Tag Archive | "satellite navigation"

Maptastic Days Are Here Again

Somewhere in the bowels of your car there may be a symbol of the great days of real motoring. Hidden away, like the Dead Sea Scrolls, at the back of your boot or under the back seat you might well find – a dog-eared paper road atlas. Technophobes will be familiar with this archaic form of direction finding, often used with limited success by your dad. Technophiles will not understand this reliance on map reading skills when there is a perfectly adequate device on the dashboard to do the hard work for you.

The sat-nav, like sliced bread, has been one of the great inventions. They have never been cheaper or better featured. They are programmable and settings can be altered to suit. How can something so small be so clever? Well, that’s the official line, but there’s an unspoken issue. Your Editor, whilst being forced-marched on a health inducing walk high up on Barbury Castle in Wiltshire, came across a nonplussed German driver coming up an ancient track in an expensive car. Being a man, he blamed, in halting English, a ‘broken GPS’. Therein lies the problem.stuck Maptastic Days Are Here Again

The news is occasionally filled with giant lorries becoming trapped in villages because their device directed the driver down a country lane and they blindly obliged with the inevitable result. Sat-nav’s are great but they are not infallible. Neither are drivers. Especially not drivers. Despite the fact that the chosen route is clearly unsuitable they follow it anyway. Simply by turning round and forcing the device to ‘recalculate’ would probably solve the issue.

This is why more than half of the UK’s experienced drivers still prefer to use maps. Real map-reading is a disappearing skill (which should be taught in schools) but most motorists can understand a basic road map once they’ve got it the right way up. Older drivers with more than twenty five years of driving under their belts prefer to stick with maps. This is according to a recent national survey by a road rescue organisation.

As mentioned above they mistrust some of the information but what they hate most is the constant babble of instructions. The survey mentions that just forty five percent of respondents owned any form of sat-nav at all, whether portable or built-in. That’s a surprise. We are led by promotions and advertising to believe that the latest thing is indispensable to our lives and yet here we are still relying on ancient texts to move about the country.

Many people have no problem with sat-navs. If kept up to date they can guide drivers through complex and hitherto unknown one way systems; they can place a car within ten metres of the required destination whilst avoiding toll roads, ferries and traffic jams. What’s not to like?

On the other hand, it is quite nice to know that some things never change. Maps bring out the pioneer spirit in motorists. They can take married couples to distant lay-bys for spousal arguments about the innate inability of women to read maps, for example. It’s true. There is something special about a map and the more detail on it the better. Perhaps car makers would do well to heed this and start offering a full set of Landranger ordnance survey maps as an alternative option. It’s a thought.

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“Sorry Officer; It Won’t Happen Again.”

Yeah, right. Did you hear about the man whose wife ran away with a policeman? When he saw the flashing blue lights in his driving mirror he put his foot down because he thought they were bringing her back. Or how about the woman who assumed her speedo was deficient because she was at high altitude in the mountains?

“It never does that at home!”

Just two of the many excuses used to try and get away with a speeding offence.

No doubt any experienced traffic officer will be able to regale an audience with excuses, both clever and lame, that motorists use when caught going too fast. He probably will not reveal those where he was in the wrong – that’s another story.

The trouble with an excuse is that there is no excuse. Sure, you might get away with it if your passenger is about to give birth, but that’s about it; and anyway, there’s never a pregnant woman around when you need one (Curiously, there sometimes is when you don’t!). So, apart from matters of life or death your card will be marked, matey. Names will be taken. Heads will roll.

Modern cars have very accurate speedometers but they don’t measure how fast a vehicle is going; they work on how many times a wheel, or axle or driveshaft rotates. Then, by the power of electronics, they convert that to what a driver sees on his or her gauge. There is a variable. New tyres make the wheel ‘bigger’, if that makes sense, as does increasing the tyre pressure.

As a consequence the car will appear to travel further which will extrapolate to a greater speed. The same thing happens conversely. Thus, a small difference in wheel diameter gets exaggerated because the wheel is turning maybe six or seven times a second. Compounded, this can mean a difference of a few miles per hour. It’s a good idea to really learn the science of this. You can explain it to the boys in blue; they love a good lecture at the roadside. Can’t get enough of them.

Some people prefer to use the information provided by their navigation devices. These work by measuring the exact distance covered over time by GPS tracking. They can be affected by signal quality and, in some instances, struggle to factor in steep hills. Whichever system a driver uses there is always a margin of error.

The law requires that speedos must never show less than the actual speed and must never show more than 110% of actual speed. To counter this, manufacturers tend to calibrate their gauges high, thus helping to save drivers from themselves. This is also why the cops allow a margin of error although the same can’t be said of speed cameras which, as you know, have no soul.

Overall then, car speedos tend to read higher than sat-navs. It is not however the place of Motor Blogger to recommend one device over another. If you remain resolutely below the advertised speed limit you should be ok. If all else fails you could try slipping a fifty pound note on the ground and ask, disingenuously, if the officer had perchance dropped it. This is an especially good plan if you need a bed for the night.

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