seen this?

Erm, although technically still under motorway regulations, a roundabout with traffic lights isn't really a motorway, is it? - 60mph on a roundabout with lights is just plain stupid - certainly more stupid than eeek! mph on the motorway.

Reply to
SteveH
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Daft question, but I don't really know the M25... are there actually roundabouts and traffic lights on the motorway itself ?

Reply to
Lordy

No. They're at the end of the slip roads.

Reply to
SteveH

I've seen speeds this high all over the place and reckon it is normal on open junctions like on motorways or along dual carriageways even with lights - the lights on most motorway roundabouts allow for about 100 or so. It's certainly not unusual to see roundabouts where people are easily as fast as 60, but sometimes the road curves enough to make that a bit too fast. But that's nothing to do with the traffic lights, that's to do with how fast your car can corner and feel safe.

I often slow down on roundabouts anyway, when the corners are fairly tight, trucks often slop diesel onto the road so you have a fair chance of finding the tyres have no grip for a patch, which could be embarassing on most motorway junctions.

Reply to
antispam

LOL!!!!! no no no, the motorway junctions are slip roads and they have roundabouts at the end of them or they turn into another motorway and given the size of these roundabouts it's easy to go round at full pelt

Reply to
nooneyouveeverheardof

It may well be easy to take them at these kinds of speeds, but the safety of doing it is definitely questionable.

Reply to
SteveH

Me thinks swift removal of sexual relations triggered the posting of this auction on ebay.

So why don't we benefit from it and have a good laugh. Get the bids in ;-)

Matt

Reply to
**-**

Ah yes, saw that in the paper yesterday with a photo of the road (well it could have been the road, it was The Sun afterall). If the pictured road was the road he was caught on there was houses down the side. Speed testing a car on a deserted motorway at night is one thing, but in a resedentail area at night, there could have easily been kids about, a drunkard wondering about across the road etc etc. IMHO he should be locked away and banned for as long as possible. His defence was that he was driving a powerful car that he wasnt used too. FFS a Golf VR6 isnt *that* powerful, and WTF is the speedo there for? Wanker!

In fact, theres a photo of the road on this page:

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Reply to
Carl Gibbs

It's not as if anyone was hurt, now is it. This on the other hand ended differently:

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I wonder if charges will be forthcoming for the driver?

Reply to
Depresion

Thats not the point, it was totally reckless and shows a complete lack of intelligence. What would have happened if he had hit a kid/car/house at

116mph? At the very least he should have a long term ban to stop him doing anything like that again. Probably get a £50 and 6 points though(!)
Reply to
Carl Gibbs

Woulda made a right mess of an otherwise tidy lookin Golf....

Reply to
Dan405

That's what I thought. So why is he going on about them being on a motorway, I assume just to deflect attention away from the fact that going through a junction at high speed is not acceptable ?

Reply to
Lordy

So what speed do *you* accept we can go through a junction at?

Be specific. "High" isn't a speed, "high" is relative. 3mph is running with scissors. Maybe if you can get it right, we can change the national limit.

Reply to
antispam

It certainly isn't 60mph, lets put it that way.

High could well be taken to mean any speed that isn't appropriate to the circumstances - 60mph is definitely what I'd consider a 'high' speed when around light-controlled junctions and roundabouts. Just because the limit is 60mph, doesn't mean it's safe to do it.

Reply to
SteveH

JAIL ?!?!?

Whilst I totally agree that he is clearly STUPID, and that was a LUDICROUS speed to be travelling on a 40mph road, he CERTAINLY doesn't deserve jail !

He completely deserves to get a right royal kicking from the courts, but to send him to jail is excessive in the extreme. I fail to see how a custodial sentence can be justified for a victimless crime, that didn't cause one jot of harm.

Reply to
Nom

Exactly. Now, if he had crashed at that speed, and killed two people, then he should rightly be sent to jail.

But he didn't. In fact, NOTHING WHATSOEVER happened as a consequence of his crime.

How is it fair to send someone to jail, if they break a law, but cause nothing whatsoever to happen as a result ?

For obvious reasons, the punishment should fit the consequences of the crime !

I would hope not. Assuming the copper had his Lights and Sirens on, then she shouldn't have been in the road ! To be in the path of the car, means she must have been crossing without looking - hardly the fault of the driver ! For all we know, that Police driver was on his way to stop a murder.

Reply to
Nom

It's EXACTLY the point.

He performed an act of 100% STUPIDITY, with no consequences. Sending to him to jail for it, is madness.

The first time you beat someone up in the street, you escape jail. Clearly that's a much worse crime.

They would have totally died. In which case, the consequences of his actions would have been very different, and he should rightly be sent to jail.

Yep. Lots of bans and fines and stuff.

Reply to
Nom

It's simple physics. Travelling at twice the speed, it takes twice as long (in seconds) to stop, but your average speed over that time is twice as high, so the overall distance is 4 times as long.

This only take into account the actual braking part of the stopping, not reaction distance, and it assumes that the decelleration is linear, but that's a pretty good assumption.

Reply to
Andrew Kirby

Lengthy post, but nothing challenging.

