Shamelessly stolen from another forum, but I thought it raised an interesting question for people to mull over

Enjoy!

--8<---

I was in a meeting today when I was asked a question on cornering, I thought some of you might like a little teaser of a question which might just get the old grey matter working, some of you might know the answer immediately, in which case let the others fight amongst themselves.

You are out on the bike or in the car driving or riding along a lovely section of road for the very first time.

You are riding/driving in a national speed limit (60). You approach a bend which you have never ridden/driven before. The road surface is good, the weather is fine and clear and traffic flow is light. You decide to take the bend at 30 MPH. You come out the other side safely and realise that you could have gone quicker, so being a lovely section of road, you turn around and go back and ride/drive it again. This time you ride/drive the same bend at 40. It is still safe and legal and it still feels comfortable, so you do it again at 50 and again at 60.

On each and every occasion you have ridden/driven the bend it has been comfortable, safe and legal, but what is the correct speed for the bend? 30? 40? 50? or 60?

Not a trick question I assure you, answers on a postcard, and I refer to both car and bike as the answer is the same.

It doesn't say how far round the bend you can see - that would affect the "safe" speed as you need to be able to stop ok should the need arise.

If you can see that the road is clear all the way round the bend and the radius is such that it can be driven safely at the speed limit then that's what I'd be aiming to do.

^ what he said!

^ what he said!

Well , to be honest if it was that nice a bend and I was on my bike I'd possible be going a fair bit faster than the limit , but that's wandering off topic into the cat and fiddle thread....

What do you mean by "correct"

Correct from an "expecting the worst" point of view - 30mph

Correct from a "making progress within the limits of the car" point of view - 60mph

Correct from an anywhere in the middle point of view - anywhere in the middle.

I guess from a roadcraft point of view you need to be able to stop in the distance you can see to be clear (or half the distance - depending on how cautious you are ) so the distance you should be travelling around the corner would vary depending on grip levels, and how quickly your particular vehicle can stop in a controlled manner.

For a supercar you could probably go around it safely at 60.

For a mk1 fiesta or something it would be much slower.

If the road is an NSL then the correct speed is 60, however depending on conditions/driver experience it may be advisable to go at a lower speed say 30/40.

As pretty much all the others, it depends on where the vanishing point is, not "how fast can the car go?"

I know of several cases around here where the limit of grip for my Octy is "above the speed limit, even in the wet", but the vanishing point constrains the "correct speed" to 40 in the dry, dropping to half that in snow. I established the limit of grip by following a "right ba'heid" and just worrying about staying a stopping distance behind him.

30mph is the correct speed if the driver doesnt know the road , he has to anticipate what hazards may be around the corner out of view and to barrel around at a high speed based on the performance of his car would be adding to the risk that the corner already may provide

It's better to get a corner "wrong" by going around more slowly than possible than it is to run yourself off the road as you hadnt taken into account a hazard out of view

30mph.

The speed at which the tyres start squealing.

Some interesting and thoughtful responses as expected Also interesting to see that no-one picked 50mph, but the responses to the other three speeds were fairly evenly spread.

The published answer to the question is 30mph, based on the fact that solely with the information available on the approach to the bend, running through the System, 30mph was the speed that matched the limit point and so was the distance you needed to stop in should something develop as the limit point starts to move. So the assumption is that he got it right the first time and subsequent attempts were reliant on the car's bike's ability and information he'd gained beyond the limit of vision on previous runs which have potential to land you in problems.

However, I think stating that at all four speeds, were "comfortable, safe and legal" detracts from that message and suggests that if that was the case, the bend had been significantly misread 3 times and by some margin!

Chris

Some interesting and thoughtful responses as expected Also interesting to see that no-one picked 50mph, but the responses to the other three speeds were fairly evenly spread.

The published answer to the question is 30mph, based on the fact that solely with the information available on the approach to the bend, running through the System, 30mph was the speed that matched the limit point and so was the distance you needed to stop in should something develop as the limit point starts to move.

Except nowhere in the wording of the question is this mentioned at all.

The "correct" answer is based on information that you haven't been given and the whole question is completely invalidated.

As I said in my reply , the answer depends on the distance you can see around the corner which we don't know.

An interesting debate Chris - maybe that taster day would be a good investment of my time!

As others have said i feel "correct" is subjective

were you dirving your gran to the shops - maybe 15 would be correct

Surely the concern shoud be going back over a corner multiple times getting faster and faster. What happens when you finally go too fast and end up in the hedge/on-coming traffic/someone else's boot?!

I find that my "spirited driving" both on road and on track is "correct" if it's at a level i feel comfortable with, regardless of speed.

I've had to reign myself in when i've glanced at the speedo and been pushing on into 3 figures, but i've also had one of incidents at 20mph that makes you do the rest of the journey at 15mph, while contemplating all the what ifs

As I said in my reply , the answer depends on the distance you can see around the corner which we don't know.

Absolutely - part of the reason I offered it up for discussion to see what people were thinking and whether it became a guess-fest or people were questioning it

Chris

Edited 19 August, 200916 yr by ScoobyChris

Agree with those who question the question.

