has been mentioned when it comes to comparing cars and bikes, the bike was perfectly okay. It wasn't appropriate nor legal to be on the road as the law states that a bike needs two means of stopping, although there are caveats. For example, you can ride a penny farthing legally on the road without any brakes, but if you have a trike, the rear brake must act upon both rear wheels. However for a recumbent bike, the rules are unclear as the need for two brakes is designated by the height of the seat (needs to be above 635mm above the ground). Who reading this knew that?

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Rich_cb replied to jigr69 | 6 years ago
0 likes
jigr69 wrote:

If the prosecution are correct in saying that the deceased was 6.35 metres away from the cyclists when she stepped out into the road, the thinking distance alone at 20mph is 6 metres. So if we call it 5.35 metres from 18mph, gives the guy 1 metre braking distance. Even by the Police standards, he still would have hit the woman at some speed.

It took the Police 3.1 metres from 15mph to stop, so 5mph per metre. In the one metre he had to stop, he reduced his speed by up to 8mph and by a minimum of 4mph. This is entirely in line with the results of the Police video using two brakes.

He wasn't cycling a defective bike which has been mentioned when it comes to comparing cars and bikes, the bike was perfectly okay. It wasn't appropriate nor legal to be on the road as the law states that a bike needs two means of stopping, although there are caveats. For example, you can ride a penny farthing legally on the road without any brakes, but if you have a trike, the rear brake must act upon both rear wheels. However for a recumbent bike, the rules are unclear as the need for two brakes is designated by the height of the seat (needs to be above 635mm above the ground). Who reading this knew that?

He had time to shout out twice before the impact therefore he had time to brake.

The bike may have been 'OK' by your definition but it was illegal and incapable of stopping as quickly as an equivalent legal bicycle.

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jigr69 replied to Rich_cb | 6 years ago
1 like

Rich_cb wrote:

He had time to shout out twice before the impact therefore he had time to brake. The bike may have been 'OK' by your definition but it was illegal and incapable of stopping as quickly as an equivalent legal bicycle.

The bike was perfectly okay in any sense of the definition, but wasn't legal to be where it was, don't think any disputes that fact. That is something that everyone agrees on. The guy is also an idiot for doing so, likewise his comments afterwards didn't help the situation.

Muscles take longer to react and enact than a mouth does to say anything. 

When cycling and driving if an obstacle suddenly appears infront of you, your first thought is, can I avoid it. If you cannot avoid it, then stopping and hoping for the best is the next and last resort. That is called the reaction time since in the process of that thinking etc, you car or bike is still moving forward.

If he had a front brake, he would still have to move his hands onto the brake after his thought process had gone through the process. A roadie on the tops or drops would have to do the same.

Have you ever seem two people walking down the street, try to avoid each other and end up bumping into each other? They didn't just stop dead, but tried to avoid the issue by going around the obstacle, if the other person does precisely the same but in the opposite direction, you are still on a collision course. Sometimes this happens two or three times with one person normally commenting about having a dance.

He saw the deceased, tried to avoid her by going on the inside of her, between kerb and her, but she stepped back and they collided. A tragic accident, yes. An unavoidable one, I don't think so. 

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Rich_cb replied to jigr69 | 6 years ago
0 likes
jigr69 wrote:

The bike was perfectly okay in any sense of the definition, but wasn't legal to be where it was, don't think any disputes that fact. That is something that everyone agrees on. The guy is also an idiot for doing so, likewise his comments afterwards didn't help the situation.

Muscles take longer to react and enact than a mouth does to say anything. 

When cycling and driving if an obstacle suddenly appears infront of you, your first thought is, can I avoid it. If you cannot avoid it, then stopping and hoping for the best is the next and last resort. That is called the reaction time since in the process of that thinking etc, you car or bike is still moving forward.

If he had a front brake, he would still have to move his hands onto the brake after his thought process had gone through the process. A roadie on the tops or drops would have to do the same.

Have you ever seem two people walking down the street, try to avoid each other and end up bumping into each other? They didn't just stop dead, but tried to avoid the issue by going around the obstacle, if the other person does precisely the same but in the opposite direction, you are still on a collision course. Sometimes this happens two or three times with one person normally commenting about having a dance.

He saw the deceased, tried to avoid her by going on the inside of her, between kerb and her, but she stepped back and they collided. A tragic accident, yes. An unavoidable one, I don't think so. 

You do know that speech involves the use of muscles right?

It is a far more complex process to form and vocalise words than to simply move a limb.

If he had a brake he should have been covering it in that situation anyway.

Even if he wasn't the time taken to move his hand on to the brake and use it would be far less than the time taken to shout out a warning.

Regardless he had time to shout out twice and he had time to begin braking, had he had legal brakes he would have reduce his speed far more effectively and the lady may well still be alive.

