Safe Speed Forums

The qualities listed here are laudable and it is right for drivers to consider soft skills like courtesy and responsibility. The truth is, though, that many people drive badly. The soft skills are altogether disappearing from our roads and being replaced by fear, greed, haste and intolerance, to everybody's detriment. That is why I am in favour of speed limit enforcement - for practical reasons. It just don't see how we can get at the worst offenders without limiting the easiest thing to measure - their speed. Almost everything else is subjective but speed is an easy to measure absolute that is a known factor in accident damage due to F=MA. Anything else will lead to endless quarrelling, so keep the rules simple so that everybody (including the boneheads) understands.

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I moved this post due to topic drift.

Safe Speed does not suggest removal or even raising of speed limits. There's nothing wrong with speed limits - they are an important part of our road safety system.

It's modern enforcement practice that's gone terribly wrong.

Boneheads or not we have to provide all road users with the best "accident avoidance toolkit" and lying about the dangers of exceeding a speed limit is making the toolkit worse, not better.

You mention F=MA (wrong equation, btw, I think you mean KE = 0.5mv^2), but the physics is irrelevant until the usual safety systems have failed. See:

http://www.safespeed.org.uk/consiracy.html and
http://www.safespeed.org.uk/tiger.html

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

Thanks Paul, I'll check out those web pages. F=MA is a basic law of Newtonian physics, upon which many others (including yours) depend.
Check out http://hyperphysics.phy-astr.gsu.edu/hbase/ke.html#c2

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I don't really think it's fair to say that the KE equation depends on Newton's second law of motion, neither do I think the most excellent hyperphysics site makes that specific "dependent" connection. But it's pretty "by the by" either way. While we're viewing the question academically, the question that needs answering is: In a universe where f=ma didn't apply, could ke= 0.5mv^2 still be true? Having looked at it for less than 5 minutes, I don't believe that there's any fundamental reason why not.

If anyone has not seen the Hyperphysics site before, I highly recommend it. I've been a regular visitor for years. Here's the usual entry point:

http://hyperphysics.phy-astr.gsu.edu/hbase/hph.html

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

I had an email as follows:

======================
KE = 1/2 m*(v squared) follows directly from F=ma, since energy = force *
distance.

s = ut + 1/2 a*(t squared), u = 0, so s = 0.5 a*t*t
v = u + at = a*t in this case
s = 0.5 * v * v / a
KE = ma * s = m a * 0.5 * v * v / a = 0.5 m * v * v, ie as above.
=====================

which a way of making the point that f=ma and the conservation of energy principle go together to make ke=0.5mv^2.

However, you can run the exact argument in reverse and "make" f=ma from ke=0.5mv^2.

So I'm none the wiser. Fortunately we live in a universe where the basic equations are known and predictable. As for which is more "basic", I suspect the answer is mainly a matter of definition.

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

and later...



I can live with that. I wanted to express the idea that ‘speed kills’ is a gross simplification of F=MA (or KE = 0.5mv^2 if you like), where the risk of death is vaguely related to the seriousness of the crash, which is itself vaguely related to the speed, and that speed is the only really easy attribute of driving to automatically determine and thus is a candidate for automatic enforcement.

I have a split opinion on automatic monitoring. It’s cheap, easy to implement, easy for drivers to understand, totally non-judgemental, can lower taxes by getting rid of coppers, is hard to dispute, has an effect, prevents ‘thumb in bum, mind in neutral’ driving styles, harms bad offenders more than light offenders, provides new risk indicators to insurers (to reduce my bill), etc. On the other hand, I’m getting fed up with this nanny state monitored society thing, with RFID, CCTV, ID cards, tax numbers, bar codes, and all the rest of it.

I'm not sure about this yet. For now, the best advice I can give is to obey the speed limit! What a novel idea.

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I don't agree with your relations there.

Risk of death (for a car driver) is related to about the 4th power of delta v (where delta v is the change in velocity during impact).

I can find no relationship between the risk of death and exceeding a speed limit that could reasonably be applied to normal responsible motorists. See:

http://www.safespeed.org.uk/proof.html

However reckless driving at highly inappropriate speeds carries a (comparatively) very high risk of death. (obvious example: stolen car at 120mph in town.)

