Discussion
By far the most valuable skill a driver can learn is planning. An advanced student is taught a whole range of skills during a driving course - systematic driving, skid control, overtaking, cornering, etc, etc, but the one skill I want them to keep above everything else is their ability to make driving plans.
Roadcraft says that good observations allow a driver to make driving plans based on...
1. What you can see,
2. What you can't see and
3. What you can reasonably expect to happen
Number 1 is easy, and shouldn't need any further explanation, unless you're a taxi driver or my mate Andy, who can't drive for toffee.
Numbers 2 and 3, however, aren't as simple, and could do with a little expansion.
A good driver isn't just someone who can react to what's happening in front of them. Young drivers naturally have very fast reaction times, and so, if fast reaction times were a measure of driving ability, young drivers aged between 17 and 23 would have the lowest accident rates. I don't think I need to dig up any accident statistics to show that isn't the case, do I?
Even the best drivers only have an average reaction time - I remember reading that Michael Schumacher had his reactions tested a few years ago, and had basic reactions that were no quicker than any other Joe Soap of a similar age. Reaction times are just that - the time it takes a person to react to basic stimuli.
"So come on then Reg - stop mucking about - what does make a good driver then?" I hear you ask.
Two essential ingredients. An active imagination, and an ability to constantly ask yourself questions.
An active imagination is necessary in order to fulfil number 2 above - what you can't see. As you drive into a left-hand bend with a limited view, you can see lots of things - the limit point, the camber of the road, the condition of the road surface, the white line system, on-coming vehicles, etc, etc. What you can't see are the car that's parked in an awkward position just out of view, the cyclist going in your direction (which is also going to pass the parked car), the dog off it's lead, the bus coming in the opposite direction that will cut the corner, and Arnold Schwarzenegger in a Harrier jump-jet, who's about to land in the road.
All the things that are out of sight are the reason why the fourth principle of cornering is that you should always be able to stop on your own side of the road, in the distance you can see to be clear. But, having such a good imagination, you already knew that, didn't you?
The thing is, you have to be careful not to let your imagination run away with you. An over active imagination can be as much a hindrance as not having one at all. If you actually did think that Arnold was about to land after every corner, you'd never get above 5mph, and that would be bordering on tedious.
A good driver will combine their imagination with an ability to ask themselves questions as they go along. If there is a combination of parked car/cyclist/on-coming bus around this corner, what is my plan? Will I slow down and let them sort themselves out? can I safely pass the cyclist before I get to the car? Do the wheels on the bus go round and round?
The most important question I teach people to ask themselves as they drive along is "what's next?"
What am I going to do next? What is the next hazard? after this corner, what's the next one like? When I've completed this overtake, what's next? I don't need to go on - you get the idea.
Start asking yourself "the question", and you'll find that your attention is drawn further up the road and your planning skills will improve no end.
Roadcraft says that good observations allow a driver to make driving plans based on...
1. What you can see,
2. What you can't see and
3. What you can reasonably expect to happen
Number 1 is easy, and shouldn't need any further explanation, unless you're a taxi driver or my mate Andy, who can't drive for toffee.
Numbers 2 and 3, however, aren't as simple, and could do with a little expansion.
A good driver isn't just someone who can react to what's happening in front of them. Young drivers naturally have very fast reaction times, and so, if fast reaction times were a measure of driving ability, young drivers aged between 17 and 23 would have the lowest accident rates. I don't think I need to dig up any accident statistics to show that isn't the case, do I?
Even the best drivers only have an average reaction time - I remember reading that Michael Schumacher had his reactions tested a few years ago, and had basic reactions that were no quicker than any other Joe Soap of a similar age. Reaction times are just that - the time it takes a person to react to basic stimuli.
"So come on then Reg - stop mucking about - what does make a good driver then?" I hear you ask.
Two essential ingredients. An active imagination, and an ability to constantly ask yourself questions.
An active imagination is necessary in order to fulfil number 2 above - what you can't see. As you drive into a left-hand bend with a limited view, you can see lots of things - the limit point, the camber of the road, the condition of the road surface, the white line system, on-coming vehicles, etc, etc. What you can't see are the car that's parked in an awkward position just out of view, the cyclist going in your direction (which is also going to pass the parked car), the dog off it's lead, the bus coming in the opposite direction that will cut the corner, and Arnold Schwarzenegger in a Harrier jump-jet, who's about to land in the road.
