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A PHYSICIST WRITES . . .

(July 2008)

I have no particular theme in mind this month, so I will offer you some random thoughts in order to clear them out of my cluttered-up brain:

Urban roads are littered with official devices supposedly intended to impede traffic even if only briefly, notably bottle-necks and square pillow-humps. But bottle-necks work only if two vehicles arrive simultaneously so that one forces the other to stop. How is this consistent with considerate and courteous driving?

As for pillow-humps, these are placed in the centre of the lane, positively inviting you to take them symmetrically without slowing down. But think what this does to your tyres: the sloping sides of the hump severely deform the inner shoulders of all four tyres, around most of the circumference.

How can such treatment not be causing progressive internal damage? Having realized this, I now try to run one pair of wheels over the body of the hump (slowing right down, of course), which compresses the two tyres just in one line across the tread. Then at the next hump I apply the other wheels. But I canít shake off the feeling that drivers behind think Iím crazy.

Catís-eyes are designed to be self-cleaning: every time a tyre goes over them, the rubber housing wipes the surface of the glass. But what about ones that are located between double white lines? Naturally these catís-eyes are never run over by a wheel. If when driving at night you notice that a line of them are reflecting back at you less brightly than they ought to be, surely it is your public duty to move towards the middle of the road and give them a polish up?

From many hours spent browsing the titles in second-hand bookshops with neck bent at right-angles, I am able to read upside-down print (especially capital letters) fairly easily. But this does have disadvantages when I am driving. If I arrive at an upside-down NO ENTRY at the end of a road or a traffic lane, I find it hard sometimes to decide whether it applies to me or not!

Similarly, when I am walking up to a carriageway crossing where they have helpfully painted LOOK LEFT (for traffic), I notice that Iím influenced just as much by the inverted LOOK RIGHT on the opposite side. Oddly enough, though, back in the driving seat I find that a SLOW in the oncoming lane looks more like MOLS to me (as it probably does to you).

In fact, the human brain has evolved so as to be able to recognize and respond to a huge range of patterns and shapes. As I explained some time ago, much of this brain-work happens subconsciously, before the images that your eyes pick up are finally transformed into the picture that you consciously Ďseeí in front of you. To put it another way, you donít always have full control over what your attention focuses on. Catching sight of of a new model of auto for the first time, for example, you might be unable to take your eyes off it. But what I want to complain about is something more specific: vehicle lighting.

I have no problem with Ďnormalí lights that are either roundish or vaguely square, as long as they are not too small or bright or dim. Side and rear lights that are particularly faint cause me to concentrate hard on them, though this is probably just as well, or I might lose track of them in the darkness. Small and bright headlamps, on the other hand, attract my gaze when Iím trying hard to avoid looking at them.

But thereís worse: recently, much against my will, my attention has been caught by lights of more unusual appearance, both front and rear. They include triangles, rings, thin lines (both straight and bent) and lights with dots or intricate shapes within them.

These are all things that the brain reacts strongly to. Itís the eye of the car-buyer that they catch first, of course. But once they have done that job successfully and have been launched on the road, they get to work on me! I find them intensely distracting and annoying, and I am surprised they are permitted.

Last November I mentioned that Peter Rodger, IAM Chief Examiner, had given me a straight answer to a question on amber traffic-lights. You may have seen the Q and the A later in the Advanced Driving magazine. He explained that regardless of the instructions in the Highway Code, in simple terms all that the actual regulations say is: when amber appears, stop if you can do so safely, or drive on if you canít. But then as a sort of footnote he wrote: ďWhen approaching a green light ... the longer you can see it is green, the sooner it will go amber. So there isnít much excuse for crossing amber.Ē

This seems to be advising that on a long green I should slow right down, just in order to be ready to stop short if it changes! Might not following drivers view this as being obstructive? Letís consider a better-defined scenario: suppose Iím coming up to a familiar junction, and there are clues telling me that green will change to amber a second or so before I reach the line, assuming I keep my speed up. Knowing this, should I slow down and prepare to stop (if I can do so without being obstructive), or should I press on?

Your response to that one may not be in my favour ... OK then, if the lights happen to be red as I approach the next junction then maybe I shall be able to make up some of the time lost, by slowing down early and keeping some momentum (in other words, doing what Peter Rodger seemed to be advising, but on a different colour). Because if I can manage to arrive at the line just after green appears, I shall gain a substantial and perfectly legal head start on myself (and others) ó and, if you think about it, I shall save some fuel too.

[See my February 2009 column for further discussion of this manoeuvre.]

I see that a theme has gradually emerged this month after all: looking, seeing and reacting!

Peter Soul

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