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A PHYSICIST WRITES . . .
(June 2009)
If I put down some questions that are niggling me, perhaps they will go away...
In April, our editor [Thames Valley Group Newsletter] discussed the intrusive and distracting hatching to be seen on roads in increasing amounts against the left kerb, bordered by a solid line, before a junction or roundabout. Later, he and I tried to agree on whether or not driving over it is specifically forbidden. The Highway Code doesn’t say, and even the really official Traffic Signs Regulations are not entirely clear.
I consulted Peter Rodger, Chief Examiner of the IAM, who advised me that it is an offence to drive on to any road marking with a solid white line around it. And anyway, surely the intention is that junction hatching should be forbidden territory, like solid-border hatching along the middle of the road. If so, then plainly most drivers are unaware of this or ignore it, because hatching near junctions wears away faster than any other road marking! Hence my first niggling question: if a particular stretch of hatching has largely disappeared, but you know where it was, does the legal prohibition remain?
[In fact, I’ve since been told by the Department for Transport that it’s not an actual offence to cross hatching bordered by a solid line (hence this is not referred to in the Highway Code) — except when it lies between central double white lines, as these always keep their significance. But I still worry about worn-away road markings generally: how far are you legally obliged to obey your memory of them?]
When you arrive at a bend in the road that has reduced visibility around it, the recommendation is to move towards the outer edge of the curve (within your lane) in order to obtain the best view of what may lie ahead. But as the book Pass Your Advanced Driving Test says: “Avoid going too close to the verge — and tick yourself off if you feel your offside wheels touching the central cat’s eyes.” My problems in a nutshell! If I’m focusing on the tricky task of lining up the car just inside the outer curve of the lane, how can I possibly give the necessary attention to things in the distance?
Suppose now that you’re on a major road or motorway, and approaching an entry slip-road. My feeling is that you need to be aware of whether it comes from a relatively minor road, or from one that’s ‘equal in status’ to the one you’re on (eg, another motorway linking to yours). Vehicles on this class of slip-road are more likely to be travelling at your speed or faster, and are less likely to give way to you. Therefore you ought to keep a sharper eye over your left shoulder, as you decide whether to move over to the next lane (if you can).
Here’s the question: I often drive northward up the A3 towards Guildford. At Hog’s Back, just round a bend, the A31 traffic joins the dual carriageway from the left — thick and fast, but invisible until the last moment! There’s only a small sign to warn you of this slip-road, though I would guess that 98% of drivers on the A3 know it’s coming. To me, the obvious thing to do is change lanes early every time (if I can). But why do I never observe anyone else doing the same here? Instead I see skilful interlacing of vehicles in the left-hand lane at high speed, plus some late swerving into the outer lane or else braking on the slip-road.
On motorways, you also have to be aware of approaching exits: we’ve all seen cars cut across from an outer lane at the last minute, aiming for the slip-road. The gap they find in the traffic is often so narrow that you would think they have only about a 50-50 chance of succeeding in getting through, on average. But this implies that half of such manoeuvres fail, with the drivers being forced to continue to the next exit. In which case, why do they take the risk of staying in the outer lane, at all?
The current format for number-plates has been in operation for eight years now. It has some ‘good’ points: a leading R indicates a car from the Reading area, and the two digits give the year of registration — at least they do for those vehicles registered from March to August. As for the others, in a few years time will you easily recognize ‘59’ and ‘60’ plates, say, as having been issued around 2010, before and after the ‘10’ period?
But the most important bit of the registration, surely, is the three random letters: these offer many thousands of combinations for narrowing down the identification of a vehicle when necessary. Why then are the three letters placed at the end? How many people would think of trying to read an escaping number-plate from right to left?
A while ago I discussed the rule for driving in Spain if your eyesight needs assistance: you must carry a spare pair of spectacles in the car. This is a good thing to do anywhere, though I pointed out that you really need two spare pairs (in Spain) because otherwise, supposing you had broken your regular glasses, you still wouldn’t be in a position to drive on — think about it! But here’s a further thought: are you exempt from having to carry spare specs if you are accompanied by a spare driver? I can see no logical reason why this should not be so, but I bet it isn’t stated anywhere as an exception to the rule.
The majority of UK voters are vehicle-owners. How is it that they fail to form themselves into a unified and overwhelming voice against the imposition of ever-increasing taxes, penalties and physical restrictions on the use of vehicles?
Finally, a question that is niggling me no longer! Earlier in the year, you may remember, I asked whether the marker posts every 100 metres on the M25 get gradually out of step, between the two carriageways, because of their different circumferences.
Well, a highways consultant tells me that motorways and other roads are usually laid out by reference to a so-called ‘master string line’ along the central reservation (or down the middle of ordinary roads). This includes the distance markers — hence they do stay lined up, as they march around the M25. OK then: how big (initially) was the rolling ball of 120 miles of master string? **
Peter Soul
**Not much more than a metre across, is my estimate (but of course I’m joking: probably the string came in 100 m lengths).
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