52 Limit Points
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- Опубліковано 8 лют 2020
- Limit points (sometimes referred to as vanishing points) can really help you to assess the tightness of a corner and make a good assessment as to whether your speed on approach, and through the corner is correct.
During the video, I refer to the following previous videos:
04 Cornering: • 04 Cornering
31 Emergency Braking: • 31 Emergency Braking
For more information about advanced & performance driving, visit my website www.reglocal.com - Авто та транспорт
"Could there be an injured child lying in the road just there?" is the question I usually ask myself. It's a bit grisly to contemplate, but it wakes me up quickly when I start to get sloppy.
As the comment below from Ian Barsby, I have recently started my IAM Advance Course and I am also really enjoying the lessons, No.4 tomorrow. I have looked at every one of your videos, certain ones, more than once and at 78 years old I had long forgotten how important it is to follow these modern lessons and forget how over the years driving (61 years), it's easy to get lazy. I look forward to becoming a better driver and receiving a certificate (I HOPE)! Back now to limit points. I wish you and all the other AIM students a happy New Year.
That video is essential viewing any driver the wants to make good progress safely on any road that has bends and undulations. Once again good observation is essential, reading the road ahead main beam to dip and mirrors. I love the drone footage at the end.
A great video, Reg! Thanks! I've recently started my IAM Roadsmart advanced driving course and am enjoying it. When the rain stops, I'll be out practicing what I've heard/seen here. Very clear information about limit points there Reg. Cheers!
Your videos are first class Reg!
The B6255 - Hawes to Settle in North Yorkshire. I have driven this road, both ways. It is a superb piece of road for this kind of drive. National Speed Limits and variable speed limits to keep you alert, with bends. You can see Ingleborough on left of screen @2-33. Also, a good view of the Ribbleshead Viaduct @3-44, with Whernside in the background. Interesting video, that is instructive and enjoyable to watch:
Your videos and your book have certainly improved my driving plus reading road craft as helped alot thank you reg ...😊
Great stuff as always, Reg! Surprised it took until video 52 to get one specifically on limit point analysis!
Another great video! Love your book too Reg.
Again, thanks for this Reg. I am currently in the North Sea until next week and am eager to put your advice into practice when I get home.
Customers asking how fast they can take the corner IS actually a very valid question if they want to know it. I get asked it all the time. The answer as you quite rightly say being the speed should be totally dictated by the available view but of course within the legal speed limit. Unfortunately you failed to mention other essential factors such as any creatures, for example that may suddenly appear and road surface/conditions which would affect the braking distance and handling ability.
Fantastic explanation...I'm an ADI and I've learnt so much more from your videos
Thank you
What a brilliant instructional video
Excellent explanation.
Just brilliant!I was struggling understanding the limit point. Thank you
Excellent help before my driving course!
Another great video! Loved the last one on off siding. Was taught off siding on my ambulance blue light course back in 94, but like you said it's not taught much these days. Wondering if you might consider making a video on making progress in built up areas? Ie using the lane of least resistance on 2 lane roads. Also what's your view's on lane merging? Do you advice merging lanes early like we in England like to do or driving up to the merge point?
Again thanks for the great videos.
This should be titled , chasing the limit point , as I remember !
Great video..Keep’m comming
Thank you Reg Local
WooHoo - 2 vids in one day!
That bloody sat nav is right in the way to see the limit point much of the time!
love the video... I'm trying to apply this, and finding it gets me looking much further ahead (not just at the limit point)... how about a video on crests and dead ground? How do I go about judging the speed? If I apply the limit point rules, I'd be taking a lot of speed off only to find that the road surface is only just out of view - but may be I should be more cautious! We have some spectacular examples on the A68 in Northumberland and I'm amazed how almost no-one brakes before the crest.
Reg.ur videos are very good.and clear explations. Thanks.
I seen ur conection in the bmw club journal. Iv sub to ur chanal.
