Cornering basics 2 Assessing a bend without the limit point

[R_U_LOCAL]

There was considerable debate following my last post as to where the road went next. Debate no more, for all is revealed - a short straight, followed by a right hander...



Now, let's consider this next bend - as with the last one, it'd be fairly easy to assess using the limit point - I've got the hand of God to point it out again...



In this case, however, if you extend your observations a little bit - "look outside the box" a little, you'll pick up enough clues to allow you to assess this bend properly without having to use the limit point at all. The next picture is the same as above, but with the essential area circled...



In the circle, you'll see the road continuing uphill to the right, and you can also see a car travelling towards us. This shows you, almost immediately, the angle of the upcoming corner. It allows you to plan your position on approach, to get your speed and gear correct for the corner, and to plan the line you'll take as you drive around it. Let's move a bit closer to the bend...



Now, we're getting to a point where you'll be getting your speed and gear correct for the bend, and planning your line through it. Two potential hazards have come into view though - can you see them?...



There is an entrance to the left, right on the corner itself, which has a very limited view into it, and further up the road, there is a line of fencing which indicates a possible road off to the right. The presence of this road is confirmed by the small white car which is driving along it, towards our road.

Let's consider the entrance on the left first. Even without that entrance, if there are no on-coming vehicles, my plan would be to go offside through this corner - it gives you the benefit of making the radius of the turn as large as possible, so your car will remain as stable as possible through the corner. Another advantage of going offside through the corner is that this road appears to have been built with crown camber (raised in the middle and lower towards the edges to aid drainage). Now, crown camber can be a disadvantage when negotiating right-hand bends, as the slope to the nearside can destabilise a car, forcing it out towards the nearside. If you take an offside position, however, the crown camber actually helps you through the bend, keeping the car more stable.

There would be a third major advantage from taking an offside position through this bend. Remembering that we should always keep a zone of relative safety around us when we're driving, a move offside would keep you away from the entrance, and away from any vehicles which could potentially emerge.

Clearly, the plan would be different with on-coming vehicles present, and in that case, you'd have to lose more speed for the corner to allow you to remain safely on the nearside of the road, albeit towards the centre-line, away from the entrance on the left.

As for the junction to the right further up the road - it shouldn't alter our plan for this corner - if the white car emerged and turned left towards us, it wouldn't be anywhere near the bend when we negotiate it, but it could have some implications. Approaching it after the bend, you should be wary of other vehicles emerging or turning into th junction, and you could end up coming up behind the white car if it's turned right, so an overtake might now form part of your future plans.

As far as this single corner goes, however, it's not really too relevant, but it does show the benefit of an extended view.

As we get to the bend itself, it all becomes clear and the plan should fit into place nicely...



The muddy tyre marks coming out of the entrance on the left confirm that it's used regularly, so we're absolutely correct to move away from it. In the distance, you can just make out the white car which has turned left towards us, so we've got a nice clear run through the bend, and plenty of time to return to the nearside, from where we'll consider the next hazard...

[R_U_LOCAL]

Vaux said:

Is it not possible that there could be a hazard, hidden from view by the trees, between the indicated limit point and the area of extended view?
Not moving, but maybe a fallen tree, parked car?
Maybe I just can't see clearly enough.
Wouldn't planning to offside in this case bring you into a possible conflict?

Things like that are always possible - our plans should be based on what we can see and what we can't see, so yes, you're right. Have a look at the last picture though...




This is taken from a point which is still before the driver would turn in to the corner, and there's nothing to stop us going offside there, is there? If there were something which had been hidden which prevented us from going offside, then we'd revert back to the start of the system again - information has changed, so we'd reconsider our position, speed and gear before committing to the bend. Don't forget the safe stopping rule that we should always be applying too - always be able to stop in the distance you can see to be clear.

So, the answer to your question is - yes, those things, and a thousand other things could be hidden from your view on the way towards that corner. The trick is to include those possibilities in your plan, and always have an alternative plan.

[R_U_LOCAL]

7db said:

Think you could see a snake on a roller-skate in that last photo.

RoSPA won't teach it, nor will it dock marks for doing it. They are covering their arses.

