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Autogrumble by 'GOM'

1. Revenue Cameras

The latest IAM press release concerns what are euphemistically referred to as "safety cameras", but ends with "At the same time, the survey shows that most drivers are unaware of the dangers of speeding, especially in built-up areas. Drivers were first told that an adult pedestrian hit by a car at 30 mph had a 20% of chance of being killed, and were then asked what they thought the chance of death was at 40 mph. Only a third (35%) gave the correct answer of 90%."

This sort of woolly thinking really makes me angry. Yes, OK, if you hit a pedestrian at 40mph you are more likely to kill him or her than if you were doing 30. BUT... your chances of killing an adult pedestrian by hitting him at 40mph are exactly the same whether you are in a 20mph limit or in a 60mph limit. There is a relationship between speed and damage, but not between the speed limit and damage. If we travelled at 0mph then the pedestrian's chances of survival would be greatly enhanced (reductio ad absurdum).

There's a tv ad that shows a car stopping from 30 mph just before someone dashes across the road, and then shows where the car would have stopped had it been doing 40mph. That's just applied mathematics! If retardation is constant then the stopping distance is proportional to the square of the initial speed. (Tip: to work out the Highway Code braking distance in feet square the speed in miles per hour and divide by 20.)

Our priority must be not to collide with the pedestrian in the first place, and that means driving at a safe speed appropriate to the type of road, weather and lighting conditions, visibility, parked vehicles and other obstructions, other road users, etc., etc. It's also in the pedestrian's interests not to collide with vehicles and to keep small children under control. The driver isn't always to blame - he just gets it!

Of course we must also obey the law but that's a separate issue. Speed limits are vaguely related to the type of road but often with quite glaring inconsistencies. You can be driving along a wide main road with good visibility and fenced fields on either side but with a 50mph limit. You then turn off into a narrow, winding country lane with houses here and there but no footpath, and the limit goes up to 60mph.

There is no correlation between the speed limit and safety. You cannot argue that it is safe to drive at 60 at one point along a road but that it is dangerous to exceed 30 two yards further along because you happen to have passed a lollypop with a "30" on it. What's more, I get the feeling that (a) speed limits are set 10mph lower than they need to be because many drivers will exceed them by up to 10mph, and (b) speed limits begin 200 yards before they need to because drivers take 200 yards to slow down after passing the sign. If you give the impression that that's what you expect then that's what you're gonna get!

John Maxwell summed it up nicely: "The thinking behind the speed limits on many roads simply isn't clear to many drivers, causing widespread frustration and disobedience. We need a national review so that speed limits are set at levels which are sensible, understandable and acceptable."

I'd go further. The problem is that with a few exceptions speed limits are fixed 24 x 7 x 52. Moreover they are increasingly being used to tell drivers what speed to drive at at the most congested times. 20mph outside a school when children are about is sensible but at most times of the day and night it is unnecessarily restrictive. The same applies to shopping centres. If there's a fixed speed limit it should be set at a speed that it sould always be unsafe to exceed. The Police have adequate powers to report drivers for a variety of offences even if they aren't exceeding the limit. Unfortunately the authorities are relying on dumb machines to collect fines instead of policing the streets properly.

If speed limits are reviewed then they should be taken out of the hands of local politicians. It is all too easy for councillors just to knock 10mph off the limit because "something has to be done", or because of pressure from a group of residents. There's a lot of hypocrisy here. Virtually all drivers are residents too, though not vice-versa, but it's usually a case of "not past my front gate". When cameras are put up it's usually the locals that get caught first. Residents can band together to lobby politicians: motorists and motorcyclists are never all together in one place. They can't put their point of view and they don't find out what's going on until it's too late.

As an aside I would add that if speed limits are reviewed then they should be metricated along with all other road signs, but that's for another day.

We must stop linking up speed limits for the sake of doing so. Speed limits should be applied where they are needed and relaxed when they can be. Rural 30 and 50 limits plastered all over the place are going to be treated with the contempt they deserve (not by IAM members of course).

So why do speed cameras come in for so much flack when it's the unreasonable speed limits that are the cause of the problem? If you obey the limit you don't get caught. But that's when you start getting frustrated. You're watching the speedometer all the time instead of the road. Your attention is wandering because you're having to chug along at an unnecessarily cautious speed. You're in a low gear to keep your speed down so you're using more fuel and creating more pollution.

It seems that the authorities have only one weapon in their armoury. Road safety must be achieved by the 'three Es' - Education, Engineering and Enforcement - not just enforcement of dumb speed limits with dumb technology.

Actually they do have more than one weapon - there's white paint, slalom courses and worst of all, the dreaded humps. I can feel the next 'autogrumble' coming on already!

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Last updated 28th November, 2009