Somethng Different

[Gods_gift]

Dont forget that as stated speedo sync is initially calculated by a set tyre/wheel size and final drive ratio. When you alter wheels and tyre sizes this has an effect but also the air pressure in the tyre caused by outside conditions has a big effect. In motorsport they us a gas mix to make this more predictable hence why cold tyres effect overall speed as well as grip.

[firemac]

Hoovie's point is a good one. You could have near-accurate speedos if you're prepared to pay for them.However, such accuracy would require a network of external monitors or accurate in-car radar or low power laser systems. From my point of view though I don't see why it should be important whether you're doing 60 mph or 61 mph. If you're calculating re-entry speed for a space vehicle that will turn into an airborne BBQ if you get it the slightest bit wrong then, yes, accuracy is paramount; not on the A34 however.

As far as I'm aware, the construction & use statutes require that speedos must not under-read but that they can overstate speed by a reasonable amount which is generally accepted to be up to 10%. GPS is very accurate but only on level ground- gradients create inaccuracy which increases with the scale of the gradient.

[anchorman]

Agree with trucks not overtaking. I have followed many single cell creatures that will take several miles to overtake at o.o5 mph faster than the next. If WE held them in that way the single cell creature would want to pull us out of the driving seat if it could do so and stand on it's back legs at the same time. Cars should still be allowed in lane 1 of a dual carriageway though.

Agree even more with trucks off the road altogether especially for qualifying long distance or bulk loads. If a truck wishes to drive through Switzerland it has to board a train.

Speedos have to have any inaccuracy biased to high and cannot compensate for tyre wear unless it is an optical device that is pointed at the road surface.

Sorry for the £3 a litre. Should have been £4 but the transport system needs to be frequent, good quality and cheap. It should be so good that we should be really stuck not to use it. I drive down our narrow main street and there are cars littered everywhere by dolts who are too lazy to walk and have no regard for pedestrians. Anybody parking on a footpath should be tasered - twice. Any vehicle with an exhaust 1% louder or more than design should be tasered in triplicate - twice.

[firemac]

Agree even more with trucks off the road altogether especially for qualifying long distance or bulk loads. If a truck wishes to drive through Switzerland it has to board a train.

Sorry for the £3 a litre. Should have been £4 but the transport system needs to be frequent, good quality and cheap. It should be so good that we should be really stuck not to use it. I drive down our narrow main street and there are cars littered everywhere by dolts who are too lazy to walk and have no regard for pedestrians. Anybody parking on a footpath should be tasered - twice. Any vehicle with an exhaust 1% louder or more than design should be tasered in triplicate - twice.

Switzerland's not a good example. The only reason for training trucks is so that they don't wake the population up! Switzerland is the most boring place on earth IMHO. Any self-respecting trucker wouldn't be caught dead in the place.

Don, you've really got to work on that liberal streak of yours; it's turning you into a big softie. :D

[anchorman]

I know, I normally baseball bat after tasering!

[crofter]

Tell me Don and Jim have you always had this hatred of trucks and the most regulated,data recorded drivers on the road.

Come on you truckers lets hear from you.

Del (one time trucker)

[Gods_gift]

Why do they overtake on hills?

[firemac]

Tell me Don and Jim have you always had this hatred of trucks and the most regulated,data recorded drivers on the road.

Come on you truckers lets hear from you.

Del (one time trucker)

Hi Del,

I thoroughly detest the crawling, Yorkie-munching crowd of b*st*rds!! Just kidding.

Seriously though, where did I say anything hateful about truckers? The Swiss, yes; they inhabit the most boring, regimented, navel-gazing society on earth.

But truckers are generally OK. It's not their fault that we binned the railways back in the 60's resulting in all the road freight we suffer now. It is enlightening at times on the M6, at the right time of day/night, where you can get lines of wagons that seem to go on for miles; shows just how much road space is taken up by freight that could be on rail.

[crofter]

Why do they overtake on hills?

I think Don has the measure of the drivers,I won't consider them to be the average trucker, of the drivers who sit alongside each other for what seems like miles. A bit of common sense from either of them would work for the benefit of all.

What happened to the old notion the the vehicle in front has precedence.

Come on, you must admit, there is a mind set amongst some drivers that nothing,but nothing, should impede their progress and the only speed is the maximum one,or the one to which they think that they themselves must maintain regardless of any other criteria.