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BehindTheBikesheds replied to jigr69 | 6 years ago
0 likes

jigr69 wrote:

Rich_cb wrote:

He had time to shout out twice before the impact therefore he had time to brake. The bike may have been 'OK' by your definition but it was illegal and incapable of stopping as quickly as an equivalent legal bicycle.

The bike was perfectly okay in any sense of the definition, but wasn't legal to be where it was, don't think any disputes that fact. That is something that everyone agrees on. The guy is also an idiot for doing so, likewise his comments afterwards didn't help the situation.

Muscles take longer to react and enact than a mouth does to say anything. 

When cycling and driving if an obstacle suddenly appears infront of you, your first thought is, can I avoid it. If you cannot avoid it, then stopping and hoping for the best is the next and last resort. That is called the reaction time since in the process of that thinking etc, you car or bike is still moving forward.

If he had a front brake, he would still have to move his hands onto the brake after his thought process had gone through the process. A roadie on the tops or drops would have to do the same.

Have you ever seem two people walking down the street, try to avoid each other and end up bumping into each other? They didn't just stop dead, but tried to avoid the issue by going around the obstacle, if the other person does precisely the same but in the opposite direction, you are still on a collision course. Sometimes this happens two or three times with one person normally commenting about having a dance.

He saw the deceased, tried to avoid her by going on the inside of her, between kerb and her, but she stepped back and they collided. A tragic accident, yes. An unavoidable one, I don't think so. 

As I described elsewhere, the time it takes for the physical pulling of the brake (or pushing of the brake pedal in a motorvehicle) is 'mechanical action' time. This is totally ignored by pretty much everyone, that and the multiple thought processes (not just one) and why the not having a front brake/not having enough time to brake to a complete stop was  actually accurate.

mickey poor defence lawyer, not having your owen expert and accepting spurious evidence from the prosecution/police is all part and parcel of the outcome.

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TriTaxMan | 6 years ago
3 likes

I think the police video is significantly flawed.

Having been involved in an accident on my road bike, where a car pulled out of a junction in front of me and I was doing 18.4mph(according to my Garmin) when the car pulled out of a junction ahead of me, I would reckond the car was about 5m in front of me when they pulled out of the junction.

I had been covering the brakes as I had spotted the car at the junction, yet despite this fact, and the fact that my bike had two working brakes.  I had enough time to shed a few mph of speed but still struck the side of the car with enough force to split the frame of my bike in 3 places.

As many people have commented the correct tests should have been a fixie with a front brake and without a front brake, with the same size of rider and the same tyres under the same road conditions.  That's before you get into the nuances of low end brake calipers and blocks vs high end calipers and blocks.

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ooldbaker | 6 years ago
4 likes

If the speed of the cyclist was 10-14mph on collision i would be interested to hear the statistics for how many such collisions result in a fatality. I heard that only 20% of collisions with cars at 20mph are fatal so with a bike at half the speed I would think it would be incredibly low.

The police experiments (despite their obvious flaws) seem to show that:

a) the cyclist's decision to ride a modified bike was no worse than the motorists decision to ride at 20mph in the 30mph zone in a fully equiped car.

b) leaving that decision aside he did remarkably well to get the speed down as much as he did.

If you consider the high number of such bikes supposedly on the London streets. (I've never seen one in Dorset) If it was as reckless as the prosecution seem to say there would be a long queue of such cases to try. It clearly is not the problem they claim.

Whilst one fatality is a tragedy. If you mix pedestrains cycles and motors in one zone there will always be casualties.

There is an offence of riding an unroadworthy bike, he is guilty of that. Personally I think that is all. To prosecute further for the fatality is holding cyclists to a far higher standard than is demanded of other road users.

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Yorkshire wallet | 6 years ago
5 likes

Almost got divorced over this business last night. Wife told me that she thinks cyclists are going too fast through our town and I said what as opposed to cars going 10-15mph faster and weighing 20x more combined weight? She can't really substantiate anything, just ' feels' cyclists are going too fast, I counter, she gets strop on as I'm a know it all cyclist.

I told her that as a driver, a motorcyclist, a pedestrian and a cyclist - I feel the least safe as a cyclist. Deaf ears.

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madcarew | 6 years ago
8 likes

This is simply a tragic accident.

It is deeply unlikely that the speed Alliston hit Mrs Briggs contributed to her fatal injury. It seems very unlikely that even with a front brake that he would have avoided her.  Mrs Briggs injury was a fatal head injury caused largely by the speed and angle of her head hitting the ground from a fall. My friend's mother died 2 years ago after slipping on her bottom step and her head hitting the edge of the stairs. This caused a non-reversible head injury and she died 2 days later in hospital. From certain angles human heads are rather delicate (something that helmets try to assist with), and although Alliston hitting her certainly caused the fall, it is almost certain that there is almost nothing about Alliston's speed that caused the fatal injury. 