I teach it, and so do the majority of Police driving schools. It's the correct course of action in that particular corner for all the reasons I listed in the original post...

Maximising the radius of the turn

Taking advantage of the crown camber

Moving you away from the nearside entrance.

I really can't see a downside to going offside. The hazard lines are only that - hazard lines - they indicate the presense of a hazard, but there's no requirement whatsoever to stay on the nearside of them as there would be, for isntance, with double-white lines.

And Willi - although my primary plan would be to go offside, as there is a good (but not perfect) view of the road beyond the corner, there would always be a secondary plan to remain nearside if something did come into view. I wasn't suggesting that you should commit to going offside - just that it would be the best option.

[R_U_LOCAL]

flemke said:

No disagreement with any of the above.
This is a pretty interesting bend, however.
The interplay of the adverse camber on the nearside and the fairly blind junction on the left suggests to me that one would want to approach the bend from hard on the nearside to get the view ahead and fatten the radius, hope to cut the corner but be prepared for something unsighted behind the cluster of offside trees, and seek to cut the corner in order to allow more space away from that blind junction.
That would lead to a bigger lift off the throttle prior to the bend than would otherwise be the case, wouldn't it?

If the bend were completely visible, i.e. there were no trees or hedge to the offside, then I'd be happy to approach this bend towards the nearside, take a line which cuts towards the offside kerb and then back to the nearside on the exit, and continue accelerating throughout.

As this isn't the case, and the view, although good, isn't perfect, then yes, I'd be holding a nearside position until I were closer to the bend and the view was better. As you can see from the later picture, the view does open up nicely, but as we've held the nearside position a little longer to confirm the view, then my position wouldn't be completely offside through the bend - it'd more than likely be straddling the centre line.

As you've identified, it'd probably entail holding back on the acceleration until that view opens up too, but acceleration sense is a very important skill in road driving, and adjusting your speed for corners just by using the throttle is a difficult and delicate skill.

Cornering on the road is a very broad-ranging subject, and I'll cover other aspects of it in future posts. I'll be looking at position on approach and lines through corners, linking corners, balancing the car on the throttle, and I'm also hoping to post a couple of videos once I've sussed out a way of mounting my camera in the car (one which doesn't entail Local Junior getting travel sick, anyway).

[R_U_LOCAL]

flemke said:

R_U_LOCAL said:

acceleration sense is a very important skill in road driving, and adjusting your speed for corners just by using the throttle is a difficult and delicate skill.

My instructor used to say (when I was on speaking terms with him) that, as a rule, you should accelerate in the first 1/3 of the typical straight and then lift in order to arrive at the next bend at the right speed to avoid the need to brake.
At first I thought that he was being much too conservative, but over time I have come to appreciate that that guideline is a pretty good one.

You're not on speaking terms with your instructor? That should make for some interesting lessons!

I've heard this 1/3 acceleration theory before, and although I haven't actually been taught it, I have tried it out and it does work on certain roads, but the bends have to be similar and consistent (i.e. not opening / tightening). I've no objection to accelerating further down a straight and getting entry speed correct with the brakes, as long as the braking is smooth and done with enough time to get a gear for the bend if necessary, before turning in and accelerating. Having said that, on the right road, getting your speed correct for corners just by lifting or pressing the accelerator is a lovely smooth way to progress if you're in the mood for loping along, rather than really pressing on.

rich 36 said:

Right about the time I see that fence,

[pic]picture of road[/pic]

Im thinking Horses (especially)

using the road and maybee heading towards the Elbow of the road & ME,

And the last place I want to have to slow and avoid them on the O/S verge
would be, (as I think you are saying)
....On the wrong side of the carriageway,
where I would now look slightly stupid as a failed boy racer

But lets discuss

There's no right or wrong side of the road - just the nearside and offside. You pay for all of the road, so why just use half of it?

I can see where you're coming from, but you're basing your assumption on a single static photograph. In reality, in a moving car, the view alters and improves on the way into the bend, and any horses would be visible long before you decided whether or not to go offside. As I've said before, you should base your plans on what you can see and what you can't see, and on any rural roads, accompanied horses and ponies are a possibility. That's why, as I mentioned before, you should always have a secondary plan, which, in this case, would be to lose more speed on the way in to the corner, turn in later, and remain to the left of the centre-lines.