Anyone remember the old saying "Better to arrive a little late in this world than early in the next one"

Del

[Gods_gift]

Why do they overtake on hills?

I think Don has the measure of the drivers,I won't consider them to be the average trucker, of the drivers who sit alongside each other for what seems like miles. A bit of common sense from either of them would work for the benefit of all.

What happened to the old notion the the vehicle in front has precedence.

Come on, you must admit, there is a mind set amongst some drivers that nothing,but nothing, should impede their progress and the only speed is the maximum one,or the one to which they think that they themselves must maintain regardless of any other criteria.

Anyone remember the old saying "Better to arrive a little late in this world than early in the next one"

Del

It's is just ignorance on a dual carriageway uphill section for a lorry to try an overtaking manoeuvre. Anyone who travels on the A1 must see this every day.

[crofter]

To try and overtake on a hill,or anywhere else,when you do not have enough grunt not only shows ignorance of the capabilities of your trunk but basic bad driving practice.

Good manners and consideration for other drivers was the norm when i started driving goods vehicles,but I think drivers were more courteous then.Simple things like giving way to climbing traffic even tho' the obstruction was on their side of the road.

I suppose that the pressures are greater now on everyone and a me,me attitude is growing as well as a sense of agrievement over what was once thought of as trivial.

Del

PS suprised no one has pulled me up on the spelling of the title.

[anchorman]

Don't hate truckers across the board, only some with the "mightier than thou" attitude. Some are real nights of the road but some are just ignorant. Most of them drive Scanias and Volvo's and the like but make out they are in charge of a herd of wild bison. The smallest woman could drive one and probably better in many cases. I used to drive old Fodens which were hard to drive but most of these modern things are like saloon cars but easier to drive if anything. The act of taking miles to overtake just says it all. Like the cretins I tell daily to take their wet shoes off train seats and the brain dead with big bore exhausts, just no regard for anybody else, only them.

[redlew]

PS suprised no one has pulled me up on the spelling of the title.

Noone wants to csat the first stone.

[Joylove]

GPS is very accurate but only on level ground- gradients create inaccuracy which increases with the scale of the gradient.

Sorry this part is not correct. With a five satellite or more fix, you get full 3D tracking including the correct speed.

And trucks overtake on hills because the different weights of the empty trucks allow them to maintain momentum over the heavy trucks and to nose ahead.

[firemac]

GPS is very accurate but only on level ground- gradients create inaccuracy which increases with the scale of the gradient.

Sorry this part is not correct. With a five satellite or more fix, you get full 3D tracking including the correct speed.

That's interesting, Bob. I'm certainly no expert but presumably that degree of satellite acquisition is not the norm with most "domestic" sat navs. I can understand that military applications would undoubtedly need such accuracy however.

[crofter]

Do you know,I think there will soon be more traffic up there than down here.!!!

I assume that the are all going the same way.

Del

[Joylove]

GPS is very accurate but only on level ground- gradients create inaccuracy which increases with the scale of the gradient.

Sorry this part is not correct. With a five satellite or more fix, you get full 3D tracking including the correct speed.

That's interesting, Bob. I'm certainly no expert but presumably that degree of satellite acquisition is not the norm with most "domestic" sat navs. I can understand that military applications would undoubtedly need such accuracy however.

The military and civilian system is identical, except the military purposely injects clock jitter into the civilian system to reduce the accuracy from 1m to 10m. GPS manufacturers have gained some of this intentional positioning error back with differential receivers and having over 30k correlators rather than the original 12, giving somewhat better performance after acquisition than originally envisioned with a clear sky view and in built up areas.

I looked into this a little while ago, and if memory serves the velocity of the receiver in 3 dimensions (5+satellite) is calculated about 20 times a second; even if the majority of satnav speed displays only updated every few seconds the data is there to be used.

[anchorman]

My satnav often says it is connected to 10 satellites and it is a right old one like me!

[Davrav]

My 'mapnav' often tells me I'm going too fast...................

[crofter]

My 'mapnav' often tells me I'm going too fast...................

:argue:

Some maps take a lot of reading,you know,its all right for you,you only have to stay on the road.

I read somewhere once that someone produced "upside down maps" as the navs struggled to read normal ones if heading south as their finger had to travel the other way to which car was travelling(I think)

Del