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Astraist
Master Driver



Joined: Mar 27, 2010
Posts: 209

PostPosted: Fri Jun 03, 2011 6:55 pm Reply with quote Back to top

A discussion on another board reminded me of a few ground rules for safe cornering. These rules apply to any turning, but they are especially important when driving in winding mountain roads (which I know are not as common in the US as they are in Europe). These roads can conceal surprises around the bend: A stalled car, an oncoming car that runs wide, something slippery on the pavement or a sudden "closure" where the radius becomes smaller and the bend tightens.

The ways to avoid surprises or slides around bends are various. It beings with the setup of the car: A proper driving position to achieve good control over the steering and pedals; using the left foot to brace your body against the dead pedal to the right; gripping and turning the wheel effectively, preferably in a technique I previously mentioned on this board; Maintaining the car's tires, tire pressures and dampers carefully.

The next point is to understand car dynamics. I already introduced those theories in the past. There are two important models. The first is the Friction Circle and the second is about transients and weight transfers. The friction circle dictates that each tire has 100% of overall grip. If you use 20% for braking, you only have 80% left for cornering. According to this model, it is best to keep the car on so called "balanced throttle" while turning so that the car is not slowing down or speeding up, and the tires' grip be used only for cornering, and this technique is also promoted by our respected board member GerardWon.

However, we must consider transient handling and weight transfers too. The car is not practically cornering steadily before we finished turning the wheel into the corner. From the first moment in which we begin to steer till just after we finish turning in, the car is said to be changing direction or "yawing" into the corner. The effectiveness of this transient is based purely on the two front wheels which turn the car into the corner.

Once turned, the car achieves a steady state of cornering, where the cornering force is now derived from the two wheels "outside" to the direction of the corner. Coming out of the turn, the rear wheels take the task of straightening the car. By applying this theory, we can understand that better results be yielded if we brake ever so lightly coming into the corner. By braking the car transfers weight to the front (nosedives) and increases the overall grip of the front tires.

Simultaneous to the point where we finished turning the wheel into the corner, we seamlessly move to the throttle pedal and keep the car on constant throttle, so the car is balanced over it's two outside wheels. From the point where we start straightening the wheel, we increase the throttle to accelerate slightly, where this acceleration makes the car "squat" over it's rear wheels, giving them extra grip for straightening the car.

Of course all inputs of throttle, brakes and steering have to be accurate and very smooth. Most drivers become more jerky when they try to drive faster, where in fact "real" drivers (Race drivers) are most smooth when they drive the limit of the car. With that being said, some drivers are all too smooth and not as quick or decisive as they should be. This is especially notable in sharp corners, where it's possible to turn the wheel quite rapidly without disturbing the balance of the car.

Vision also carries an important role. We need to look up and notice the corner in the greatest advance possible. We need to asses it's steepness and every detail we can learn about it. The most important tool in this respect is the Limit-Point. The limit point is the far edge of our visual field into the corner. It can be seen as an "arrowhead" which seems to unfold and get away from us as we get closer. We can use it to estimate more accurately just how slow the corner needs to be driven through, and whether it begins to tighten up later into the corner.

Our vision can also help us pick up other clues as to what might await past a "blind" bend: You can look at the skyline of the light-poles/telegraph poles/trees, etc; cars can be seen or heard as they come around the bend or brake into it or through it (might indicate a surprise up ahead) in night you can look at the light beams of an oncoming car to estimate the bend's tightens.

Vision is also used to dictate our cornering line. The line is supposed to help us take the corner more safely. In theory, it would be best to make the turn as "flat" as possible by staying on the far end of the lane, and than "dive" towards the inside of the bend and track back to the "high side" coming out. In real life driving, this line might not be as good around a long or tightening bend, and it does not give us a very good idea of what's around the corner.

So, the best option is to do the same, but turn into the corner later and "touch" the inside line much later coming into the corner. The point where we contact the turn's inside line is called the apex and on the road we should strive for one which is very very late, so we can have an earlier "peek" around the corner. In fast turns with an open visual field, you can take a line where your apex is perfectly mid corner.

The role of vision in taking the line is by looking as deep into the corner as possible, visualize the desired cornering line and setting an imaginary "turn-in" and "apex" points. Than it's a matter of shifting focus. Before turn-in, you shift focus to apex, before apex, you shift your focus to the limit point which will not begin to open up to the exit. Note: Looking ahead into the corner might mean looking aside, or even through the side window (and not the windshield).

Another point I want to stress regarding the cornering line is the compromise of the smoothness of turning in. Sometimes, as you negotiate a sharp, blind corner, you might choose to keep your turn-in point later and than turn-in a bit more rapidly. This is not a desired situation because it rocks the car slightly, but in corners where there is no other choice, it allows to take even a better of a peek around the corner. Use with caution.