Speed in excess of a speed limit is certainly easy to measure, but in the modern world we don't usually catch safety violations with such measurements. Mostly we're catching "normal responsible motorists" at safe and appropriate speeds. This is in part because the rules for speed camera placement are just plain wrong. See:

http://www.safespeed.org.uk/rules.html



Changing the behaviour of the nation of drivers does not come without side effects. In this case I believe that the side effects outweigh the potential benefits by at least ten to one. If we did succeed in getting everyone to obey the speed limit I believe we would see a huge rise in road death.

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

What's this idea about fuzzy enforcement? The number of instruments on roads and in cars is set to increase a hundred fold, as sensors and networks become dirt cheap. You are in the way of the automation steamroller. Why rage against scameras in the face of massive change that may well culminate in speed limited, routed, distance tariffed, drive-by-wireless transport systems? We have seen the congestion charge, and that is just the start.



Some motorists are in the habit of driving close to or higher than the maximum limit. What if motorists drive hard up against the middle of the road, sometimes straying into the oncoming traffic! What if all motorists constantly drive near to or over the drink limit! People treat the speed limits as if they were the minimum limit, not the maximum! What's the scoop on this - are they good or bad, hard or soft? Who would decide? Coppers – don’t make me laugh! If they are good in principle, perhaps they need raising in some areas due to better brakes, air bags etc. And maybe lowering near schools and houses.



Perhaps time (and statistics) will tell on that one, although I expect the introduction of speed governors before long, and the whole problem will be consigned to the dustbin of history where it belongs.

And remember - there's nothing wrong with speed limits - they are an important part of our road safety system. These words are incompatible with your disagreement about the risk of death when exceeding a speed limit. Perhaps speed limits are useful in other ways than reducing death, injury and damage, perhaps preventing wind noise or reducing engine wear!

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You make the same oversimplified assumption that too many others make, basingwerk, and that is that you reduce the skill of driving and accident avoidance to just pointing a vehicle in a particular direction and then maintaining it at the posted legal limit.

You suggest a world of fully automated road vehicles. Well, in much more regimented transport environments such as commercial aircraft and trains the technology to remove the pilot/driver has existed for years, yet it hasn't been done so as human skill is perceived, and in some areas actually valued, as the true safety valve in the avoidance of risk, accident and danger.

It's a sign of pure ignorance to argue otherwise.

Schemes intended to regulate traffic speed ignore the vital human contribution to road safety. Even the initial trials of speed limiters on a simulator demonstrated the problems in stark relief. It is to be hoed that the flaws become obvious in time to prevent the spread of "zombie safe" speed limiter technology. Let me tell you, I can't imagine anything much worse for road safety than 30 million drivers with their foot to the floor with their speed controlled by limiters. They will fail to slow down when necessary and many more will die.



The words are not incompatible - the question is: what purpose do speed limits serve? They serve three purposes very nicely:

1) They guide the inexperienced away from exceeding safe speeds by wild margins.

2) They provide valuable information to everyone else about expected hazard density.

3) They provide a ready means for the Police to prosecute those using speed dangerously or carelessly with nice simple evidence.

Speed limits are an excellent servant, but a terrible master. They must be kept in their place.

For most drivers most of the time choosing a safe speed according to the circumstances is hundreds of times more important than sticking to a speed limit. - And, unfortunately, we're telling drivers right now that their most important duty to road safety is to stick to the speed limit.

