When did 30mph become too fast?

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“may” and “might”. Other cars ‘may’ be as happy at 20 as they are at 30 in the same gear. So they would need FEWER power strokes over the distance travelled, thus much LESS pollution. They ‘may’ cancel each other out, or overall pollution ‘may’ be higher, or it ‘may’ be lower.
This could be funny.
 
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The 20mph limits were introduced to stop people driving at 40 in a 30mph zone because as we all know if circumstances allow everyone ( ok not everyone ) adds 10mph to the limit.
The local authority have recently slapped a carpet 20mph limit on a town near me as a lot of elderly pedestrians were unfortunately stepping out in front of moving vehicles. The 20mph limit has been in place for about 2 years now and there has not been one prosecution for excess speed in this time. When the limit was 30mph the "camera van" and traffic cops enforced the limit accordingly but at 20mph the speed detection equipment is not authorised to be used for prosecution unless the home office guidelines have been altered recently.
Anyway, most of the 20 limits don't last for a great distance, so slow down and relax for a couple of minutes and have a nice day.
I'm now off to the pub to watch the footy and I will not be exceeding any speed limits.
Anyway, most of the 20 limits don't last for a great distance, so slow down and relax for a couple of minutes and have a nice day.:):):) Spot on. No more needs to be said.
 
“may” and “might”. Other cars ‘may’ be as happy at 20 as they are at 30 in the same gear. So they would need FEWER power strokes over the distance travelled, thus much LESS pollution. They ‘may’ cancel each other out, or overall pollution ‘may’ be higher, or it ‘may’ be lower.
I'm not saying it's impossible , but I am hard pressed to think of any car I've had which would trickle along happily in 4th gear at 20 mph , whereas all were happy at 30mph without labouring the engine .

Oh , BTW , if a car is in the same gear at 20mph and 30mph then the number of power strokes over any given distance remains exactly the same .
 
Oh , BTW , if a car is in the same gear at 20mph and 30mph then the number of power strokes over any given distance remains exactly the same .
OK, you conned me into that one. I should have written that less fuel will be called for and burnt, thus less pollution.
 
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The worrying thing is it seems we have amateurs (local councillors) making decisions on something they know nothing about. Someone posted a link to the article which highlighted accident rates going up when 20MPH limits were enforced and that this was a national trend. Then there was guidance from government that slowing down traffic really does increase pollution. So why are local councils ignoring this information and still doing it. I don't want our roads managed by amateurs.
 
The worrying thing is it seems we have amateurs (local councillors) making decisions on something they know nothing about. Someone posted a link to the article which highlighted accident rates going up when 20MPH limits were enforced and that this was a national trend. Then there was guidance from government that slowing down traffic really does increase pollution. So why are local councils ignoring this information and still doing it. I don't want our roads managed by amateurs.
The problem with such reports is that they demonstrate how accident figures have increased on 20mph roads whilst falling on other roads. Think about it, of course they have. Why? Because we’re getting more and more 20mph roads. The more roads, the more opportunities for accidents. A council area that starts without any 20 mph roads starts with an accident rate of zero on them. One accident results in an infinite percentage increase in accidents. If they quadruple the miles of 20mph limit roads the following year and have one more accident, that shows on the statistics as a 100% increase. Meanwhile the 30mph roads are getting less and may even have one less accident, but that shows as improved accident statistics for that type of road. But hey, that’s boring for the media so they all mislead us by shouting about how the 20mph roads are leading to more accidents. Real statistics tell a more accurate story.
https://www.rospa.com/rospaweb/docs/advice-services/road-safety/drivers/20-mph-zone-factsheet.pdf
 
“may” and “might”. Other cars ‘may’ be as happy at 20 as they are at 30 in the same gear. So they would need FEWER power strokes over the distance travelled, thus much LESS pollution. They ‘may’ cancel each other out, or overall pollution ‘may’ be higher, or it ‘may’ be lower.
Measured emission levels are consistently higher in 20mph zones than elsewhere.
 
Perhaps simplistic , but it seems obvious to me that , even when , in the best case scenario , one is travelling at constant speed on level ground with minimal throttle applied , a vehicle travelling in a lower gear ( and most vehicles WILL be able to be in a higher gear at 30 than at 20 ) will be taking in and burning more fuel/air charges per unit distance travelled , hence producing proportionally more emissions .

Add in stopping/starting , changes in speed , recourse to even lower gears and it just gets worse .
 
Perhaps simplistic , but it seems obvious to me that , even when , in the best case scenario , one is travelling at constant speed on level ground with minimal throttle applied , a vehicle travelling in a lower gear ( and most vehicles WILL be able to be in a higher gear at 30 than at 20 ) will be taking in and burning more fuel/air charges per unit distance travelled , hence producing proportionally more emissions .

Add in stopping/starting , changes in speed , recourse to even lower gears and it just gets worse .
I would argue that there’s less need to change speed when driving through a residential area at 20 than at 30. More hazards can be negotiated at 20 because there’s less need to significantly adjust speed. The stopping/starting, changing speed and using lower gears is mostly a factor of poor driving skills, especially observation and thinking ahead. Perhaps it’s drivers who need educating rather than specific speed limits imposed - in my dreams!
 