All the things that are out of sight are the reason why the fourth principle of cornering is that you should always be able to stop on your own side of the road, in the distance you can see to be clear. But, having such a good imagination, you already knew that, didn't you?
The thing is, you have to be careful not to let your imagination run away with you. An over active imagination can be as much a hindrance as not having one at all. If you actually did think that Arnold was about to land after every corner, you'd never get above 5mph, and that would be bordering on tedious.
A good driver will combine their imagination with an ability to ask themselves questions as they go along. If there is a combination of parked car/cyclist/on-coming bus around this corner, what is my plan? Will I slow down and let them sort themselves out? can I safely pass the cyclist before I get to the car? Do the wheels on the bus go round and round?
The most important question I teach people to ask themselves as they drive along is "what's next?"
What am I going to do next? What is the next hazard? after this corner, what's the next one like? When I've completed this overtake, what's next? I don't need to go on - you get the idea.
Start asking yourself "the question", and you'll find that your attention is drawn further up the road and your planning skills will improve no end.
...and "What If?" is another catchphrase that clicks with people.
Some drivers just don't know how to use their imaginations suffiently, or more importantly - they aren't trained to use their curiosity, and don't know how to prioritise information from (1)
As you say, some people have good reactions but that's often too late to cope with a situation. Some experienced drivers cope with the unexpected much better, because it's no longer unexpected! Their experience (memory) has equipped them with a sense of déjà vu.
A quote from a diving instructor in the States: "...that they don't do enough training. You seem to equate lack of training and lack of experience. You can't teach experience. So exactly how do you remedy this? This is going to sound really arrogant; George Carlin said: 'Think of how stupid the average American is, then realize that half of them are stupider than that, because that's what average means.' It seems like some people around here want everyone to have a degree in theory before they get in a hot tub (yet the material to gain such understanding remains strangely rare). Besides, all the additional training in the world isn't going to stop the panic reflex when something goes south underwater."
This could apply equally to new and inexperienced drivers.
Rather than thinking of just 'what's next', I try to plan ahead to take in several 'what nexts', in an effort to keep the flow of the drive.
Some drivers just don't know how to use their imaginations suffiently, or more importantly - they aren't trained to use their curiosity, and don't know how to prioritise information from (1)
As you say, some people have good reactions but that's often too late to cope with a situation. Some experienced drivers cope with the unexpected much better, because it's no longer unexpected! Their experience (memory) has equipped them with a sense of déjà vu.
A quote from a diving instructor in the States: "...that they don't do enough training. You seem to equate lack of training and lack of experience. You can't teach experience. So exactly how do you remedy this? This is going to sound really arrogant; George Carlin said: 'Think of how stupid the average American is, then realize that half of them are stupider than that, because that's what average means.' It seems like some people around here want everyone to have a degree in theory before they get in a hot tub (yet the material to gain such understanding remains strangely rare). Besides, all the additional training in the world isn't going to stop the panic reflex when something goes south underwater."
This could apply equally to new and inexperienced drivers.
Rather than thinking of just 'what's next', I try to plan ahead to take in several 'what nexts', in an effort to keep the flow of the drive.
Experience and a 'good' imagination certainly help.
I often drive along and patter through what I'm seeing and just as importantly what I'm not seeing. "Country lane........fields.....ploughing this time of year......mud on roads.........approaching cottages........Thursday, pension day.......doddery old fart backing hisRover out to go to the post office......half term.......kids around at midday....." etc
Maybe if my car stereo worked I'd stop talking to myself but it's amazing how often it comes true.
I often drive along and patter through what I'm seeing and just as importantly what I'm not seeing. "Country lane........fields.....ploughing this time of year......mud on roads.........approaching cottages........Thursday, pension day.......doddery old fart backing hisRover out to go to the post office......half term.......kids around at midday....." etc
Maybe if my car stereo worked I'd stop talking to myself but it's amazing how often it comes true.
Edited by Flintstone on Sunday 25th February 01:15
R_U_LOCAL said:
All the things that are out of sight are the reason why the fourth principle of cornering is that you should always be able to stop on your own side of the road, in the distance you can see to be clear.
With this in mind, surely everyone should be tackling the twisty stuff on the average national speed limit country lane at well below 60? I would have thought that safe stopping distance on a bend is greater than at the same speed on the straight?
Blokko said:
R_U_LOCAL said:
All the things that are out of sight are the reason why the fourth principle of cornering is that you should always be able to stop on your own side of the road, in the distance you can see to be clear.