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

You most often see this on roads where the limit is set at a speed below which most people would choose to drive in the absence of limits.
On roads which have correctly set limits, most people spend an awful lot of time driving considerably below the limit - at whatever speed happens to be most appropriate for conditions at the time.
Because they have made a conscious decision to drive at the speed which they have judged, quite correctly, to be safe.
I cannot imagine what makes anybody think that these same people would, at a different time and place, deliberately choose to drive at a speed too high for conditions, and that it's only the speed limit which prevents them from doing so.
Conversely, the few who would choose to drive at dangerous speeds cannot be trusted to drive at a safe speed below the limit either. Whatever forces the latter drivers to stick to the limits anyway? These are the drivers who should be punished, or at least educated.
Having said that, if you have to have speed limits - for reasons other than for alerting drivers to hidden hazards, then the fairest way is to set them no lower than the 85th percentile speed - which is the speed most people would choose to drive at in the absence of limits. It's still not completely fair, because it's conceivable that a highly-skilled driver, in ideal conditions, could still go considerably faster in safety. And it's not a panacea for bad drivers either - they can still cause a lot of death and destruction at speeds way below the limit. That's why we need the kind of discretion which can only come from trained traffic officers - the kind of discretion which is totally lacking in scameras.
Why do we need, or want, to go faster?
Well, taking things to the extreme, if speed limits were set at walking pace, it would certainly stop most accidents, but if everybody took four to five hours to get to work in the morning and a similar time to get home in the evening, the country would go right down the tubes in a matter of days.
The faster we can travel - in relative safety - the more time we have for the important things. That's why mankind has always striven for more speed, almost from the year dot. Speed, probably more than most other factors, helped to bring about the civilisation and high standards of living we have today - pity about politics
Why do we need high-speed trains, when only about seven percent of people and goods travel by rail - a figure which is never going to change substantially?
Why, indeed, is the government seemingly hell-bent on spending billions in order to make trains do 200mph, and Ferraris 20mph?



There's actually no law which, by itself, says you can't. (or so I believe) We only drive on the left because it's customary to do so. But, despite it not being a specific offence not to do so, almost everybody sticks to the left almost all the time.

BTW your analogy to drink-driving was way off the mark. You need speed in order to move, you don't need alcohol. Police and emergency drivers are allowed to exceed the speed limit, but certainly not the drink limit.

Regards
Peter

Automation v humans? What happens if the auto-pilot do-dah fails and you do not have the skills to control the vehicle?

Skills need regular attention - "use 'em or lose 'em"

Beckham et al can certainly play footie - but they need to practice each day to maintain those skills. It is the same with any learned behaviour!






True too many see the speed limit as being the target speed, and will deliberately drive at speed above it if they can "get away with it!" But as we have said before there is speeding blip, camber, gradient, road surface polish which driver may not be aware of as speed "feels around 30mph" but could well be 34 mph and even then - speedo may not be as accurate as the Gatso setting. If OTT and definitely not a blip - I would pull and read riot act. Similarly if I saw motorist swerving or driving carelessly over white lane markings along the road - riot act reading would follow!

Scamera can only detect speed - it would not detect stray over lane marking unless we are talking of complete automation run by remote computer or tram lines here.

By the way - think we use left because horse/cart and farmer ploughing his fields tended to use the left.



Know we have a "Magic Eye" being tested at Alsager - which allegedly can detect drink, drugs and fatigue via eye movement and co-ordination - but that technology is in infancy and may not even come into being.

But in meantime - scamera cannot detect this and current technology and less trafpols operating in certain areas of the country is leading to too many "chancers" That is one major argument against over-relaince on the camera to detect crimes on the road. Scameras only detect speeders!




Yes - we know! Speed limits to some are the target speed and they will drive at that speed even if that speed is too fast for road conditions. Again - something that a good trafpol would pick up on and a scamera will not. Again - they would get my lecture - but not necessarily an NOIP!



Why do we make you laugh? Insinuating we are not earning our crust are we?

Drivers do not have an easy time in our patch at all - do not kid yourself!
We prosecute when justified!



Yes. Agreed. Some speed limits are set intolerably and misleadingly lower than they should be. And some are set far too high! We can all name roads in our areas to which this would apply! Some areas have indeed introduced 20mph in residentials and past schools. The problem with the schools is that limit should be variable - ie lowered at peak danger times, and set at normal 30mph at other times of the day. Naturally, this would need signage and big information campaign to make it work. Numpties, of course, wil this hammering into them by force!

[quote ="basingwerk"]
And remember - there's nothing wrong with speed limits - they are an important part of our road safety system. These words are incompatible with your disagreement about the risk of death when exceeding a speed limit. Perhaps speed limits are useful in other ways than reducing death, injury and damage, perhaps preventing wind noise or reducing engine wear![/quote]

No, there is nothing wrong with a (preferably sensible ) speed limit. Slight blips over are one thing and deliberate disregard is another. Drive applying COAST at all times - and you will find that you will be driving at safest speed - which you will find is very close to the posted limit anyway! (well it works for me, the Mad Cats, our family nerd, etc.)