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Roads with lower speed limits are by definition the roads with more hazards (including junctions) and thus more need to change speed regularly. So of course roads with 40 limits are going to produce less pollution. But that doesn’t mean that a 20 or 30 limit road would produce less pollution if the limit was increased to 40. In fact I would suggest that the opposite would be true because there would be greater changes in speed with extra acceleration to return to 40 after every hazard.
 
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Roads with lower speed limits are by definition the roads with more hazards (including junctions) and thus more need to change speed regularly. So of course roads with 40 limits are going to produce less pollution. But that doesn’t mean that a 20 or 30 limit road would produce less pollution if the limit was increased to 40. In fact I would suggest that the opposite would be true because there would be greater changes in speed with extra acceleration to return to 40 after every hazard.
While I accept your contention in general , in present day political climate , some roads may have lower speed limits purely to gain votes or score points against opposition...
 
Anyway, most of the 20 limits don't last for a great distance, so slow down and relax for a couple of minutes and have a nice day.:):):) Spot on. No more needs to be said.

If only it were true though and my original point of it being a blanket limit change means that actually it’s not 2-3 minutes at 20 whilst you go through.

Entire routes are now 20mph from point to point because it’s borough wide. Hence the lack of common sense in my opinion of just making every road a 20 they consider residential.

Well unless it’s a TLF route, because it’s ok for buses to do 30 in residential areas just not cars.
 
If only it were true though and my original point of it being a blanket limit change means that actually it’s not 2-3 minutes at 20 whilst you go through.

Entire routes are now 20mph from point to point because it’s borough wide. Hence the lack of common sense in my opinion of just making every road a 20 they consider residential.

Well unless it’s a TLF route, because it’s ok for buses to do 30 in residential areas just not cars.
Is it really that bad? I’ve just had a look at Croydon Council’s maps of 20mph roads and there are plenty through roads that remain at 30. Now I’ll admit that I’m most definitely one to use routes that avoid busy main roads and I can see many in Croydon that would be suitable. But unless doing a grand tour of Croydon I should think you’re only looking at 3 or 4 miles at the most on those residential roads. IF you could do a steady 30mph on those roads it would take an extra 4 minutes to cover 4 miles against doing 20. But those roads include several places where you’d have to stop or negotiate junctions, so the time saving would more realistically be closer to 2 minutes or less. Is it worth getting bothered about?
 
I passed through Croydon a few times, I swear I never saw 15MPH.
 
While I accept your contention in general , in present day political climate , some roads may have lower speed limits purely to gain votes or score points against opposition...

I think there's an element of dogma involved as well. And the type of people who enter local politics may also tend to be from self-selecting peer groups that tend towards views and opinions.
 
Is it really that bad? I’ve just had a look at Croydon Council’s maps of 20mph roads and there are plenty through roads that remain at 30. Now I’ll admit that I’m most definitely one to use routes that avoid busy main roads and I can see many in Croydon that would be suitable. But unless doing a grand tour of Croydon I should think you’re only looking at 3 or 4 miles at the most on those residential roads. IF you could do a steady 30mph on those roads it would take an extra 4 minutes to cover 4 miles against doing 20. But those roads include several places where you’d have to stop or negotiate junctions, so the time saving would more realistically be closer to 2 minutes or less. Is it worth getting bothered about?

I come under a Croydon postcode, I don't live in Central Croydon.

Through the center of town, it's not likely you'd do more than that. I'm talking about further out where you head out to Purley/Kenley/Coulsdon where it's not built up but everywhere has just had a 20mph limit imposed.

It's not a huge bother, it was just a genuine question really. Like I've said a few times in the thread, I think a 20 zone in certain areas makes sense and can be imposed for safety purposes. I think what bothers me more is that lack of thought behind it, just blanket the entire area in 20 signs when it's not clear cut as to if it's a benefit to the actual public. In fact there are some genuinely logical arguments against it.

Also, I wonder how much it cost them to put up 20 signs along every single road in the area? Far more than there were 30 signs that's for sure. Frustrating as a motorist seeing money spent on that when you're desperately trying to avoid hundreds of potholes at the same time. That's another discussion entirely but I don't think it's an invalid point.
 
Pedestrians are almost 10 times more likely to be fatally wounded at 30 mph than at 20. At 20 there is a 2.5% chance of being killed, at 30 it rises to around 20%
Also there is much less chance if they stay out of the road when vehicles are on it.

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I think there's an element of dogma involved as well. And the type of people who enter local politics may also tend to be from self-selecting peer groups that tend towards views and opinions.

And it’s all part of job creation scheme, multitude of unnecessary white lines, expensive radar controlled speed signs etc. Have you noticed increase cheap re-surfacing jobs, end of financial year.
 
Whats the chance of a pedestrian being fatally wounded at 5mph? I bet its a fair bit less than 2.5% so lets have 5mph speed limits. In fact lets employ someone to walk in front of our cars with a flag to warn everyone that we are on our way.....ohh hang on thats what used to happen back in 1890.
Love Statistics, try this one, statistically there were less fatalities on the roads before speed limits were ever introduced, so perhaps as a road safety initiative all speed limits ought to be removed. As an alternative we can try seeing statistics for what they really are [emoji6]

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