30 mph can be a well-chosen speed (or even too high) when going through a bend so sharp that you cannot see what's in front of you, e.g. where you could be surprised by animals (cattle, horses, sheep, deer),a broken down lorry or a harvester. But you don't find that kind of bends on a 60 mph road (not here in Sweden at least) and if there should be the odd example there would be HUGE warning signs, maybe even reduced speed limit through the bend.

Some interesting and thoughtful responses as expected Also interesting to see that no-one picked 50mph, but the responses to the other three speeds were fairly evenly spread.

The published answer to the question is 30mph, based on the fact that solely with the information available on the approach to the bend, running through the System, 30mph was the speed that matched the limit point and so was the distance you needed to stop in should something develop as the limit point starts to move. So the assumption is that he got it right the first time and subsequent attempts were reliant on the car's bike's ability and information he'd gained beyond the limit of vision on previous runs which have potential to land you in problems.

However, I think stating that at all four speeds, were "comfortable, safe and legal" detracts from that message and suggests that if that was the case, the bend had been significantly misread 3 times and by some margin!

Chris

Now, I'd have said 60mph, with the proviso that you should be able to see far enough to avoid a problem.

Agree with swedishskoda. The question is non-sensical as it asked out of context, with too little information given to make a valid decision. Paranoia is healthy on the roads but a good driver should be able to maintain the speed limit around all bends on the road, if it is not safe to do so I would say it is the fault of the relevant road authority for not flagging the corner with suitable warnings.

An interesting debate Chris - maybe that taster day would be a good investment of my time!

I hope so!

Surely the concern shoud be going back over a corner multiple times getting faster and faster. What happens when you finally go too fast and end up in the hedge/on-coming traffic/someone else's boot?!

In road driving, a *safe* speed is defined as one when you can stop in the distance you can see to be clear, and reasonably expect to remain clear. So, in good conditions, the speed around any corner is dictated by vision and to a lesser extent grip. After all, if you have that good a view through a corner, straightening it would lessen the grip required for a given speed.

The key thing is that the more you drive a corner, the more you build up local knowledge of that corner and with that comes the danger of that infamous phrase that I'm sure we've all heard people say "it's ok, I know the road". So the blind bend that you can always take at 60mph always gets taken at 60mph and 99/100 you get away with it. However, the 1/100 time just beyond the limit of vision there is a horse with a rider. Let's hope there's no oncoming cars and you can brake and swerve out of danger - but if there isn't, the results don't bear thinking about.

I find that my "spirited driving" both on road and on track is "correct" if it's at a level i feel comfortable with, regardless of speed.

I've had to reign myself in when i've glanced at the speedo and been pushing on into 3 figures, but i've also had one of incidents at 20mph that makes you do the rest of the journey at 15mph, while contemplating all the what ifs

This is a general "you" rather than directed at you, but I've emboldened part of that first sentence. One of the main things about advanced driving is to get you driving at a level which is *safe* and safety is measured by being able to come to a stop in the distance you can see is clear which might mean a safe speed in 5mph, it might be 155mph. Whether that ties in with feeling comfortable is down to perception of danger, which may be reduced if "you know the road". There's that phrase again Key is reading the road and taking in all the information available to manage the risk - no road is ever the same twice

Sorry for the rambling - I'll go and do some proper work now

Chris

Paranoia is healthy on the roads but a good driver should be able to maintain the speed limit around all bends on the road

Is it possible to expand on that point a bit?

Chris

is it possible to expand on that point a bit?

chris

:+1:

Agree with swedishskoda..

Thanks

...a good driver should be able to maintain the speed limit around all bends on the road, if it is not safe to do so I would say it is the fault of the relevant road authority for not flagging the corner with suitable warnings.

Now that would be stretching it a bit too far. The basic speed limit in Sweden is 70 km/h (~45 mph) and I know lots of country roads where going throug bends in 30 mph is foolhardy to put it mildly and 45 would be madness. But on a 60 mph road, as stated in the questions, such bends are not found.

And even if one expects warning signs one can never excuse oneself with their absence. It's like the lorry drivers stuck under viaducts saying "It wasn't on the gps". Use your eyes and thinking ability first!

Agree with swedishskoda. The question is non-sensical as it asked out of context, with too little information given to make a valid decision. Paranoia is healthy on the roads but a good driver should be able to maintain the speed limit around all bends on the road, if it is not safe to do so I would say it is the fault of the relevant road authority for not flagging the corner with suitable warnings.

So highway authorities should engineer roads that can be driven at the speed limit regardless of conditions? Why not lets all have robot cars that drive themselves with no human input?

Personally I prefer the intelligent driver option.

So highway authorities should engineer roads that can be driven at the speed limit regardless of conditions? Why not lets all have robot cars that drive themselves with no human input?.

Now don't be too hard, gocfella actually agreed with me As I said, the line of reasoning doesn't hold for all roads, but if the authorities decide to put the 60 mph limit on a road with sharp bends and no sight they did an awfully bad job. Surely there's some kind of regulations as to what's required of a road for having the 60 mph limit?

Of course, in the absence of solid white lines, you should maybe be considering driving at a speed that allows you to stop in HALF the distance you can see in case you meet a lapsed MIAM coming the other way, apexing the bend!

Of course, in the absence of solid white lines, you should maybe be considering driving at a speed that allows you to stop in HALF the distance you can see in case you meet a lapsed MIAM coming the other way, apexing the bend!

MAIM, surely?