[R_U_LOCAL]

rich 36 said:

'Accompanied horses and ponies are a possibility. That's why, as I mentioned before, you should always have a secondary plan, which, in this case, would be to lose more speed on the way in to the corner, turn in later, and remain to the left of the centre-lines.'

I'm not an overly defencive driver, but I'm very aware of the outcome
of people with less observation, pointlessly speeding in a rural area,
where as your pictures illustrate, numerous variables.


A bend
A fence
An opening, with the sun streaming through it
A path. on the side nearest that fence,

Further,
I would offer that beside the road bearing off out of sight
untill well through that bend, It appears to raise
as it reaches that paddock fencing as well,
which in my case makes me think,
'am I seeing the road climb beyond the hazard, or the hedge line?


I'm all for roadcraft but I would rather see the onus on caution
rather than misplaced optimism given this particular instance.

It's great to be cautious, but where do you draw the line? Yes, there could be horses around the corner, and your plan should take that into account, but what else could be there? And which of those possibilities should we include in our plan?

There could be a herd of sheep in the road, or a pheasant, or a cyclist who's fallen off, or a Japanese sniper, or a French couple making love, or an escaped lunatic, or a downed WWII Spitfire.

If you start considering too many "what ifs", then you'd never get above 20 MPH, and as my area of expertise is in performance road driving, then that's what my posts will be angled towards.

I'm not going to criticise you for driving with more caution than I do, but there are plenty of drivers out there who do enjoy driving at speed on country roads, and planning for an offside position through this particular road certainly isn't "misplaced optimism".

[R_U_LOCAL]

7db said:

Reg, Right-handers are something I'm working on. Where would your throttle be throughout this corner?

The throttle would be pinned to the floor from the point where I passed the NSL signs in the previous post - death before deceleration!

In reality, once I was happy that my speed and gear were correct for the bend, I'd apply the throttle just as I started turning the wheel. A little at first, to settle the car into the bend, and then increasing the pressure until I was accelerating quite firmly out of the bend, onto the next straight.

rich 36 said:

Point taken I'm sure,
although I think a Sptfire downed in the road a bit unlikely,

You're right - there's not that many Spitfires left these days. I notice you didn't argue about the Japanese sniper or the French couple though. Must be some interesting roads where you live!

[R_U_LOCAL]

7db said:

R_U_LOCAL said:

In reality, once I was happy that my speed and gear were correct for the bend, I'd apply the throttle just as I started turning the wheel. A little at first, to settle the car into the bend, and then increasing the pressure until I was accelerating quite firmly out of the bend, onto the next straight.

Does that mean a no-to-neutral throttle at turn-in and steadily rising to full as the lock comes off?

The initial turn of the wheel should be accompanied with a squeeze on the throttle. Imagine the steering wheel and accelerator are linked, so that turning the wheel applies pressure to the throttle.

[R_U_LOCAL]

willibetz said:

That's clear (and although 7db did tee himself up for a flippant response, he also deserved a proper answer) but I'd be interested in exploring this a bit more with you...

You will often (though not in the corner you've illustrated) make an initial turn of the wheel before the limit point starts to run / recede. This could be argued to be the most "risky" part of the corner...

- per Roadcraft, speed and gear are set but the available stopping distance (defined by the limit point) is still diminishing
- while the limit point is still advancing, the bend may still sharpen (cf. driving in Luxemburg)
- having turned the steering wheel you have reduced your ability to stop the car (cf. driving an Alfa 75)
- having picked up the drive, weight transfer will further reduce your ability to stop (cf. driving an old 911)

In such cases, I'm an exponent and advocate of trail braking until the limit point starts to run. My intent is to use the technique as part of a planned approach and as an aid to safety, rather than as a band aid to cover up for poor bend assessment.

I'd be interested in your thoughts...

WilliBetz

You're making the mistake that many people make in thinking about cornering, and you're getting track thoughts and techniques mixed up with a road driving mentality.

On the road, there are so many variables, that, although spirited driving is fine, you should rarely be approaching the cars limits. If you're using the limit point to assess the bend, you'll be bringing your speed down so that it matches what the limit point is doing - as you get closer and closer to the limit point, your speed should continue to drop until you're happy that you've assessed the tightness of the bend correctly.