Nice explanation of the limit point. The only thing I thought that should have been additionally mentioned is how nearside and offside hazards must also influence our speed, and not just 100% the limit point. I too dislike the "chasing the limit point" phrase.
I would love to see you applying limit points to unrestricted roads on the isle of man.
Torin Storkey Same laws of physics 😉
Its on the list Torin!
The limit point is still the limit point, on every road, even in the Isle of Man 😂😂
Excellent video, thanks. I very much like the emphasis at the start and finish of the video on being able to stop in the distance to the Limit point. You use the term static or stationary for the limit point in the middle part of the bend. I prefer to use the terms matched or constant. Although you explain what you mean by it I feel that calling the limit point static is potentially confusing. I find it useful to demonstrate this at low-speed asking the student to identify when the limit point is closing then matched then opening. I felt that the road you used was rather a quick one for demonstration of the use of limit points within the speed limit. I would like to see another video covering the use of Vertical Limit points over crests.
Really good explainer that Reg. Would you mind if I point som of my pupils toward your video ? I'm a PDI at the grand old age of 55
Hi Reg, I notice you don't in conjunction with limit points talk about "cornering lines" such as wide, tight wide and apex points, early actual and late.. Any particular reason why?
Many thanks for that. The bit I struggle with is commentary. On a simple bend, something like "Left hand bend ahead" . . . "Moving to the right to extend the view" . . ."limit closing" . . . "holding" . . . "and opening" ( or "and open" if it happens too quickly). Thats all well and good on a plain bend, but on one that tightens up half way round, or an interlinked series of bends its often hard to keep the commentary in line. My local group and examiner are quite rightly keen on limit point commentary demo. Of course you don't comment on what is obvious to the examiner/observer e.g. the gear changes. That said it was suggested in an auto if I use manual gears to say why (which is hard again to fit in). Perhaps scope for a specific video, if not already elsewhere? Many thanks. (I'm self isolating, and only in the car e.g. to go for medicals, so the videos are a massive help at the moment).
Lots of videos on my channel covering commentary, automatic gearboxes, observations & much more John. Have a look through this playlist: ua-cam.com/play/PLTpqGstmcT4mWQudiEenmhcFSDL9Vh17p.html
Everything else, including travel/driving videos & bikes stuff is here: ua-cam.com/channels/8fDyubAs3eLup-3COgsyRQ.html
Thanks for your interest!
The limit point when done right enables us to achieve the optimum speed for safety around a bend corner or curvature. However that is all it does. Just because we are following the limit point and remaining at the same distance away from it does not mean that we are actually driving or riding at a safe speed at all. Far from it we are in just as bad a danger even though we mistakenly feel safe doing what we are recommended to do in the Police Roadcraft Manuals and all training bodies.
If you read any of the Roadcraft Manuals there is an over riding safety proviso in that one should always drive or ride at speed that one can stop in the distance seen to be clear and on your side of the road. That is paramount to all safe use of the roads. If we are behind the vehicle in front by only 30 ft and only doing only 30 mph that may appear safe as we can anticipate in traffic that the vehicle in front will have to eventually slow and to stop at sometime and therefore if that vehicle slows, showing brake lights then we can do the same and many drivers therefore believe, mistakenly that that small distance is a safe distance to give but if that vehicle was hit by a car emerging from a side street and therefore came to a sudden and unexpected halt directly in front of us then 30 ft just doesn't cut it, we will be unable to guarantee to stop in such a small distance so we will collide with it.
That is why we have a table of speeds and distances that are recommended in the H.C. or by the DVSA for stopping in.
What has that to do with the limit point.... everything. Lets give an example, its a left hand bend and not too tight and the limit point is in front of us but over to the right side of the road where both verges meet. The visible distance from us to that point is say 100 ft. and we are doing say 40 mph around that bend following the recommendations of training to the limit point. Under normal conditions of a dry road, level and with good brakes what is our safe stopping distance on the straight ? At 40 mph the recommended safe stopping distance is 120 ft so we are now following the recommendation for the optimum safe speed for that particular bend by using the limit point only ? ON the straight it will take us 120 ft to stop in but our distance is only 100 ft.and we are on a bend. Add to that the fact that on a left hand bend we also see quite a bit of road space over the middle white line on the opposite carriageway and that may mean that we are actually seeing about 30 ft of road on the wrong side of the road that we cannot use.
