Volkswagen Cleared by Coroner in Melissa Ryan "Unintended Deceleration" Case

[Candyman]

Maintaining it in daily driving might be one thing but when someone gets killed, the picture changes eh ... I am more than happy to back off when someone pulls in front of me and destroys my cushion

[The_Hawk]

Maintaining it in daily driving might be one thing but when someone gets killed, the picture changes eh ... I am more than happy to back off when someone pulls in front of me and destroys my cushion

Don't get me wrong, I'm not saying ride the idiot arse, just saying that generally speaking if there is a gap there will be some idiot who wants to fill it to get 5m further down the road. (also that whole keep left thing... people fail at that... and indicating...)

[JonP01]

so I don't know where the coroner got hers 2seconds for the truck travelling at 100km/h ?

Well if you apply pure physics calculations where you have a variable mass but a set coefficient of friction, you will actually find that stopping distance is not dependent upon mass. In other words, without considering anything else other than theoretical physics, a 60 tonne mass will stop in the same distance that a 1 tonne mass can. But that theory as I say assumes that a truck, for example, has exactly the same coefficient of friction as, say, a Golf GTI does and it also assumes that there is no delay between initialising the braking sequence and the commencement of retardation. Even taking into account tyre grip just as an example, I think it is very likely the coefficient of grip offered by a high performance tyre fitted to a hot hatch is superior to that on a truck where the emphasis is on durability, load carrying capability, resistance to damage and overall strength.

When I went for my heavy vehicle licences back in the 1980s (3A to 3B to 4B as they were back then in NSW), I recall that the NSW handbook at the time cited a gap of around 4 seconds on a flat road in dry conditions for a rigid truck. My licence entitled me to drive anything up to tourist coaches and did not cover articulated or B-doubles. There was yet another handbook back then for articulated licences so I don't know what the distances were in that handbook. After getting my heavy rigid licence I got a job driving for Australia Post. Australia Post were not one of those organisations who took anyone with a licence. You had to pass a specific Australia Post driving test in a heavy vehicle through the city and suburbs. Then you received further training in road craft and maintenance. I will tell you one thing. Be it at your peril if you even dreamt of keeping a gap less than 5 seconds in their trucks. They'd chuck you out and demote you to the ice cream vans quick smart.

Having had some years experience in driving heavy vehicles it is difficult to convey to the uninitiated how different they are to a car from 30 years ago, let alone the far better performing cars of today. Slowing down is a big deal and you can throw those theoretical physics equations out the window. The braking systems are entirely different, the braking feel is entirely different, you have a "lag" between your actions on the brake pedal and what happens at the wheels, you do not have the same sort of progressive feel or feedback that you get in a car and you've got all those extra wheels that can potentially slip and lose adhesion. You've got a massive weight transfer as the balance of the vehicle moves forward and the overall stability is nothing like what it is in any car. And if you are driving an articulated vehicle, you have to brake the trailer as well, not just the prime mover. And also don't forget that the vehicle is never going to respond in a consistent way. It takes a lot of skill as a truck driver to take your load and drive in consideration of that load, then drop the load off and suddenly you are 30 tonnes lighter. The brakes and everything are different all over again and it is really easy to lock the brakes up if you don't compensate correctly.

Add to all of that a level of vigilance required that is far beyond what you need in a car. In a car you don't have to worry about height, you don't have to worry about swiping cars in adjacent lanes, you don't have to worry about your width, you don't have to worry about grabbing extra lane widths to negotiate turns, you don't have to think ahead because of poor acceleration. All of these liabilities as a truck driver require constant scanning, both ahead and in the mirrors and forward planning. In a car you have an automatic gearbox or at worst you have a manual gearbox that has synchromesh and a nice, quick shift action on all forward gears. In many trucks, you have none of that. You have a gearbox that requires double declutching both on the way up and on the way down. Sure, many smaller trucks these days do come with synchromesh but any professional truck driver who does this successfully for a long term living will still tell you that the only way to make your driveline survive for the long haul and economically is to drive it as if it did not have synchromesh.

