You read through books and publications on advanced driving and look for keys to the sound knowledge of the author. One of these, of course, is to look for System. An even better indicator is how they suggest speed is reduced. But another is to seek out their views on positioning and what its basic precepts are.
It is interesting that very few writers seem to really know about this. Yes, they gleefully talk about positioning for one reason or another; and, of course, positioning for bends in which view is often considered paramount; often a measure of stability is thrown in for good measure and probably more so if they have a rallying or racing background.
But what are the foundations on which good positioning is built? You will find them In Roadcraft, but couched in the current terminology by which it loses clarity of meaning. In fact there wasn?t a chapter specifically on positioning until the much revamped 1977 edition. Here, in the introduction to the chapter, the two main points came over more clearly. But much of this was, and still is, covered at Police Driving Schools, particularly Devizes. There they make specific reference to safety, view and stability as the basics of positioning, particularly for bends. On top of that they go into the subject in some detail. But it is important to understand that the basic principles of positioning do not apply just to bends; they apply at any moment in time on the road.
THE BASICS
Firstly let's look at positioning for stability, because in many ways this is the simplest to deal with. At a rough guess a vehicle travels in a straight line for perhaps 50% of the time; for the rest it is on some sort of curved path with the associated forces acting upon it. A vehicle is also in its most stable configuration when travelling in a straight line and the basic rules of acceleration and braking are also ?in a straight line?. So it certainly makes sense to look for situations where the vehicle can be kept in, or close to, it?s most stable configuration for as much of the time as possible. There are also less stresses on the suspension, less wear on tyres and it is generally more comfortable for the passengers. Where the performance of a vehicle is concerned then stability is a factor the driver should be conscious of all the time and that is related to the important subject of 'Forces acting on a vehicle in a curved path'. Of the three stability is perhaps the easiest to deal with because it is always subservient to the other two.
Safety and view, however, cannot be taken as separate entities. In fact the subject could be a perennial one because of the interwoven affair between these two. It?s a sort of love/hate relationship. Each one may have a good reason for taking priority at any moment of time; but the only certain thing is that safety will always win if there is a clash of interests. There are, however, many situations when getting the view will assist safety because we can then see and plan further ahead, but we must always remember that this has the proviso of safety added to it. And so it goes on. Do we maintain good view here or sacrifice our position for safety? Should we position for safety here and loose our view together with the observation and planning which goes with it?
You have the ?heavy? parked on the nearside blocking off view down the road. You will have to go over the centre line in order to overtake it. Do you go closer before trying to get view or, do you get view earlier which enables you to get a better assessment of road conditions further down and make an earlier decision on whether to wait or go?
Ahead is a blind junction on the left; no pavement to give you a buffer zone so lets be well away from this, in fact up to the centre-line would be good. That will be the safest position and also the view into the junction will open up that much earlier. Ah, but now you see the cyclist coming the other way and the on coming traffic setting up to overtake it and overstep the centre-line. What is your decision now?
FOLLOWING
A particularly good example for the relationship between safety and view is found in the following position. The further back one is from the vehicle in front the better the view for both observation and planning. But equally, if not more importantly, the better the chance of pulling up safely if the one in front does an emergency stop. Of course being further back means you have a chance of seeing in good time what the driver in front pulls up for at the last moment. In this case it's a good example of safety and view complementing each other.
BENDING IT?
However, the classic examples for safety, view and stability are found on bends. Firstly we have the right hand bend - and we assume these are closed bends.
The ideal position on the approach to a right hander is, as we know, to the nearside - but why? The first, and most common reason given, is for view; fair enough. Obviously the view will open up earlier by virtue of taking this position. If you ask people to develop this, they may then come up with some rationale based on stability because obviously from a nearside position it will be possible to make the curve through the bend less severe than the bend itself.
So far so good. So where does safety come into all of this? Is it because if we can get our speed right we can stop in the distance we can see to be clear; by being on the nearside we can see further through the bend and therefore have an earlier view of a hazard ahead? Well one cannot argue that that is an important aspect, but it is not really what safety is about in this context. When we talk about positioning for safety we are generally referring to the lateral positioning of a vehicle in its half of the road and the related threats to its safety.
If you stand near a bend and watch people driving through it what sort of line do you see on average? Would you say they oversteer slightly, in which case the line will be tighter than selected or, do they understeer and go wide of the line chosen. Almost without exception you will find the latter is the case. Often you will see additional steering being put on as they go through the bend to compensate for the developing understeer. Bear in mind that understeering vehicles are instinctively easier to control. As far as I know all vehicles are designed with initial understeer for that same reason; additionally front wheel drive vehicles have inherent understeering characteristics anyway; even if car designers do try to disguise this. The picture unfolds.
Now let's look at the average persons ability to judge and adjust speed for bends. Do you think it?s fairly good or not? Add to that drivers who tend to use the performance of their cars, or lorries (!) and what then? Well obviously the exit area of a bend is one where the danger is potentially greatest. So in ideal circumstances where would you like to position your vehicle now on the approach to a right hander when looking at safety? Yes, you would like to be as far away from it as possible wouldn?t you, which means on the nearside.
TO THE RIGHT...
Let's go back and look at safety, view and stability in relation to this straight-forward closed right-hander. The ideal is to position on the nearside for safety. It also happens that this is a good position for view and additionally it is a good starting-point for stability.