So our safe stopping distance reduces again, from being a recommended 120 ft. but we know we only have 100 ft at 40 mph and it now becomes only 70 ft. at best. Do you thing you could stop in that distance should the need arise? I think not. There is another problem, its that stopping distances in the books are on the straight and not on bends where there are other forces that the driver needs to take into account. Available grip is one of them together with centrifugal forces. Grip is being taken up by driving at speeds around bends and so lets imagine that some 30% of grip is now being used up on bends leaving only 70% of grip available to you. Whilst you can use 100% of braking power on the straight your braking power that is available to you you is now compromised by being on a bend. As a result you no longer command 100% of braking capacity., Lets say only 70% but that means that you cannot hit the brakes as hard as you would on the straight as more than likely you will lose traction on the rear or front or indeed on all the tyres thus losing complete control of your vehicle. So unable to bring the vehicle to a satisfactory halt due to the reduction in braking power your stopping distance on a bend has been compromised and your safe stropping distance will be more than the 120 ft. associated with your speed of 40 mph.
So its not just a case of limit point distance at all. Merely accepting the limit point on any bend can give a false impression of the amount of road and therefore speed that it is safe to travel at. It will only give you your optimum speed for that curvature but its a completely separate item from the golden rule of safe stopping distances. If you read any Police Roadcraft Manual you will see that on bends where they recommend the limit point they also continuously remind one of the need to give sufficient safe stopping space in font of one to be able to stop but it appears that many training organisations have failed to see that safety point and place to much reliance on the vanishing point to the extent of failing to remember the first golden rule of all safer driving.
Get your own channel, spouting off on other people’s as if your opinion matters.
A couple of minor things to add . . . 1) pre-load the front tyres - a tiny dab of steering into the bend just prior to full steer "warns" the tyres just prior to the full steer and begins to load the suspension to improve balance through the bend. 2) Position (off-siding) - in the UK - for a left hander, the further to the right you can safely take the car (i.e. over the dashed white line - not solid white) the better your view of oncoming hazards and opens up the limit point, for a right hander - as close to the kerb you can safety get. And 3) for front wheel drive cars - a small dab of left-foot braking puts load (load = grip) onto the drive wheels and helps set the car up for the exit (balances a variable 4WD system too - and very important for 911s with all that weight hanging out back!). All actions as gentle and as smooth as possible to allow the car and its suspension to adjust to the change of force - think of a diver entering the water, the best dives have the smallest splash.
For 2) remember the adage - "the more white, the more shite" - so take cognisance of the length of the dashes and any other white in the bend's vicinity.
Advanced driving is a funny thing - your passengers won't notice it, it should be invisible to them; you got them to their destination quicker and safer but they had no idea, they never noticed.
A day's training with someone like Reg is, well for one it's a fantastic day out because these people are inherently highly-knowledgeable motoring enthusiasts, but more importantly it brings so much benefit (although I haven't trained with Reg, I have with Steve Cot in the Bolton area). Because driving is such an everyday thing, drivers invariably think they can do it as well as possible - and they can to a certain extent, accidents are few and far between despite the newspaper reports. That said, we've all been behind drivers who hold their vehicle on the brakes all the way down a hill, or they entered/exited a bend far too slowly and a myriad of other minor transgressions they never knew someone else noticed. Holding back slightly on a country road to watch how a slower driver in front is observing the white lines and the traffic around him or her - just to be sure you're not going to be side-swiped is another one, or considering how fast you have to actually be going to safely make the over-take and safely scrub the excess speed before the next hazard is important.