Wind noise and engine wear? Driving at slower speeds helps the old crocks - but again people are lulled into thinking their modern cars are safer than they actually are because they are quiet and powerful! And many do not understand the mechanics and thus the feel of their cars!

Thanks, r11co, I'm aware of that. But speed is the only thing you can incontrovertibly measure easily with a road side instrument, so it is bound to be the first phase of technology - other things might follow, like bar codes, RFID, CCTV, and even instruments to allow inspectors to stop your car remotely with a button push!



Fair point. Pilots could tell you about how they take off, switch on autopilot and just monitor the plane for hours, then land again. The planes have automatic navigation, RFID, blackboxes, collision avoidance etc. and the whole trip is monitored by an army of ground controllers - if you agree that this is what car drivers have to look forward to, this would confirm what I say. A similar situation is coming about for trains. I believe there is a driverless subway planned in Nanjing, and there is a subway with a driver without contols somewhere is the US. A guy sits at the front to reassure the passengers, but he can't do anything! Maybe that's just an anecdote, it seems too weird to be true. As for safety - how are most accidents caused, r11co - human error or system failure (brakes, steering, lights, potholes etc)? What's your guess?



You've shot me down in flames ... arghhh.

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We don't HAVE to introduce new technology simply because it exists! So far it seems that we've introduced speed measurement technology simply because it is the only thing that can be measured, and the results have been nothing short of disastrous. It has worsened our road safety performance, subjected hundreds of thousands of motorists to unnecessary and unwarranted fines, and undermined regard for law enforcement. What's next then?


Aircraft are fundamentally different, in that once they have left the ground they deal with a far more predictable environment, where nearly every hazard can be automatically acquired and dealt with. As such the task of flying a plane is not actually very demanding on the pilot, so it makes sense to assign this fairly mundane task to a computer which doesn't get bored.

This is a million miles away from motoring, where hazards appear every few seconds, each of which has it's own unique characteristics that require individual analysis and decision making.

Flying a plane automatically is like having an automatic feed on a sawbench which is cutting planks of a given thickness. Driving a car automatically would be like asking the same machine to make those planks into a dining room table and chairs!

r11co,

I just learned that the London Docklands light railway has no driver. I was behind the times with my dire prediations, and it has already happened

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More of the same, I’m afraid. Road managers (coppers, the judiciary, local authorities, the government etc.) want more data on traffic usage, speed, density and so, and on accident rates, survival rates and so on. There’s a whole industry devoted to the collection of this data, and measurement and control technology is the tool of choice for the raw data collection because it is absolute, not subject to human interpretation.


Every case seems fundamentally different! Can you be sure that you don't actually want cars to be fundamentally different because you like them and want to retain your control? On the other hand, it is easier to measure and control a plane for the reasons you give, and that explains why that was done first.



Yes, we can agree on that - dining room table and chairs are made by automatic machines nowadays.


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There are trade-offs here - if the auto-pilot do-dah fails and you do not have the skills to control the vehicle, it’s chop-chop-charlie, isn’t it! One reason not to put it in. On the other hand, robust systems might have contingency processes.



Sorry officer .

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Heheheh. Those driverless trains scared the hell out of my aunt the first time I took her on the DLR. Don't think there'll be universal support for fully automated transport systems for a while yet.

Besides, the only regular hazards are those within the system itself, and presumably these were either designed out or are under automatic control as well (other trains for example), hence there's not much for a human operator to do. Even on a normal train the driver doesn't have to steer the thing, but in case some idiot runs across the tracks at least there is still a driver who can slam the anchors on. I have no idea what, if anything, would apply the brakes on the DLR if someone ran in front of a train. Fortunately as the DLR is an elevated railway, at least all the bits I've been on are elevated, I doubt there's much chance of this happening (the hazard has been designed out).