However, you don't just use the limit point on the approach to the corner - it should be continually reassessed because, as you've pointed out, corners can tighten up. The Roadcraft system (if that's your chosen method) copes nicely with this by stating that if information changes (i.e. the limit point shows that the corner is tightening), then you can revert back to the start and readjust your position/speed/gear if necessary. You can't be absolutely sure about a blind corner until it starts straightening up, so you should always have this option in reserve. That means that, on corners in which the only way to assess, due to a poor view, is with the limit point, then you should always have a little in reserve. If you keep that bit in reserve, then the fact that your braking capabilities have been reduced when you turn the wheel won't be as important - you should still have enough tyre grip left to stop the car if you need to.

That's not to say you shouldn't be on the gas as you enter the corner - you only need to squeeze the throttle enough to maintain your chosen speed into the corner and keep the car nicely balanced. As you move round the bend, your continual reassessment of the limit point and any other information will let you know when it's opening up, and therefore when you can start pressing the accelerator more firmly.

Trail braking is a good track technique, but not for the reason you've mentioned - keeping the brakes on past the point of turn-in creates extra front-end grip just when it's needed, but again, that's a technique best suited to the track, which allows a driver to take a little extra speed into a corner, settle the car through the corner, and then, hopefully, carry a few extra MPH onto the next straight. These are the priorities of a track driver though, and not a road driver.

Staying on the brakes into a corner until you're sure of how tight a bend is has a couple of problems.

Firstly, it will often mean that you're then taking a lower gear to suit your speed, whilst you're still turning the wheel. This isn't ideal - I always like to have speed and gear completely sorted out before entering a corner to maintain maximum balance through the corner.

Which is where the second problem comes in. If you're travelling along at a constant speed in a straight line, and you turn the wheel, the forces acting on the car and the additional lateral grip will slow the car slightly. To keep optimum balance in a car whilst cornering, you should apply at least enough throttle to maintain your speed and counteract that natural tendency for the car to scrub speed off. If you keep the brakes on whilst entering a corner, you're doing the opposite, and demanding more from the available tyre grip at the front, whilst keeping weight away from the rear which, in the old 911 that you used as an example, is often where it's most needed.

[R_U_LOCAL]

*Gets headache*

*Goes for a lie down*

[R_U_LOCAL]

Unfortunately, as I've said before, baffling people with science isn't the best way to put basic principles across. You've picked some points to argue with which we actually agree on - take this one for example...

StressedDave said:

RUL said:

That's not to say you shouldn't be on the gas as you enter the corner - you only need to squeeze the throttle enough to maintain your chosen speed into the corner and keep the car nicely balanced. As you move round the bend, your continual reassessment of the limit point and any other information will let you know when it's opening up, and therefore when you can start pressing the accelerator more firmly.

Actually that depends on the car - in the MX-5 it's around 20% throttle; in the Ford Ka it's 80-90% and both values depend on the cornering acceleration.

Of course it depends on the car, as it depends on countless other variables, but being specific about how much throttle in which cars would take up all the sites bandwidth - which is why I simply said "enough" throttle - surely people can work out what I mean from that? No-one expects to be told exactly how much throttle to apply, and without advanced electronic displays, I'd struggle to tell the difference between 20% throttle and 40% throttle.

I have to take issue with this though...

StressedDave said:

I did a race engineering course a couple of years back, and one thing that stuck in my mind was the comment "80% of your lap time comes from the first 5 metres of a corner". It's as valid on the road as it is on track

I don't see the relevence at all. Lap times and entry speeds have no relevence on the roads whatsoever.

[R_U_LOCAL]

Philbes said:

Earlier in this thread a number of people agreed on moving to the offside ('wrong' side of road) when taking this bend. Of those of you who agree you would this, would you still do so if you were being folowed by a police car? Not necessarily closely followed, but near enough to observe you take the bend on the 'wrong' side of the road. If the presence of a police car would change you behaviour - why?
This is a test I often use to assess my driving - would I drive the same if a police car was following me?