With this in mind, surely everyone should be tackling the twisty stuff on the average national speed limit country lane at well below 60? I would have thought that safe stopping distance on a bend is greater than at the same speed on the straight?
Only if you couldn't stop from 60mph in the distance you can see.
You're coming to a conclusion based on two misunderstandings.
1. You can't brake effectively when you're cornering
2. It's not safe to travel above the speed limit.
As for 1, it'd only be unsafe to brake if you were cornering at the absolute limit of the cars capabilities. There is a trade-off between steering, accelerating and braking, which all compete for tyre grip. There is only a finite amount of grip available for each of those activities, and the more you use up on one, the less amount you have available for another.
For example, if you use up 50% of your available tyre grip with braking, you've still got 50% of the grip left available for steering.
Anyone who's ever done a track day and cornered towards the edge of a cars handling capabilities will know that the amount of grip available for cornering, even in fairly mundane modern cars, is very high - high enough to make it idiotic to contemplate using all the cars cornering capabilities on anything other than the most open, visible corners.
Remember that we're talking about road driving here. We're not trying to shave a few tenths off a lap time, or a few seconds of a stage time - we're driving on the road, with all it's associated hazards. Corner briskly by all means - it's one of the greatest driving pleasures - but don't drive on the cars limit, as you've then nothing left if something goes wrong.
Braking in a corner is not a no-no. I advise that it should be avoided, but if something pulls out, or runs out, or in some other way puts you in danger, then I want you to brake. Hard. You'd be surprised how hard you can brake whilst cornering, and still maintain control of a car, and with modern systems like ABS, ESP, ASC, etc, becoming more common, your ability to brake whilst cornering, although not ideal, is getting much better.
Another point to consider is that braking distances in modern cars are far, far better than those stated in the highway code. That's not to say the HC braking distances should be disregarded - they take into account a worst case scenario - but believe me, an alert driver in a modern, well-maintained car, on a good, dry road surface, can easily, easily beat the highway code stopping distances.
Everyone should be given the opportunity to try out the braking capabilities of their car in a safe, off-road environment. It was always something I'd do with advanced students whilst teaching skid control, as it gave them far more confidence with that 4th cornering rule, in allowing them to realise just how quickly they can stop, and how that relates to the distance they can see to be clear. If you ever get the opportunity to try threshold braking in your own car in a safe environment, then I recommend that you do.
As for point 2 - I'm going to stick my neck out here and invite some criticism.
It's perfectly safe to travel above, and sometimes well above the national speed limit if you know what you're doing.
It's not legal, of course, and speaking corporately I can't recommend it...
But come on - When instructing, and when I'm working, I have a conditional exemption from speed limits, and I've driven, perfectly safely, at speeds which would make some people's eyes water. I wouldn't do that if it weren't safe, as I want to go home to my family and my tea.
If you choose to do it yourself, that's up to you, but always remember that basic safe stopping rule...
Always be able to stop on your own side of the road, in the distance you can see to be clear.
Edited by R_U_LOCAL on Monday 26th February 00:59
R_U_LOCAL said:
For example, if you use up 50% of your available tyre grip with braking, you've still got 50% of the grip left available for steering.
Actually that's wrong - it's not a simple linear sum, i.e. braking grip + cornering grip doesn't equal 100%. It's the sum of the squares that add up to coefficient of friction x weight. If you're braking at 0.5g (and assuming a friction coefficient of 1.0 - pretty reasonable for normal road tyres on a dry road), you can still generate 0.87g cornering.
Of course, accessing all of that isn't necessarily easy...
StressedDave said:
R_U_LOCAL said:
For example, if you use up 50% of your available tyre grip with braking, you've still got 50% of the grip left available for steering.
Actually that's wrong - it's not a simple linear sum, i.e. braking grip + cornering grip doesn't equal 100%. It's the sum of the squares that add up to coefficient of friction x weight. If you're braking at 0.5g (and assuming a friction coefficient of 1.0 - pretty reasonable for normal road tyres on a dry road), you can still generate 0.87g cornering.
Of course, accessing all of that isn't necessarily easy...
Are you Comic Book Guy off the Simpsons?
R_U_LOCAL said:
StressedDave said:
R_U_LOCAL said:
For example, if you use up 50% of your available tyre grip with braking, you've still got 50% of the grip left available for steering.