Cornering lines are nicely covered (with sketches) in my Blog Post:
http://drivingnation.blogspot.com/2011/01/all-about-cornering-lines.html


The last point is about something called "hinting." Remember the turn-in point? Well, intuitively turn-in would mean that at that point you start turning the wheel into the corner, right? Wrong. At turn-in, you should have already began turning the wheel. The front wheels take about one quarter of a second to react to your initial steering input, and it actually takes a longer time when you brake coming into the corner (like I described above), so the solution is to begin to steer a fraction of a second "too early" and in one rhythm with the whole steering input. This means that at your actual turn in point you will receive an immediate response from the steering.

Another (last) note refers to successive corners. In an event of successive corners, try to engineer your line so you can "engineer" a little straight line in between the two. When you have to steer from side to side, do it without pauses in the middle, but in one smooth movement from side to side.

Co-ordinate the movements of the car's load in both the longitudinal and lateral directions: You turn into the first corner with the brakes still on. Once you finished turning the wheel into the corner, you apply "constant throttle" to keep the car at a constant speed and, as you steer from right to left, let go of the gas just when you are straight and reapply it after you finished turning in again.


The Ten Commandments of proper Cornering

1. Adjust the desired cornering speed in a straight line. Remember "Slow-in, Fast-out."

2. Enter the corner at a speed below your comfort level, well below the car's limits and matched to the visual field.

3. Steer accurately, smoothly and decisively (in that order). Try to steer with as least hand motions as possible. Be aware of the possibility that you might have to compromise turn-in smoothness for vision.

4. Do steer "too early." Comence steering a fraction of a second too early to achieve an immediate steering response in the moment of truth.

5. Use the car's mass to accelerate the transients in coming and out of the corner. You should decelerate into the corner (from straight to the point where you finished turning the wheel into the corner) and accelerate out of it (from where you start unwinding the steering to the point where it is fully straight.

6. Take the right line for vision, gap from other cars and grip (in that order). Strive for the earliest late apex possible.

8. Think of the "critical wheels." While cornering the car turns into a bike. It turns-in with it's two front wheels, achieves steady-state cornering over it's two outside wheels and straightens out over it's two rear wheels. Carefully distribute the car's weight over those wheels and place the two outside wheels on the grippiest possible stretch of tarmac.

9. Turn the wheel only once. Afterwards, steer by throttle. Maintain a constant amount of throttle which keeps the car at a constant speed. Increase throttle for an increasing radius and decrease throttle for a decreasing radius.

10. Look up: Visualize your desired line through the corner in advance and set imaginary "reference points" for turn-in and apex. When you are about to reach turn-in, shift focus to apex. Before apexing, shift focus to the limit point as it opens to the following straight. Use your vision to gather all possible clues as to what might be around the bend.
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GerardWon
Master Racer



Joined: May 10, 2011
Posts: 46
Location: NYC Area

PostPosted: Sun Jun 05, 2011 12:19 pm Reply with quote Back to top

Good post.

My wife's from N. Italy about 30 miles south of Switzerland. And yeah those mountain roads make the one's here in NYS leading up to Hunter mountain (as an example) look like a joke.

I drove up to her mom's home town, into the mountains just outside of Bobbio in Piacenza The expression 'I'd rather be lucky than good' comes to mind. Like one of the Unser's said about a section of road in the race at Pikes Peak 'If you go off (the road) it'll be a long time before you hit anything'.
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Werfelgartner
Member
Member



Joined: May 04, 2011
Posts: 20
Location: USA

PostPosted: Wed Jun 15, 2011 1:19 am Reply with quote Back to top

Its really nice and useful information. Thank you for sharing with us.
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Ardall
New member



Joined: Jun 17, 2011
Posts: 1

PostPosted: Fri Jun 17, 2011 7:26 am Reply with quote Back to top

In my 5 year driving experience once i faced an accident. Very Happy
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myownworld
Site Admin
Site Admin



Joined: Jan 06, 2010
Posts: 485

PostPosted: Fri Jun 17, 2011 7:51 am Reply with quote Back to top

Welcome to Fun And Safe Driving Ardall. Thank you for joining the forum.

And well done for making it safely on the roads so far! Smile

So, what would you say is your secret for staying safe and preventing accidents on the road?
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ellaboswell
Member
Member



Joined: Apr 29, 2011
Posts: 44
Location: USA

PostPosted: Sun Jun 19, 2011 11:35 pm Reply with quote Back to top

Good post with nice information. Thanks
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sgtrock21
Seasoned Driver



Joined: Jul 15, 2012
Posts: 120

PostPosted: Fri Jul 20, 2012 9:13 pm Reply with quote Back to top

Astraist, There are a few mountain roads in the US that will scare the Sh*t out of you. Ah yes. The decreasing radius turn. I think this is the best reason for not using excessive speed on an unfamiliar road. It can be a very nasty surprise!
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Misha
Site Owner



Joined: Aug 02, 2006
Posts: 704
Location: McLean, VA, USA

PostPosted: Mon Jul 30, 2012 8:14 pm Reply with quote Back to top

I would think the USA is not the worst about it. Did you drive in Turkey? Or Russia for this matter? I don't even touch on countries like Afghanistan or India LOL
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sgtrock21
Seasoned Driver



Joined: Jul 15, 2012
Posts: 120

PostPosted: Tue Jul 31, 2012 12:32 pm Reply with quote Back to top

Misha wrote:
I would think the USA is not the worst about it. Did you drive in Turkey? Or Russia for this matter? I don't even touch on countries like Afghanistan or India LOL


I have driven in USA, Canada, Mexico, Germany, Bosnia, Croatia, Hungary, Spain, and Portugal. After witnessing driving in Greece and Turkey I am glad I did not have to attempt driving there. Bosnia was the worst where Fiat 500 drivers try to physically intimidate 6000lb HUMVEEs!
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myownworld
Site Admin
Site Admin



Joined: Jan 06, 2010
Posts: 485

PostPosted: Tue Jul 31, 2012 12:37 pm Reply with quote Back to top

wow, you're been around the block a bit!