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Rich_cb replied to madcarew | 6 years ago
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madcarew wrote:

This is simply a tragic accident.

It is deeply unlikely that the speed Alliston hit Mrs Briggs contributed to her fatal injury. It seems very unlikely that even with a front brake that he would have avoided her.  Mrs Briggs injury was a fatal head injury caused largely by the speed and angle of her head hitting the ground from a fall. My friend's mother died 2 years ago after slipping on her bottom step and her head hitting the edge of the stairs. This caused a non-reversible head injury and she died 2 days later in hospital. From certain angles human heads are rather delicate (something that helmets try to assist with), and although Alliston hitting her certainly caused the fall, it is almost certain that there is almost nothing about Alliston's speed that caused the fatal injury. 

Complete nonsense.

If he hit her at 0.0001 mph do you think the outcome would have been the same?

Of course it wouldn't.

Therefore the speed he hit her at was a factor.

All the data on RTCs show that your chance of surviving a collision is inversely proportional to the speed that speed that the collision occurs at.

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madcarew replied to Rich_cb | 6 years ago
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Rich_cb wrote:
madcarew wrote:

This is simply a tragic accident.

It is deeply unlikely that the speed Alliston hit Mrs Briggs contributed to her fatal injury. It seems very unlikely that even with a front brake that he would have avoided her.  Mrs Briggs injury was a fatal head injury caused largely by the speed and angle of her head hitting the ground from a fall. My friend's mother died 2 years ago after slipping on her bottom step and her head hitting the edge of the stairs. This caused a non-reversible head injury and she died 2 days later in hospital. From certain angles human heads are rather delicate (something that helmets try to assist with), and although Alliston hitting her certainly caused the fall, it is almost certain that there is almost nothing about Alliston's speed that caused the fatal injury. 

Complete nonsense. If he hit her at 0.0001 mph do you think the outcome would have been the same? Of course it wouldn't. Therefore the speed he hit her at was a factor. All the data on RTCs show that your chance of surviving a collision is inversely proportional to the speed that speed that the collision occurs at.

It's not complete nonsense. I provided a simple example where someone wasn't struck with a bicycle but died from (effectively) the same injury. He caused her to fall. His speed (and I quote, so you can read it carefully and take the time to understand) "it is almost certain that there is almost nothing about Alliston's speed that caused the fatal injury. "

In this case, yes. He could have hit her at .00001 mph. He could have been laying down in front of her, stopped, she tripped, fell and received exactly the same injury. The fall caused her injury (almost certainly). Him running in to her caused the fall. Yes, in RTC the injury is (generally) proportional to the speed squared. This is not true of pedestrians striking pedestrians, or, across the board, of cyclists striking pedestrians. The mechanics are largely different to motor vehicle collisions, which are, of course the largest data set.

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Rich_cb replied to madcarew | 6 years ago
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madcarew wrote:

It's not complete nonsense. I provided a simple example where someone wasn't struck with a bicycle but died from (effectively) the same injury. He caused her to fall. His speed (and I quote, so you can read it carefully and take the time to understand) "it is almost certain that there is almost nothing about Alliston's speed that caused the fatal injury. "

In this case, yes. He could have hit her at .00001 mph. He could have been laying down in front of her, stopped, she tripped, fell and received exactly the same injury. The fall caused her injury (almost certainly). Him running in to her caused the fall. Yes, in RTC the injury is (generally) proportional to the speed squared. This is not true of pedestrians striking pedestrians, or, across the board, of cyclists striking pedestrians. The mechanics are largely different to motor vehicle collisions, which are, of course the largest data set.

It's still nonsense.

Even if it was the fall that killed her (I've not read a single report that states this) the likelihood of her falling and the likelihood of the fall injuring her both increase with the speed of the collision.

The more energy involved in a crash the more likely injury is to occur. Energy is proportional to the square of velocity so speed is the crucial factor here.

To try and dissociate the speed of the collision from the injuries suffered is patently ridiculous.

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hawkinspeter replied to madcarew | 6 years ago
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madcarew wrote:

This is simply a tragic accident.

It is deeply unlikely that the speed Alliston hit Mrs Briggs contributed to her fatal injury. It seems very unlikely that even with a front brake that he would have avoided her.  Mrs Briggs injury was a fatal head injury caused largely by the speed and angle of her head hitting the ground from a fall. My friend's mother died 2 years ago after slipping on her bottom step and her head hitting the edge of the stairs. This caused a non-reversible head injury and she died 2 days later in hospital. From certain angles human heads are rather delicate (something that helmets try to assist with), and although Alliston hitting her certainly caused the fall, it is almost certain that there is almost nothing about Alliston's speed that caused the fatal injury. 