Actually that's wrong - it's not a simple linear sum, i.e. braking grip + cornering grip doesn't equal 100%. It's the sum of the squares that add up to coefficient of friction x weight. If you're braking at 0.5g (and assuming a friction coefficient of 1.0 - pretty reasonable for normal road tyres on a dry road), you can still generate 0.87g cornering.
Of course, accessing all of that isn't necessarily easy...
Are you Comic Book Guy off the Simpsons?
Err.........Jeff Albertson he is not.
vonhosen said:
R_U_LOCAL said:
StressedDave said:
R_U_LOCAL said:
For example, if you use up 50% of your available tyre grip with braking, you've still got 50% of the grip left available for steering.
Actually that's wrong - it's not a simple linear sum, i.e. braking grip + cornering grip doesn't equal 100%. It's the sum of the squares that add up to coefficient of friction x weight. If you're braking at 0.5g (and assuming a friction coefficient of 1.0 - pretty reasonable for normal road tyres on a dry road), you can still generate 0.87g cornering.
Of course, accessing all of that isn't necessarily easy...
Are you Comic Book Guy off the Simpsons?
Err.........Jeff Albertson he is not.
Well, I'm afraid that's not the sort of calculation I want to be making as I hurtle towards the scenery.
The old tyre-grip trade off will do me nicely thank you.
My interest is more involved in simplifying a very complex set of circumstances, each of which could be explained with equations of varying complexity, down to a basic theory which makes students think carefully about how much tyre grip they're using on various aspects of driving, and what could happen if they're daft enough to reach a cars limit of grip on the road.
If I gave your equation to a room full of bobbies and squaddies, they'd look at me like I was from another planet.
KISS
Keep It Simple Stupid.
If I gave your equation to a room full of bobbies and squaddies, they'd look at me like I was from another planet.
KISS
Keep It Simple Stupid.
R_U_LOCAL said:
My interest is more involved in simplifying a very complex set of circumstances, each of which could be explained with equations of varying complexity, down to a basic theory which makes students think carefully about how much tyre grip they're using on various aspects of driving, and what could happen if they're daft enough to reach a cars limit of grip on the road.
If I gave your equation to a room full of bobbies and squaddies, they'd look at me like I was from another planet.
KISS
Keep It Simple Stupid.
If I gave your equation to a room full of bobbies and squaddies, they'd look at me like I was from another planet.
KISS
Keep It Simple Stupid.
I used to have to teach it to Police accident investigators (mind you using that term dates me!) - draw the friction circle rather than using numbers and it's a piece of the proverbial to understand. I know PCs really, really don't want to do maths, and most of them are visual learners. I'm with Einstein on this - make it as simple as possible but no simpler. Turning the friction circle into a diamond means you remove all the circumstances they really, really need to know about.
FWIW, I do a lot of datalogging on road and in general, nobody goes over 0.5g sideways (limits of visibility rather than adhesion being the practical limit), or at least not more than once
""With this in mind, surely everyone should be tackling the twisty stuff on the average national speed limit country lane at well below 60? I would have thought that safe stopping distance on a bend is greater than at the same speed on the straight? ""
One of my mantras...to myself and to Associates...
""Speed to vision"" - they get sick of hearing it at first I suppose...but eventually it might stick?
bof.
One of my mantras...to myself and to Associates...
""Speed to vision"" - they get sick of hearing it at first I suppose...but eventually it might stick?
bof.
StressedDave said:
FWIW, I do a lot of datalogging on road and in general, nobody goes over 0.5g sideways (limits of visibility rather than adhesion being the practical limit), or at least not more than once
Come and have a ride out with me one day then.
Overall it's a fascinating subject, and some of the more complicated accident investigation reports that I've recieved for my fatal accidents have been a very interesting read.
It's just a shame I can't find a simple, straightforward way to explain how to "feel" what a car is doing. It's a bit like walking - we all know how we do it, but explaining it is nigh on impossible.
R_U_LOCAL said:
For example, if you use up 50% of your available tyre grip with braking, you've still got 50% of the grip left available for steering.
Reg, I find much to admire in your contributions and desire for simplicity. But StressedDave does have a point to make, based on sound reasoning and much experience, and it's worth considering. Forum discussions can decline into pedancy, but if you're going to present figures it's worthwhile checking them for sense.