Yes I would, but I suppose I'm in a priviliged position - I know what the Police have been taught, and I'd expect them to do the same. I'd also have some choice words for any Police Officer who stopped me for doing it.

A more relevent way for me to look at it is would I stop someone for driving like that? The answer is no.

[R_U_LOCAL]

willibetz said:

Reg, thanks for the comprehensive and thoughtful response. I'm not entirely sure I agree with all of your comments, so perhaps we can explore them a bit more...

Ok Willi - I'll answer your points as best I can. Apologies in advance for using the quote system to produce such a long post, but it's the easiest way for me to answer without missing anything.

willibetz said:

R_U_LOCAL said:

You're making the mistake that many people make in thinking about cornering, and you're getting track thoughts and techniques mixed up with a road driving mentality.

Maybe... But, while I enjoy both, I am sufficiently conceited to think I'm pretty clear on the applicability of techniques.

That's fine for you, and I'm not trying to take anything away from your ability, but I'm conscious that there are many people who read these threads, with a wide range of ability and experience. If I hammer home the message about not confusing track and road techniques, it's not really personally directed at you - it's more of a general "be careful" message to the general readership.

willibetz said:

R_U_LOCAL said:

... If you're using the limit point to assess the bend, you'll be bringing your speed down so that it matches what the limit point is doing - as you get closer and closer to the limit point, your speed should continue to drop until you're happy that you've assessed the tightness of the bend correctly.

Agreed. Though, as we both accept, there are situations when you will enter a curve before it is possible to assess the tightness of the bend accurately. It's in that circumstance that I would consider trail braking. For the avoidance of doubt, in this context, I'm talking about planning your braking so that you are still tapering off the brake while beginning to turn into the corner. I'm definitely not suggesting that it's appropriate to try and maximise the use of available grip on the way into an unsighted corner on a public road. The benefit is that you can stop the car more quickly and less dramatically should the need arise, in the early portion of a bend before the limit point starts to run and you can safely pick up the throttle.

Right, I'm with you. I don't see anything wrong with your approach if it suits you - it obviously wouldn't score you any points with advanced driving examiners, but that's certainly not what my posts on here are all about. If you find a technique that suits you, then I'd say carry on with it - What I would say is that, rather than continuing to have the brakes applied whilst entering a bend that you're not 100% sure of, my preferred method would be to lose a little extra speed to compensate before the bend, rather than staying on the brakes, but I understand your technique.

I don't think I'll be taking it on myself though.

willibetz said:

R_U_LOCAL said:

However, you don't just use the limit point on the approach to the corner - it should be continually reassessed because, as you've pointed out, corners can tighten up. The Roadcraft system (if that's your chosen method) copes nicely with this by stating that if information changes (i.e. the limit point shows that the corner is tightening), then you can revert back to the start and readjust your position/speed/gear if necessary. You can't be absolutely sure about a blind corner until it starts straightening up, so you should always have this option in reserve.

So you take an educated guess at speed and gear before turning the wheel and picking up the throttle, but reserve the right to start the procedure again if information changes? I've certainly seen systematic drivers employ this technique, and I don't argue that it can be a safe approach if you have adequate grip in reserve - I cited Luxemburg, in my last reply, as the best example I can recall of a country where the road planners specialise in designing contracting radius curves on the approach to hairpins. However, I would contend that your preferred method, in the context of progressive road driving, is:

- a distortion of RoadCraft... (sorry about that!) It's not really that the information changes when the bend tightens. The bend was the same shape yesterday, and it'll be the same shape tomorrow. It's not analogous to the Spitfire landing in front of you. It's more that you decided your plan before adequate information was available. Which would be a fault if we were discussing it in the context of the approach to a roundabout.

- horribly inelegant, because your best guess plan will occasionally be wrong and need to be started over

- less progressive, because you need lots of grip in reserve to cater for those sneaky Luxemburger road planners

- less safe, because it takes longer to stop a car from an initial state of acceleration than from an initial state of deceleration.

No, it's not a "best guess" - it's an accurate assessment of the bend, based on the information - all the information - available to the driver at that time. The fact that the information can change as you enter/negotiate the bend is just a fact of life. If you're moving forwards, the information changes all the time. Even in the most seemingly constant-radius bends, you should constantly reassess the corner, just in case it throws up any surprises, but it's not guesswork.