In the past, i've driven in south asia and paris - both hard in their own ways.

South asia because there is absolutely no concept of any rules, no to mention the wide variety of vehicles, including cows and donkeys!

Paris: tough because of the perpetual tourists!

And now I drive in london - which at the moment is a nightmare too!
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sgtrock21
Seasoned Driver



Joined: Jul 15, 2012
Posts: 120

PostPosted: Tue Jul 31, 2012 4:10 pm Reply with quote Back to top

myownworld wrote:
wow, you're been around the block a bit!

In the past, i've driven in south asia and paris - both hard in their own ways.

South asia because there is absolutely no concept of any rules, no to mention the wide variety of vehicles, including cows and donkeys!

Paris: tough because of the perpetual tourists!

And now I drive in london - which at the moment is a nightmare too!


In larger European cities I felt like I had driven around the same block a hundred times trying to find a place to park. I wanted to ask how London traffic was this week? I have been told it is "horror show" on normal days. I imagine it has now grown to "Olympic" (sorry for the pun) proportions.
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myownworld
Site Admin
Site Admin



Joined: Jan 06, 2010
Posts: 485

PostPosted: Wed Aug 01, 2012 1:48 pm Reply with quote Back to top

lol @ sgtrock. Yeah, I know... driving around some of those european cities can age you faster than you think!

As for the traffic in london, it's definitely grown to 'olympic' proportions (haha, good one that!) these days - but that's because of the special lanes they've opened just for the athletes and officials to speed past by, while the rest of us simmer, stuck in jams lasting for hours on end! Oh the joy.... Confused

To tell you the truth, most londoners have left town for a holiday abroad and escaped the mayhem altogether. I think all the hype for the games was so overdone that by the time the actual event started, people were already sick of it.

Oh you should hear everyone moan and complain....waiting for the 'circus' to leave asap!

But of course, the 'official' news is that we londoners are beaming ear to ear with pride and cannot contain our joy at being the hosts... Wink
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sgtrock21
Seasoned Driver



Joined: Jul 15, 2012
Posts: 120

PostPosted: Sun Aug 05, 2012 4:06 pm Reply with quote Back to top

Misha wrote:
I would think the USA is not the worst about it. Did you drive in Turkey? Or Russia for this matter? I don't even touch on countries like Afghanistan or India LOL


I just viewed your "Driving around slippery corner in Croatia" video. It appears to be water on ice. Yikes! In my experience that is the very worst. I had a minor accident under these conditions. All wheel drive and anti lock brakes were completely ineffective!. I have visited Rijeka twice. Our Blackhawk helicopters were delivered there by ship. I flew in and out and did not drive there. My driving in Croatia was limited to Trogir and Split. I did not experience any insanity at those locations. It was in May so there were no adverse weather conditions.
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sgtrock21
Seasoned Driver



Joined: Jul 15, 2012
Posts: 120

PostPosted: Sun Aug 05, 2012 4:43 pm Reply with quote Back to top

myownworld wrote:
wow, you're been around the block a bit!

In the past, i've driven in south asia and paris - both hard in their own ways.

South asia because there is absolutely no concept of any rules, no to mention the wide variety of vehicles, including cows and donkeys!

Paris: tough because of the perpetual tourists!

And now I drive in london - which at the moment is a nightmare too!
From what I have seen in travel videos and friends stories I don't think I could handle Asia. Animals used as transportation would be too much! I do know what you mean about total road anarchy. My experience in Athens was Taxi, Bus, and pedestrian (which I consider an endangered species there). The greatest danger for pedestrians were the scooters travelling 30 to 40mph on the sidewalks!!! I assume they have traffic laws but no one pays any attention to them.
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myownworld
Site Admin
Site Admin



Joined: Jan 06, 2010
Posts: 485

PostPosted: Thu Aug 09, 2012 9:28 am Reply with quote Back to top

lol @ sgtrock: Athens sounds no different than paris!

And scooters? oh yes, I forget what a hazard they can be.

Have I mentioned that in france they had a rule (apparently, an EU regulation) where on the motorways they have huge warning signs for an approaching speeding camera. Net result was that everyone waited for the warning board to come...slowed down till the camera came and then went rushing off at neck break speed again.

See, that below is just the warning for the camera itself:

Image


Last edited by myownworld on Thu Aug 09, 2012 11:36 am; edited 1 time in total
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