I'm puzzled why there's no-one calling for mandatory helmets for pedestrians. Never mind the brakes on the bike - a helmet would have saved her life!

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Mungecrundle | 6 years ago
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Not come to a complete stop at every potential situation, but certainly reducing to a speed where a complete stop is an option should the potential situation develop into one that requires such action. This is a basic duty of care around other road users.

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BehindTheBikesheds replied to Mungecrundle | 6 years ago
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Mungecrundle wrote:

Not come to a complete stop at every potential situation, but certainly reducing to a speed where a complete stop is an option should the potential situation develop into one that requires such action. This is a basic duty of care around other road users.

Except in real life that rarely ever happens does it?

Do you reduce your speed to say 10mph for every junction, every footway/footpath, roundabout, that woman with a pram  is standing 20 metres away, that child with a football exiting the park a good 10m from the crossing  or every time a pedestrian looks like they might cross, what about out of town, do you slow to 10mph for every farmers gate/entrance, every unsighted bend in the road, if not why not?

Because you've just said that you should slow to a speed that you might be able to come to a complete stop should the unexpected happened (and we are talking last few seconds in fron of you right), or can you stop from say 18mph in less than 3 metres when the unexpected occurs and thus by doing so break the laws of physics as was proposed by the prosecution???

How slow must one slow to for each and every situation I've described and others beside, which bike type, rider weight, brake type, rider age (because older people have slower reactions as we know) do you ascribe that for, what about an old side pull braked bike,  ridden by a 120kg elderly male,  should that mean one slows to 5mph in case little miss steps out a few metres in front or a tractor potentially pulls out of  a farmers track. C'mon, please let us know these speeds and for which scenario and which type of bike, brake, person?

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Mungecrundle replied to BehindTheBikesheds | 6 years ago
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BehindTheBikesheds wrote:

Mungecrundle wrote:

Not come to a complete stop at every potential situation, but certainly reducing to a speed where a complete stop is an option should the potential situation develop into one that requires such action. This is a basic duty of care around other road users.

Except in real life that rarely ever happens does it?

Do you reduce your speed to say 10mph for every junction, every footway/footpath, roundabout, that woman with a pram  is standing 20 metres away, that child with a football exiting the park a good 10m from the crossing  or every time a pedestrian looks like they might cross, what about out of town, do you slow to 10mph for every farmers gate/entrance, every unsighted bend in the road, if not why not?

Because you've just said that you should slow to a speed that you might be able to come to a complete stop should the unexpected happened (and we are talking last few seconds in fron of you right), or can you stop from say 18mph in less than 3 metres when the unexpected occurs and thus by doing so break the laws of physics as was proposed by the prosecution???

How slow must one slow to for each and every situation I've described and others beside, which bike type, rider weight, brake type, rider age (because older people have slower reactions as we know) do you ascribe that for, what about an old side pull braked bike,  ridden by a 120kg elderly male,  should that mean one slows to 5mph in case little miss steps out a few metres in front or a tractor potentially pulls out of  a farmers track. C'mon, please let us know these speeds and for which scenario and which type of bike, brake, person?

Pretty much right in principal, though as usual you extrapolate to absurdity. I can give you two recent instances where I have felt the need to reduce speed to significantly below the posted limit.

First scenario, 30 mph urban road, driving. I see a middle aged bloke pursuing a small girl on a bicycle with stabilizers across some grass and towards the curb. I can see he is going to catch her in time but cover the brakes anyway then I see a second small girl legging it at another angle towards the road, she looks to be about 3 years old and there is no other adult in proximity. I stop the car, ready to get out and intercede if necessary. Dad has now caught first wayward daughter, looks up and shouts to second daughter. She doesn't go into the road.

Scenario 2. End of club ride, I turn into the High Street and see spotty youth. Pair of cans over head, red bull in hand angling towards what I know to be a popular crossing point for peds to the park opposite. I slow, I shout "Oi oi!" as he starts to cross but without much hope that he will hear me I slow to walking pace as he wanders across the road without so much as a glance in my direction.

It's an accumulation of experience, as you allude to, every journey throws up a novel set of circumstances and permutations. Most peds don't just randomly jump off the pavement. Most drivers don't just pull out without looking, but if you are observing what is going on around you then it becomes less challenging to anticipate the actions of other road users and be prepared. My personal standard is that nothing that occurs in your forward field of vision should really come as a surprise.

And to answer a specific challenge, if I was on a country road and came to a truly blind corner or junction, then yes I would slow to whatever speed was necessary to be able to stop within the distance I can see (a favourite phrase of yours I seem to recall whenever you go off on one about hi viz or cycle lights) even if that is 10mph.

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