Before anyone even tries to suggest the Detective Sergeant Bellion is correct as regards a 2 second gap, they really need to do two things (apart from reading the remainder of my post). Firstly, they need to read the Victorian Truck and Bus Driver's Handbook, especially pages 44 to 59 which cover the areas that require vigilance and planning as previously mentioned. Then they need to be a passenger in a large articulated vehicle at the hands of a skilled professional driver, just so they can see what it is like, how the driver reacts to things and the types of gaps they leave when driving in the vicinity of other cars.

Now, turning our attention to the handbook, let's read what is says on page 50:

If you are driving a vehicle with airbrakes it can take up to one second after you press the brake pedal for the air to reach the brakes.

OK, that is up to one second gone out of Detective Bellion's "safe" 2 second allowance, because the truck that rammed into the back of the Golf had airbrakes. Would anyone like to dispute this because the air brake delay is not enacted into actual law and is only written in the handbook?

Now let's see what is says on page 46:

Use your mirrors often. Scan them and look back to the road. At 90 kmh you will travel 25 metres in one second. So keep each glance to no more than a second at a time.

OK, given that rules need to be made to cater for the lowest common denominator, we will take a second as a reasonable time to divert one's attention from the forward direction, scan and interpret what is happening in the rear view mirrors, then divert their gaze back in a forward direction.

So, if we had a scenario where we are in a heavy vehicle with airbrakes and the car ahead with that initial "safe" Victorian Police-endorsed 2 second gap, we have just lost 1 second if the car ahead begins to emergency stop just when we were starting our rear view mirror scan, as well as another second because of the airbrake delay. That just leaves reaction time. On page 15 of the Inquest Findings, Detective Sergeant Bellion himself indicates studies whereby reaction time prior to braking will be 1.5 seconds or less for 85% of the population. Again, because rules and regulations have to be made to cater for the lowest common denominator, we are now up to 3.5 seconds.

So far as the truck is concerned then, it has already travelled 92.36 metres at 95 kmh before the braking system even begins to retard the vehicle (26.39 metres lost during the rear view mirror scan, 39.58 metres lost due to reaction time and another 26.39 metres lost due to "lag" in the airbrake system). Now, assuming "perfect" physics in the sense that an articulated heavy vehicle can pull up in the same distance as a sports car being that they have equal friction coefficients of 0.8, then the truck travels another 44.38 metres before coming to a complete stop. Total distance travelled before stationary = 136.74 metres.

So far as the car ahead is concerned, we don't have to take into account reaction times, air brakes or looking in rear view mirrors for the car ahead. We don't take into account reaction time because the car ahead does not begin to actually slow down and decrease the gap to the vehicle behind until the brakes are actually retarding the car. We don't take into account time lost in the mirror because if the driver ahead is looking in the mirror, they are not registering a hazard ahead of them that prompts them to hit the brakes in the first place. And the car ahead has a normal hydraulic braking system, not an airbrake system, so the braking response is almost instantaneous.

So far as the car is concerned then, mash the brakes and you stop from 95 kmh in the same 44.38 metre stopping distance (because I am assuming a perfect "truck" here). Therefore, in the above scenario, the truck would stop 92 metres after the car has. That is one heck of an impact unless the truck manages to change lanes and avoid the car. Even if we assume the truck driver was not looking in his mirrors but ahead when the emergency situation began, he will still give the car ahead a mighty hard shove in the back if he could not change lanes.

So the 2 second gap theory is severely flawed. It assumes the driver of a truck has to have a reaction time substantially better than 85% of the population, it assumes the truck slows down as well as a car does, it assumes no delay in the airbrake system and it assumes the truck driver was not involved in mirror scanning or any other diversionary activities when the emergency occurs. The only time the 2 second gap theory is valid for a truck - by "valid" I mean where the front of the truck would not make contact with the car ahead - is where the truck driver hits his brakes less than 1 second after the car in front hits its brakes and where the truck stops in the same distance the car does. By Detective Sergeant Bellion's very own testimony, reaction times for most people are greater than 1 second and trucks do not stop as well as passenger cars.