There are times when you can get it wrong, of course, but going back to system can correct these errors. You're right - it's not elegant, but it works, and on the odd occasion where the information does change, compared with your initial assessment, then it'll sort the problem out.

willibetz said:

R_U_LOCAL said:

Staying on the brakes into a corner until you're sure of how tight a bend is has a couple of problems.

Firstly, it will often mean that you're then taking a lower gear to suit your speed, whilst you're still turning the wheel. This isn't ideal - I always like to have speed and gear completely sorted out before entering a corner to maintain maximum balance through the corner.

Interesting point. If a gearchange is necessary, I accept that you would need to employ another circuit technique - the heel and toe gearchange - or confine yourself to a car with an SMG gearbox

While I accept that you may not be allowed to train or drive using these methods in your club, I genuinely believe that this is an area where race driving techniques can be beneficially applied to road driving.

I'd be interested in your thoughts, and thanks again for the opportunity to discuss it.

WilliBetz

Not having a dig at my M3 are you Willi? I'll have you know it's an SMG1, so I still have to take a hand off the wheel to change gear!

Again, I see nothing fundamentally wrong with heel/toe gearchanges if you're comfortable with it and you can do it safely. I've never taught it, as the courses were never long enough, and the course curriculum never required it, but it's something I'll do myself, on occasion, if I'm having a bit of fun in the MX-5.

It's simpler, though, for less experienced or skillful drivers to start with sorting out speed and gear before the bend. If they then choose to move on from there to your methods, then fine.

[R_U_LOCAL]

StressedDave said:

You have to make it as simple as possible, but not too simple that you're overgeneralising. Just because you find it baffling, doesn;t mean that everyone else does. I know of at least one poster here who would feel shortchanged if I didn't use a little bit of science rather than the 'trust me I'm an instructor' method.

I can’t see anywhere where I’ve overgeneralised. Don’t get me wrong – I’m happy to accept criticism – I wouldn’t have started posting this stuff in a public forum if I wasn’t, but I really can’t see where I’ve overgeneralised anywhere. If you could point out where I have done, it’d be easier to answer the criticism.

Conversely, I do think you have a tendency to overcomplicate things, but at least I’ve specified exactly where, so you know which points I mean.

I'm not baffled by your posts either, but I'm sure a lot of other readers will be.

And I can’t remember anywhere where I’ve written “trust me, I’m an instructor”. Again, if you could point out where I’ve said that, it’ll be a great help.

StressedDave said:

Replace the term 'lap time' with the phrase 'ability to make progress', and you'll get the gist of what I meant. I wasn't talking about entry speeds or cornering close to the limit of adhesion.

If that’s the case, then you should be more careful to write exactly what you mean. As I’ve just mentioned in a recent post, there are a lot of people with very varied skills and experiences who read this forum, and I don’t want them getting mixed up between track skills and road skills. Some track skills are perfectly transferable, but others need a good grounding in basic road skills first.

Have a look back at the thread title – “Cornering basics”. I’m not really sure how I could have made that any clearer.

[R_U_LOCAL]

Don't get me wrong Dave - I love a good debate, and I didn't feel disrespected. We all have something to add to the discussion, and I'm happy to admit if I'm wrong about something. I just like people to be a bit more specific, that's all.

I just think it's a subject which benefits from simplifying rather than complicating. I like to show people that there's no real "black art" to advanced driving, and that these are skills that can be learned by anybody. It is interesting to look more scientifically at what's happening to a car under different situations, but sometimes, you've got literelly a few seconds to take in information, process it, formulate a plan, together with one or more contingency plans, whilst also looking ahead to the next hazard and the one after that.

In those situations, the simpler the explanation, the better, as long as that simplification doesn't go too far and leave the driver in doubt about what to do.

Plese don't stop challenging me - it keeps me on my toes.

[R_U_LOCAL]

That's an interesting video Dave - makes my amateurish efforts look a liitle poor by comparison.

I'm in the process of devising a camera mount for my car so you can compare techniques, but I'm afraid you'll have to listen to the engine to see when I'm applying the throttle.

I can't say it'd be any different than in your video though.