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A PHYSICIST WRITES . . .

(September 2010)

Motorists can be divided, I suppose, into two groups ó a small Group A: those who drive in a manner fairly similar to me, and a large Group B: those who donít. When I say similar to me, what I mean is that I aim to drive at the speed limit (when itís safe to), I approach junctions, hazards etc slowing down early with minimum braking to save fuel and brake linings, and I accelerate briskly as this too saves fuel, because putting your foot down (without actually over-revving) is the most efficient way of burning the stuff: see my September 2008 column.

(Applying my best logic to all this, I arrive at the conclusion that the really fuel-efficient method of travelling at speed would be to switch between foot up and foot right down, either rapidly or more leisurely according to preference! However, this would be tedious for the driver, uncomfortable for passengers, and dangerously confusing for other road-users.)

Another habit of mine is that if Iím being followed at too close a distance for my speed, I ease off gently and then accelerate hard for a second when the tailgater perhaps least expects it, to increase the gap. With luck (see January 2007) he or she will get the message. And there are other messages too that I might want to send to any of the Group B contingent: my early deceleration may need to be signalled with just a flicker of brake lights, for example.

As for sticking to the speed limit, surely itís better for drivers following me to be aware that Iím doing this, rather than just dawdling, so I make a point of altering speed quite sharply where the limit changes upwards. And when the road is clear ahead, to be honest I generally try to place the needle at just above the limit. I know that my speedometer reads high, possibly higher than in vehicles behind, so again Iím making sure that their Group B drivers donít see me as a slowcoach travelling at below the limit.

While Iím on the subject, would you agree with me that speed-limit signs ó letís say 30 mph ones, with 50 on the reverse ó tend to be installed some distance before the point on the road where you might judge that the traffic needs to be down to 30? My guess is that this is quite deliberate on the part of the authorities, who probably argue that many drivers wonít slow down until they reach the sign, and if going the other way they will already be up to 50 by the time they get to it.

Even for me the temptation is to split the difference and pass the sign, either way, at 40 (Iím not saying I do this, mind). But hereís a curious thing: the official Traffic Signs Manual from the Department for Transport gives a wealth of guidance to traffic authorities on putting up signs and laying down road markings, yet thereís no reference at all to the wisdom of locating speed-limit signs just a bit further out of town than where the slower speed is actually required (for the reasons I mentioned).

The Manual does contain some speed-limit puzzles of its own though: ďNew Speed Limit signs must be removed within six months.Ē Really? Around here they stay up for at least two years. ďCountdown signs giving advance indication of a change in the limit are not prescribed and must not be used.Ē But Iíve seen these in several parts of the country ó and they certainly encourage you to slow down early.

Then thereís a picture of a special sign that you might come across in cities: ďThe diamond sign shown indicates the speed limit for tramcars in km per hour.Ē I can only think that this is because our tramcars are manufactured on the continent and it would cost too much to have their speedometers re-engraved in mph. Well, do you have a better suggestion?

Now let me start again and divide people (not just motorists) in quite a different way ó Group A: those who donít drop litter, and Group B: those who do. Iíve long thought that the Group B lot live in another world ... the problem is that it overlaps with our Group A world and spoils the look of the place.

Then early this year I had the idea of trying to get a few local residents each to volunteer to keep their own road (or a manageable stretch of it, or a nearby footpath or green space) reasonably clear of litter, here in Earley on the edge of Reading. With the strong support of our local councils, residentsí association and environmental group, the Earley Adopt-a-Street Initiative was born: EASI for short. And you wonít believe this any more than I do, but already it has nearly seventy litter-picking members! I canít resist labelling them Group A1.

Our equipment (bags, picker-tools, gloves, yellow vests) is supplied by the councils, who will of course also deal with any localized litter problem if itís serious ó but they canít possibly do what we can, along all our streets, just by going out for half-an-hour when it suits us.

We in Group A1 try not to think about the Group B culprits, but itís obvious that they comprise both pedestrians and motorists. The latter empty their ashtrays and jettison fast-food containers. As for those on foot, not only do they drop cigarette-ends and food rubbish too, but they also seem to delight in slowly tearing up paper and packets into tiny pieces and discarding them as they go.

All this is both mindless and illegal, and is unlikely to stop until education and law-enforcement become effective. However, it has been proved scientifically that a clean street is at least some deterrent against the dropping of more litter.

Anyway, as I say, we ignore Group B as we carry out what can be a satisfying task ó really. And if you take a look at the LitterAction website you will discover that there are hundreds of other anti-litter teams hard at work, across the country. But I like to think that my group will stand comparison with most of them, considering its A1 achievement!

Peter Soul

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