This is why we have the table on page 51 of the handbook. It is there because that is what is required in the real world. The distances are almost 300% greater than what Detective Sergeant Bellion says are required, because they need to be that large in order to account for all possible emergency scenarios as well as take into account the mechanical differences between trucks and cars as well as the different techniques required to drive them.

[nat225]

I wonder if when talking stopping distances they take into account moving traffic, ie the idea that you are very unlikely to come across a completely stationary object so can take into account that the other object also had to slow down and stop.

As for maintaining distance, I challenge anyone to maintain *ANY* distance while in or around the major populations. I think if I tried to drive down the M5 in Sydney during the peak (or just about any time of day) while maintaining a 2-3 second gap, slowing if anyone pulled into that space, I'd just end up stopped in the middle of the road

2 seconds gap = 60 metres. never ever going to happen on M5 during day time!

as long as the traffic is flowing and the driver is paying attention to driving (not email, not facebook, not google map, not even on this forum ) when behind the steering wheel of a moving vehicle then any potential troubles should be kept at bay.

problem is that these days people are so addicted to phone. i read on the main page of the paper today, a female teenager from sunshine coast swerved her car onto the grass area off the road killed a person walking on the side of the road in her SUV while using her phone to check on google map (supposedly) hence she claimed she had not seen the now deceased fruit picker from Taiwan.

5 months later, she was back on driving and got caught using her phone while driving (no repentance? no lesson learnt?) .

[JonP01]

problem is that these days people are so addicted to phone. i read on the main page of the paper today, a female teenager from sunshine coast swerved her car onto the grass area off the road killed a person walking on the side of the road in her SUV while using her phone to check on google map (supposedly) hence she claimed she had not seen the now deceased fruit picker from Taiwan.

5 months later, she was back on driving and got caught using her phone while driving (no repentance? no lesson learnt?) .

I actually feel very divided loyalties over this case because of the implications of the mobile phone conversation. Yesterday, I was literally almost run over by a teenager in a White Toyota SUV - I was about to walk across a marked pedestrian crossing as my green "walk" light had just lit up. But as I looked to where the cars were coming from, this teenager just sped through - engrossed as he was with his mobile phone. After he passed me he looked out the window at me and just laughed. Yes, it really was hysterically funny - especially for me - and I am sure he would have been having a real belly laugh if someone had just started crossing the road without double-checking. Mind you, I always interpret the green walk signal as merely indicating that I have a legal right of way to cross the road and nothing more

When I am on the road, the only safe thing in my view is to be behind these people - if I see someone engaged in a mobile conversation behind me I will quietly attempt to change lanes and pull back behind them so long as it is safe and I do not impede anyone else's progress or safety gaps by doing that.

Sure, at the speeds we are talking about it would just mean rear end damage, but I don't want to scratch my lovely little white Polo

[Transporter]

I actually feel very divided loyalties over this case because of the implications of the mobile phone conversation. Yesterday, I was literally almost run over by a teenager in a White Toyota SUV - I was about to walk across a marked pedestrian crossing as my green "walk" light had just lit up. But as I looked to where the cars were coming from, this teenager just sped through - engrossed as he was with his mobile phone. After he passed me he looked out the window at me and just laughed. Yes, it really was hysterically funny - especially for me - and I am sure he would have been having a real belly laugh if someone had just started crossing the road without double-checking. Mind you, I always interpret the green walk signal as merely indicating that I have a legal right of way to cross the road and nothing more

When I am on the road, the only safe thing in my view is to be behind these people - if I see someone engaged in a mobile conversation behind me I will quietly attempt to change lanes and pull back behind them so long as it is safe and I do not impede anyone else's progress or safety gaps by doing that.

Sure, at the speeds we are talking about it would just mean rear end damage, but I don't want to scratch my lovely little white Polo

Did you report him? You should have.