Ok, take a piece of paper, pencil and ruler. Draw a vertical line on the left of the page, a horizontal line on the bottom, and turn it into a rectangle with two more lines at right and top.

The length of the line on the left is your speed, and the length of the line along the bottom is the time involved. The area of the rectangle is the distance you travel.

E.g. 40 meters per second, about 90 mph, represented by 40 cms height and ten seconds along the bottom, divide up the rectangle into vertical strips once cm (or one second) wide, and 40 m/s long. Each strip is 40 meters per second, in one second, making forty meters travelled (the definition of speed is distance per unit time.) The whole rectangle's area is the distance travelled in ten seconds, ten times 40 makes 400 meters.

Now, if you brake from 40 m/s in ten seconds, that's a fairly reasonable time and a bit under half the force of gravity pulling you forward so not possible without pretty sound brakes and tyres in good conditions.

The speed now goes down with time, so you draw a diagonal line from the 40 m/s initial speed to 0 m/s on the right, after ten seconds. Instead of a rectangle you now have a triangle. The area of the triangle is obviously about half the area of the rectangle, and in those ten seconds you don't travel 400 meters, you travel a total of about 200 instead.

Now consider the right hand part of the triangle, from five to ten seconds rather than 0 to five. The speed at the start of this section is half what it originally was, e.g. 20 m/s or about 40 - 50 mph, half the 90 mph you have on the left.

The deceleration is the same in each half, i.e. the brakes work equally well at

90 as at 50 and 30 and 10 mph, so in five seconds, they took 20 m/s off whatever speed you started with, 40 down to 20, 30 down to 10, and 20 down to 0 wherever you start your timer.

The distance travelled / area of the triangle in the right hand five seconds, though is obviously around a third of the area of the triangle on the left hand five seconds of the overall braking period. It is a quarter of the total compared with three quarters of the total.

In simple terms, if you double the initial speed, you are doubling the braking time, and since the distance depends on initial speed and total time it rises by twice times twice, or four times.

Comparing theory to practice, well, it's likely that the braking force varies to some extent with speed or time and therefore the diagonal line won't be perfectly straight. However, you have to have some pretty distorted shapes before it makes a significant difference to the area under that diagonal line, no?

Another thing to consider while looking at triangles on paper, is what happens when the distance you travel is fixed, e.g. the car ahead is stopped and you can only brake until you hit it. If you are travelling at 20 m/s, you travel for 5 seconds and cover a distance of 50 meters. This is the area of the right hand half of the triangle. Now move the ruler to cover an piece of the same area starting from the left hand side. It's not five seconds wide, it's not even two seconds wide, it's actually about a second and a third wide for the same area, and the speed at the end of that period is not much less than the 40 m/s starting speed.

What this means, in numbers, if you start off travelling at 40 m/s and emergency brake for 50 yards, you hit the object at the end of your 50 meters a little over one second later and still travelling at 33 m/s (which is about 75 mph). You shed 15 mph during your braking distance.

If you start off travelling at 20 m/s and emergency brake for 50 yards, you don't quite hit the object or you do so at a speed barely above zero, around five seconds after you started to brake. You shed 45 mph during your braking distance.

Therefore, for a given emergency braking distance, your terminal velocity is considerably higher than simply the extra speed you happened to be travelling at. Every extra mph adds a strip to the left of the triangle, where it has somewhat more effect on your braking distances and terminal velocity than the previous mph you added, which becomes extremely relevant in towns where it is not unusual to find your braking distance is fixed by whatever ran into the road and isn't something you can trade off, so that what seems like a few percent more speed, can quickly double your terminal velocity and make an enormous difference to whether the dog / child / etc bounces harmlessly, bounces with injuries, or has almost no chance of survival.

This is quite simple physics, really, and can be done by counting squares on graph paper rather than needing excel to calculate your speeds / times / distances (although I admit did it in my head and I'd use excel for more complex stuff because I dunno where my ruler is.) And also, theory matches practice very closely indeed, real world variations due to driver skill / tyre friction / road quality won't influence the relative comparisons of the times, distances and speeds you are basically using. It's obviously true an F1 car can stop in a shorter distance than a Lada, but the same F1 car at 40 m/s will take four times as far to stop as it does from 20 m/s, within a few percent even in the real world. And the Lada will take four times as long to stop from double the speed using the same Lada. Also, the differences from F1 to Lada are surprisingly un-huge when it comes to braking, even though they're huge when it comes to acceleration.

Reply to
antispam

So if you fire a gun in public, but no one gets hurt is that ok too?

You need to look up the law on driving offences. having read the leaflet you get after an accident (works van, oooops) the penalty you get is based on your actions, not the consequences. So someone doing 28mph past a school and knocking over a kid that consequnetly dies may get 3 points and a fine for driving without due care and attention (unlikely situation i know). However doing 116mph in a 40mph resedential area is totally stupid and shows complete lack of sense/understanding of driving a motor car and deserves to be punished. OK jail might be a bit harsh, but a long term ban (i mean in terms of years) is very appropriate IMHO. And TBH a few months locked up wouldnt hurt either.

Reply to
Carl Gibbs

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