Zero Tolerance Question
Discussion
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Just wondering: are we in a world of zero tolerance on speed cameras now or is there still a percentage error taken into account?
In my force the limits are set at 36 mph in a 30 mph,
46mph in a 40mph etc. I assume that this is to allow for error within speedometers and a degree of human error.
6 mph in a 30 is still 20% over the limit.
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Yeah, but I can WALK at 6mph .... the difference between 30mph and 36mph when you're in a modern, quiet car is barely noticeable ....
Yes it is ... and as a gov't advert correctly said a wee while ago, a car doing 33 mph will still be doing 13mph when one doing 30 has stopped, if they hit the brakes at the same time. From 36 mph it will be almost 20mph.
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Yes it is ... and as a gov't advert correctly said a wee while ago, a car doing 33 mph will still be doing 13mph when one doing 30 has stopped, if they hit the brakes at the same time. From 36 mph it will be almost 20mph.
Isn't that the advert that used the highway code figures John? which were written when the average family car was a ford anglia.
The advert with the car hitting the kid is utter rubbish you can even see that they altered the car to illustrate the point (locked fronts rotating rears?) The typical stoping distances for 30mph in the highway code is 23metres even SUVs stop in less distance than that.
No this is assuming the same car doing different speeds, different cars will obviously stop at different rates.
Works like this: When you slow down, your brakes convert the kinetic energy in the car into heat (mostly). Kinetic energy is proportional to speed squared.
Without going into formulae etc, the extra kinetic energy in any car going at 36 mph, when compared to the same car going at 30 mph, is equivalent to that in the same car going at 19.8 mph
ie when you bleed off the 30 mph worth of energy from the 36mph car, you still have 20mph worth of energy to get rid of before you stop.
Of course you might hit the brakes harder from the higher speed, and engine braking might help the faster car a little if you don't drop the clutch immediately. Air resistance will help a very small amount but won't be very significant at those speeds.
Works like this: When you slow down, your brakes convert the kinetic energy in the car into heat (mostly). Kinetic energy is proportional to speed squared.
Without going into formulae etc, the extra kinetic energy in any car going at 36 mph, when compared to the same car going at 30 mph, is equivalent to that in the same car going at 19.8 mph
ie when you bleed off the 30 mph worth of energy from the 36mph car, you still have 20mph worth of energy to get rid of before you stop.
Of course you might hit the brakes harder from the higher speed, and engine braking might help the faster car a little if you don't drop the clutch immediately. Air resistance will help a very small amount but won't be very significant at those speeds.
quote:
Yes it is ... and as a gov't advert correctly said a wee while ago, a car doing 33 mph will still be doing 13mph when one doing 30 has stopped, if they hit the brakes at the same time. From 36 mph it will be almost 20mph.
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quote:
Works like this: When you slow down, your brakes convert the kinetic energy in the car into heat (mostly). Kinetic energy is proportional to speed squared.
Without going into formulae etc, the extra kinetic energy in any car going at 36 mph, when compared to the same car going at 30 mph, is equivalent to that in the same car going at 19.8 mph
ie when you bleed off the 30 mph worth of energy from the 36mph car, you still have 20mph worth of energy to get rid of before you stop.
Yes this is true, but is to some extent irrelevant - assuming that you haven't just come off a track, your brakes will easily have enough power to give maximum braking to the disks
Assuming that you have good tires & are in a modern car, in the dry you should be able to sustain 1.1 g braking (from Evo mag this month)
If this is the case, then a car travelling at 33MPH can stop in 1.34 seconds or 9.88 metres (assuming deceleration of 11m per s per s)
The car travelling at 30MPH can stop in 1.22 seconds or 8.2 metres (these figures don't take into account reaction time)
When the 30MPH car has stopped, by my calculation the 33MPH car is doing about 3MPH
cheers,
Craig
If the driver is not looking where they are going. Good brakes or bad brakes, the kid gets it if you don't see him. People need to be taught to pay more attention when they're driving - that would IMO lower serious accident injuries more than anything. No more "Sorry, I didn't see him/you" type accidents.
I think 36mph in a 30 is a fair allowance.
I think 36mph in a 30 is a fair allowance.
Personally I would like to see a 5% per 10mph allowance on all speed limits. So at 30mph one would have to travel at less than an indicated 35mph but in a 70mph limit it should be an indicated 91mph.
I read a while ago that the camera limits on all London camera's in 40mph is 55mph.
Matt.
I read a while ago that the camera limits on all London camera's in 40mph is 55mph.
Matt.
Saw an advert the other week for a Merc, hinted at its sporting pedigree by being photographed on a driveway surrounded with armco, well maybe this isn't such a bad idea, keep cars and pedestrians apart by lining the edge of the road with armco 
then we can't mow them down on the pavement, and they can't run out in to the road!
And the drive to work will be like a trip around the Nurburgring
Bring on 150mph speed limits
then we can't mow them down on the pavement, and they can't run out in to the road! And the drive to work will be like a trip around the Nurburgring
Bring on 150mph speed limits
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Yeah true, you could well find that a modern 911 will stop quicker from 36 than a clapped out 2CV from 30. Or even 20
I don't recall the recent one about the car hitting the kid - the one I'm thinking of is 2-3 years old.
>> Edited by JohnL on Friday 7th June 14:32
The message should have been "watch out" rather than "slow down". I'd like to think that as you become aware of the dangers, you slow down accordingly. Simply telling me to slow down p!sses me off (I'm capable of assessing the dangers myself thank you very much) without making me significantly safer.
Fair enough the slower you go the less you hurt people when you run into them, but isn't it better not to hit them in the first place? I'd be very interested to see the ten or fifteen seconds beforehand showing the driver tuning the radio, talking on the phone, looking in shop windows or whatever it was they were doing when they should have been on the alert for hazards. If the driver had spotted the child standing in the middle of the road just one second earlier, that would have given roughly an extra 20 mph worth of braking distance. For example, what percentage of people driving down your average high street bother to look under parked cars to check there's nobody poised to leap out from behind them? What percentage have even thought about it?
Sadly, the "speed kills" message is fashionable and improving peoples driving is not.
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