So could we automate the roads in the same way? I just can't see how that can be done. Hazards come and go too quickly and unpredictably. There's no reason to suppose that the junction you passed in perfect safety yesterday will be hazard free today, so there's no substitue for an alert human driver. Sure, if every vehicle was under some form of central control then planks who don't look can't pull out without warning anymore, but what about pedestrians, cyclists, horse riders, loose animals etc? Probably bikers too, unless the computers can act in such a way that the bike doesn't become unstable. They are all elements that are prone to acting unpredictably and can never be brought under a central control. Nothing short of total segregation of road traffic would do, which is practically impossible.

Every inch of road would have to be fenced off except areas designated for people to get in and out of vehicles, new networks would have to be constructed for cyclists and horse riders, and possibly bikers. Even then, unpredictable hazards won't have all gone away. Ever see the episode of Police Camera Action where a patrol had to stop the traffic and chase a swan off the M25? I seem to remember them saying that it happens several times a year, possibly because swans are thick and mistake wide roads for rivers. Whatever the cause, the idea of running into a bird the size of a swan at 70mph in a car where software is running the show doesn't excite me at all, so we'd have to enclose all the roads as well. Then there's the risk, admittedly very low risk, of other forms of transport entering the system without warning. A private jet had a mechanical failure and went off the runway at a small airport by the A30 recently, and nearly ended up on the road. Say it had gone an extra 30 yards and all the traffic was on autopilot. Not a pleasant thought. Sure that sort of thing is pretty rare, but it could happen again tomorrow and I for one would prefer to able to take action myself than sit there hoping like hell that the computer has noticed it. What about burst water mains? They occur without warning and the chaos they cause is bad enough as it is. Can we trust computers to take account of the sudden change in conditions and react appropriately as human drivers would instictively do?

But just for the sake of argument, let's say we could somehow remove all these hazards. There is still a human element in the system that could potentially produce something unpredicatable, and it is fundamentally impossible to do anything about it. Humans would have written the software that the whole bloody thing relies upon! Even assuming that it's not nearly as crash prone as my copy of Windows 98 (obvious gibe I know, but too hard to resist) can we safely assume that such a massively complex system would be absolutely bug free? That just isn't going to happen unless we first perfect humanity. And of course, if humans became that good we wouldn't need the whole road network under computer control anyway.

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I am talking hypothetically here, but I would guess that any control process would be the opposite of central control – it would work on the principle of localised control that is as diversified as possible, i.e. to the cars. That is how some networks work, e.g. the Internet – no central control at all.



Yes, and to ensure complete safety perhaps we should go back to the days when a man walked in front with a flag, just in case.



98 was a bad release, use 2000, which has a better kernel. No, I don’t think any system could be absolutely bug free. Just like the human system we have now, there would be errors and accidents. But one thing about software is that it can be fixed, and when it is, it stays fixed. Complex systems are built up using incremental improvement processes. For example, you can log into the Internet through an RF connection, access a web page in Vancouver and put in an order for a Satellite image. Mission controllers, who will prepare an upload for a pass, will process the order. The pass will happen; a radar image of your target would be taken and downloaded to a ground system in Ottawa, processed, and emailed to back to you. This is a real scenario, and it takes millions upon millions of lines of code to enact, but the system is up and running (has been since 1995) although it is rather costly at around $100K per picture. And no, it is not safety critical. The point is, though, that such systems of unimaginably large complexity are becoming commonplace, so who knows what the state of driving will be in 10 or 20 years? I am fairly sure that there will be much more monitoring than there is today, and maybe some automation, and control. Whether that will ever lead to full automation, I could not say, but if it did, the automatic system would have to have clear safety advantages over the manual driving system. In any case, such a transition would be gradual at first - expect more instrumentation (cameras and RF detectors, satellite locators, GPS, that sort of thing) and see where it leads.

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I remember seeing a trial of an automated road system on Top Gear I think it was a few years ago. Think the trial was in Germany.
They had a bunch of cars in a special lane linked together by radar travelling at 70 odd mph just a few inches from each other. Computers controlled the power and brakes. Cars could join and leave the train at junctions, the remaining cars would close up and the train continue, all without stopping I add.
The idea is terrifying, what if one computer failed? What if one car suffered a mechanical failure? What if....well I'm sure you can think of any number of scenarios that would result in a horrific pileup!
Nightmare