No offense but on your point about stopping distances that are lower in reality, what if there's an oil or diesel spoilage in the middle of the corner, or as the country I live in, the roads are not as perfectly kept up and there's a pothole in the middle of the corner that you can't see from the distance and could possibly damage your tires and suspension? also what should I do if my car is older and doesn't have esp and a sophisticated suspension? should I be braking mid corner or drive near the traction limit?
Never let your ultimate stopping distance point vanish round the corner or over the hill or behind that bus etc etc
Hmmm I'd like some brakes that could stop in a car length (15ft) at 30mph (44 ft per sec.). This would give 2G deceleration from a car only holding the road with the 1G of pull from good 'ole mother earth (ie 200% efficiency - a physical impossibility). Correct figure is 1G deceleration derived from 1G of road holding (100% efficiency) which equates to approx 30 ft @30mph - 120ft@60mph - 480ft@120mph + 22ft for every 0.5 sec of reaction time. It must be remembered that these apply only in the dry (film looked damp) & only in a straight line - if on an apex you pull 0.2G lateral accel. you only have 0.8G left to brake with (tyre grip trade off) so 30-0mph in 38ft. Similarly over a crest the car loses "weight" & therefore grip but still has the same "mass" to stop.
When comparing Highway Code distances it should be born in mind that a car only needs brakes that can achieve 0.5G brake force (60ft @ 30mph) to pass the MOT - at 45ft the Code is simply splitting the difference between best possible & legal minimum brake performance.
That said most people over estimate how much distance they need and this is otherwise another fine video with professional production values and a professional and erudite presenter who espouses (like all ex. & experienced serving bobbies) nothing but common sense.
Not sure why you thinking breaking is connected to earths gravity thats not how friction works if I have a block of rubber with groves in it sitting on top of tarmac with a non smooth surface the force required to overcome its friction pushing sideways can be theoretically many times higher than the force of gravity acting on it. Your logic isn’t sound and is not how g force are limited in braking and acceleration many sports cars can get over 1.3GS in braking and f1 can create 5GS in deceleration/cornering and top fuel dragster can pull 8gs when launching although will pull an average of 3GS throughout their run.
If you want you can do the XUVAT equation for top fuel dragsters and come to the figure yourself if you still deny it.
@@PiOfficial Dragsters do a tyre burn out to melt the rubber to a sticky goo giving several times the traction co efficient of a standard tyre and have a big wing to press down with several times their weight at top speed. same for F1 car. ie weight is supplemented by aerodynamic down force giving several g of tyre grip & super sticky rubber. Sadly every day folks cars aren't of quite the same calibre - a "g"metre or traction circle graphic if fitted to an "ordinary" car would only go up to 0.9g before showing a cautionary red line as on a rev counter. I will grant that the co-efficient of expensive modern tyres when new may be 1.2 - 1.3 (dry) allowing a similar g force but again the average road merchant is running 5 year old hardened budget rubber with only 3 to 4mm of tread. My original comments referred to road cars. As an interesting aside without its brake parachute how long would it the dragster to stop on its wheel brakes alone given that (i'm guessing) it has no front wheel braking on those bicycle wheels they have at the front? Best regards.
@@aztimms you can’t cop out like that buddy. You were saying that breaking g forces can’t be greater than the 1 gs of gravity. Yet race cars even before aerodynamics quick ie from a standstill can have tyres with a friction coefficient more than 1 which allow acceleration beyond 1 g and therefore deceleration as well
That car doesn't half make some lovely noises.
It is complex - when you are driving and watching a number of things - signs, road conditions, other drivers and vehicles, mirrors etc. - to look at a limit point and figure out if it is moving towards you, staying the same, creeping or firing away - it is much simpler to thnk in terms of "Can I see what is coming around that bend and will I be able to react to it at my current speed?"
Although it means the same thing, it is more intuitive than to think consciously in terms of limit points. I find I get locked into the limit point and forget everything else around me when I do - especially when at speed. So I do not think of - is the limit point staying, coming at me or running away.
Now you've got an M2, you're gonna need a faster drone.......... ;-)
G