But now we are approaching a similar bend with a junction on the nearside, what then? Well obviously it would not be prudent to position so strongly to the nearside, but you also still have the offside threat of vehicles exiting wide from their left hander. So reasonably a centre-line position might be best. But, having moved further to the right what happens to the view? Obviously it?s reduced, which means less view through the bend and that affects the limit point, so speed might need to be further reduced. In turn this revised position for starting into the bend will affect the line taken through the curve and that will affect stability. So here are two reasons for reducing speed, view and stability. But it might also be prudent to have a reduced speed in case anything jumps out from the junction on the left; so that you have more control if the unexpected happens. And back again we come to safety being at the top of the list. This means that for a right-hander we position to the nearside for SAFETY, VIEW & STABILITY, subject to any nearside dangers.
..AND TO THE LEFT
Now what about the left hander, bearing in mind that the view to your side of the road opens up last here? A strong offside position is clearly ideal; it?s obviously a good position for view and, indeed for stability. One might also reason, it is good for safety because you are on the offside part of the road away from any junctions which might be on the bend. But, generally junctions on the inside of bends are not nearly so prevalent as oncoming traffic over the centre line. Apart from which you will normally see a warning sign or a finger-post pinpointing such a junction. So the major threat here is potentially from oncoming traffic.
Here again, looking at average driver behaviour; if people are coming into a bend too fast they tend to turn in early. This means a shallower line and often to overstepping the centre-line; but generally nearer to the apex of the bend rather than at the back of it.
So, on a left-hander it is important to sacrifice the position for safety if there is subsequent oncoming traffic over the centre line. In summary, the position here is to the offside for VIEW & STABILITY, subject to SAFETY.
And that's only dealing with closed bends; getting onto variations of open bends expands the permutations considerably. On top of that add in all the various options you find in town and other road conditions, whip them up in a blender and you have variations which will keep you going for ever.
CLEANING UP THE LINE
However, before leaving the subject we had better deal with the perennially thorny subject of 'straightening the line' which often involves overstepping the centre line. I have seen it done well and safely, but I have also seen it done badly which means potentially dangerously; often by those who do not properly understand the subject and who want to show just how good they are!
Again, as always, the underlying principle is, 'Is it safe? So in examining the safety aspect we will look at where we might be most vulnerable.
However before that, let's look at the advantages of 'cleaning up the line'. Many will justify it by stability. Fair enough, there are less lateral forces acting on the vehicle and that has to be a more stable configuration. On top of that it will principally be more comfortable for passengers. Certainly if any real progress is being made, then stability may be a major factor; the less lateral forces and weight transfers the better.
But what about view? The one thing we should know by now is that better view means seeing further ahead means earlier observation means earlier planning etc. And better view can also, and very importantly, mean an earlier decision not to go; so there is certainly a good a case for view and improved forward observation (as the term goes). This can also mean enhanced safety because more information is gained earlier on which to make a decision. Additionally, in some situations, you not only maintain the view but cleaning up the line conveniently puts you further away from a potential danger on the nearside if there is nothing to threaten you on the offside.
The big question is 'can all of this be achieved and at the same time be consistent with safety? If it can't it is not on, period. So what are the major dangers to look out for. Well danger may lurk anywhere there is restricted view. Considering that, in many instances cleaning up the line will be done in open road conditions, there will generally be no pavements and the hedge line may come straight up from the side of the road. So this makes these 'closed' rather than 'open' bends. This is the worst possible scenario and therefore the one which we should look at most closely. The closed bend environment also means blind entrances on to the road with all the associated dangers that those offer. Nearside, blind junctions are bad enough, but offside ones are even worse as you will come to realise when we deal with overtaking.
So the major area of danger is going to be blind off side junctions or entrances which are tucked in at the back of a bend. In other words they are, on the approach, initially obscured from view until you can see past the apex of the bend. And this is what you have to be very careful of when straightening the line. There is no value in having all this view down the road and the stability which goes with it if you haven't checked all the blind areas as well. A good summary of this is to be able to see all the road surface for some considerable distance ahead. And always remember the maxim; 'So long as it is safe'.
Police traffic vehicles (for that is the general public's perception) are in the invidious position of being looked upon as the example to follow and, ideally, the epitome of all which is written in Roadcraft. Unfortunately, they get hung by their own petard and, understandably the drivers and driving schools have become particularly sensitive as a result of it. The problem they face is that having studied how to do it properly if they straighten the line they will also have checked all the factors before hand. The average road user seeing this will say, 'Ah ha, so that's the way to do it', and proceed to clean up the line willy-nilly with potentially disastrous consequences. As a result police driving schools have a mandate not to do it if anyone else is around, which is also understandable. And of, of course, this has permeated through to the advanced driving organisations, which is equally understandable.
Just so that it is in print, it goes without saying that cleaning up the line at no time involves overstepping continuous white lines.
From your point of view know and understand the basic principles well, and if you are going to do it check it is completely safe beforehand. Then, in principal, you can't go wrong. But if you are not sure about doing it safely then don't even think about it.
JUGGLING THE GREYS
As you can gather, part of the fun and the mental stimulation of driving is in the constant analysis and decision related to safety, view and stability. Very seldom does any one of these stand completely on its own; you are forever juggling them around in their respective grey areas.
It's more a-kin to a mobile chess game, but build in a reasonable measure of unpredictable behaviour, such as is generally found on the roads, and you can add a bit of Russian Roulette for good measure. It should give us enough mental exercise for the time being.
Now where was I? Rook to King's Bishop three and which one has the gun?
Nigel Albright
01392 874491
Authors note:
Devizes Police Driving School is no longer in existence. It was the original ?regional? police driving school which started in 1946.
Mark - as email.
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