The Limit (or vanishing) Point - is it enough?
As soon as we take a look at post-test motorcycle training, one of the concepts we're likely to come across is something called the Limit Point or the Vanishing Point (or Convergence Point or Visual Point - call it what you like, it's the same thing). It gets particular focus in UK-based post-test training because it appears in the police handbook 'Motorcycle Roadcraft'. And because the police manual discusses it, it's a feature of the IAM's own RoadSmart 'Advanced Rider Course' and in the training delivered by RoSPA instructors and virtually anyone else who bases their training on UK police practice. Not surprisingly, it also regularly pops up on advanced riding videos and guides in magazines and on the internet. It's also been adopted abroad. So just how useful is it? And just how do we set our speed for a bend? Is it ONLY based on 'limit point analysis'?
Because the Limit Point has been explained so many times and done to a crispy turn on the internet, I left it the topic alone for many years - why add another article to an already-sizeable pile that say much the same?
So what changed my mind?
Have a read of this. It's a post made on the bike forum I used to moderate by another advanced instructor with impressive ex-police credentials:
"The main thing you have to learn about safe riding is the visual point or vanishing point. I teach this to clients all the time. Some tell me in detail how or what they look at at and when I take them out on the road it seems no one understands it too well. All police riding is based on this because if you know how to use it, it gives you everything you want. Position on the road, speed on the approach to any bend, how fast you can enter the bend, how much power to apply to the throttle, where to move the bike from the corner for the next position. In my experience it is not the technique that is hard but the believing what you see and having confidence to use it anywhere in the world. It is very exciting once you know how it works."
The writer continued by explaining the 'stop in the distance we can see to be clear' rule, and explained that as the limit point is as far as we can see, that's where we need to be able to stop.
Except it isn't.
Firstly, it's assuming that any obstacle in our lane revealed by the receding Limit Point will be stationary. Of course there's no guarantee that's the case as any biker who has ever misjudged an overtake approaching a corner and gone into it on the wrong side of the road will know. The narrower the road and the tighter the corner, the more likely we are to encounter a vehicle crossing into our lane, and in the worst case, driving towards us in it. It's important that we add the extra words that are actually clearly stated within 'Roadcraft' - and that is that we must actually be able to "stop WELL WITHIN in the distance we can EXPECT TO REMAIN clear". That's a significant difference.
Secondly - and this is not mentioned explicitly in 'Roadcraft' - there's always the possibility of an oncoming car turning across our path. Now, if we're rounding a left-hander, we'll see that car appear a few moments before we can see the junction it's aiming for on the inside of the corner - our line of sight always unveils the outside of the bend before we see the corresponding point on the inside of the corner. What that should tell us is that we won't know if there's an emerging car on the inside of the bend, even though our formal Limit Point is already beyond it. The reverse applies on a right-hander. We'll see the junction to the inside of the bend, but the oncoming vehicle about to cross our path into it will be out of sight. Just as 'Roadcraft' says - without explaining why - we MUST be able to stop well before we reach the Limit Point.
Here's a third issue that isn't mentioned either. Let me introduce you to what are sometimes called 'Surprise Horizons'. A Surprise Horizon is any point which lies between us and the Limit Point, from which another vehicle (or cyclist, pedestrian or even an animal) MIGHT EMERGE and BLOCK OUR PATH. And that means we actually need to do is be able to STOP at that point, NOT at the Limit Point. And that is a very different concept. The term Surprise Horizon comes from a book called 'Mind Driving' by Stephen Haley, a car trainer.
Even though we might have a clear view of the Limit Point itself, a Surprise Horizon can lurk unseen in any blind area. Even on a near-straight road, a slight kink in the hedge, the narrow gap between two buildings, an opening between parked cars, or a blind crest all have the potential to conceal anything from a tractor tugging a trailer to a sheep.The Surprise Horizon concept is one that really should be added to 'Roadcraft' and to any explanation of how to apply the Limit point concept to judge speed. If we simply see the road as guaranteed to stay empty between ourselves and the Limit Point, we really are risking a nasty SURPRISE! And remember...
No Surprise? No Accident!
Kevin Williams
Survival Skills Rider Training...because it's a jungle out there
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