R_U_LOCAL said:
Braking in a corner is not a no-no. I advise that it should be avoided, but if something pulls out, or runs out, or in some other way puts you in danger, then I want you to brake. Hard. You'd be surprised how hard you can brake whilst cornering, and still maintain control of a car, and with modern systems like ABS, ESP, ASC, etc, becoming more common, your ability to brake whilst cornering, although not ideal, is getting much better.
I think this is overly simplistic - StressedDave's cryptic comment about "accessing" grip appears especially relevant. If you're pressing on in a new 5 series and stand on the brakes mid corner, you'll likely stop undramatically and unaware of the electronics' contribution to your safety and wellbeing. If you were to try the same in an old Carrera you would likely find yourself an unwitting participant in a dramatic demonstration of the influence of weight transfer. The manner in which you brake hard can be pivotal (very bad pun intended).
R_U_LOCAL said:
Everyone should be given the opportunity to try out the braking capabilities of their car in a safe, off-road environment. It was always something I'd do with advanced students whilst teaching skid control, as it gave them far more confidence with that 4th cornering rule, in allowing them to realise just how quickly they can stop, and how that relates to the distance they can see to be clear. If you ever get the opportunity to try threshold braking in your own car in a safe environment, then I recommend that you do.
As for point 2 - I'm going to stick my neck out here and invite some criticism.
It's perfectly safe to travel above, and sometimes well above the national speed limit if you know what you're doing. [...] If you choose to do it yourself, that's up to you, but always remember that basic safe stopping rule...
Always be able to stop on your own side of the road, in the distance you can see to be clear.
As for point 2 - I'm going to stick my neck out here and invite some criticism.
It's perfectly safe to travel above, and sometimes well above the national speed limit if you know what you're doing. [...] If you choose to do it yourself, that's up to you, but always remember that basic safe stopping rule...
Always be able to stop on your own side of the road, in the distance you can see to be clear.
... and reasonably expect to remain clear.
That's like a breath of fresh air. A pleasure to read - Thanks!
WilliBetz
I'm sort of the wrong end of the country, although I have some wonderful recordings of a TVP trainer giving my car absolute death at Millbrook. He came back complaining that the brakes weren't working that well until I pointed out that he wasn't going to be able to pull 1g of deceleration down a 21% slope...
willibetz said:
R_U_LOCAL said:
For example, if you use up 50% of your available tyre grip with braking, you've still got 50% of the grip left available for steering.
Reg, I find much to admire in your contributions and desire for simplicity. But StressedDave does have a point to make, based on sound reasoning and much experience, and it's worth considering. Forum discussions can decline into pedancy, but if you're going to present figures it's worthwhile checking them for sense.
It probably makes more sense if I put it like this...
Use up 100% of your available tyre grip for braking, i.e. lock the wheels, and you've got bugger all grip left with which to steer.
An oversimplification? Probably, especially considering the advances in anti-lock braking and anti-skid technologies, but when it comes to practical, on-road instruction, I prefer simple, quick-to-grasp concepts which a student can understand without having a degree in physics.
That's not to say that Dave's point isn't interesting.
It's just not as easy for us mere mathematical mortals to get our heads round.
Actually your 'model' (for want of a better term) of tyre grip and my model agree exactly at the 100% usage points, i.e. when you're using all of your grip in one particular direction there is none available for anything else. Away from those points your model is unduly pessimistic compared to reality. That's not necessarily a bad thing to be, especially when you're dealing with people for whom the driving function tends to be a tool rather than a pleasure, and you have a limited amount of time to get techniques in place.
The pic above is a plot of available grip for a single tyre. Your model is the green diamond shape, reality is the circular bit.
However, in my experience, there's a couple of points to remember:
1. Nobody is particularly good at measuring acceleration, although we're generally good at measuring its rate of change. There are very few people who can tell the difference between 0.7g and 0.8g - that's why fighter aircraft have g-meters in the head-up display
2. Most of the really great drivers (road or track) work in the gap between your model and reality. Think about how much of the grip budget you use on entry (or more commonly) exit of a bend.
The pic above is a plot of available grip for a single tyre. Your model is the green diamond shape, reality is the circular bit.
However, in my experience, there's a couple of points to remember:
1. Nobody is particularly good at measuring acceleration, although we're generally good at measuring its rate of change. There are very few people who can tell the difference between 0.7g and 0.8g - that's why fighter aircraft have g-meters in the head-up display
2. Most of the really great drivers (road or track) work in the gap between your model and reality. Think about how much of the grip budget you use on entry (or more commonly) exit of a bend.
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