FAO anyone who supports the 20mph limits..

[Notters]

Tell us more.

The thing for me is watching people accelerate up to 30-40 MPH in Brighton, and then stopping at traffic lights for a little longer... the average speed across Brighton is below 20MPH for sure

I'll try and run a model with the two speeds later. Breaking and accelerating is certainly a problem, especially where there are speed bumps.

 

[Driver8]

20mph gives everyone a fair chance, whether it is pedestrians crossing the road or other cars pulling out from junctions. There was never any real point in racing to every red light anyway because 20mph doesn’t add to the journey time, it just makes driving more chilled.

Last year I had a young lad of about 7-8 suddenly run out in front of me in Blatchington Road, to get to his brother on the other side, and doing just the 20mph only resulted in the child bursting into tears when I screeched to a halt. I have replayed that scene in my head since then but with me doing 30mph, and it could have been quite messy.

Had you been doing 30 mph you would have passed him before he ran out.

 

[Diego Napier]

20mph gives everyone a fair chance, whether it is pedestrians crossing the road or other cars pulling out from junctions. There was never any real point in racing to every red light anyway because 20mph doesn’t add to the journey time, it just makes driving more chilled.

 

[MattBackHome]

I'll try and run a model with the two speeds later. Breaking and accelerating is certainly a problem, especially where there are speed bumps.

I'd be genuinely interested to hear more about this.

 

[Notters]

I'd be genuinely interested to hear more about this.

Unfortunately I'm massively busy but take a look at this graph. It's NOx (oxides of nitrogen) that we're particularly concerned about in terms of health effects.

 

[Chicken Run]

Sure. I wasn't in favour until I did a Speed Awareness Course

Agree with the above

 

[Chicken Run]

A good many folk break the 30 mph zones often doing 34-36, the 20 mph zones naturally reduce this to 24-26 which in a collision gives everyone a chance, same principal for not increasing motorways to 80mph.

 

[TWOCHOICEStom]

Unfortunately I'm massively busy but take a look at this graph. It's NOx (oxides of nitrogen) that we're particularly concerned about in terms of health effects.

Not often you get an NSCer to run a statistical model to prove a point, fair play!

But. Is some of that danger not offset with the increasingly low emissions from modern cars?

 

[symyjym]

Unfortunately I'm massively busy but take a look at this graph. It's NOx (oxides of nitrogen) that we're particularly concerned about in terms of health effects.

I am not too sure if this gives a true representation because to me this graph looks like the data is made up of constant speeds rather than real driving conditions.

If one drives a car with minimal gear changing and less frequent stopping, it would probably beat the pollution data of someone who is always accelerating to 30mph and then hard breaking between every red light and junction (effectively wasting the energy that has been used) . The most efficient way to drive is to avoid quick acceleration and breaking as much as possible.

I am sure that some drivers may only use 3rd or 4th gear in 20mph, where as I will slip my car into 5th asap and often go to neutral and use momentum to roll up to the next lights or junction, whilst hoping the lights will change when I get there and avoiding having to use 1st. Pollution has as much to do with driving style as it does speed surely?

 

[Brovion]

I've got no problem with the 20mph limits for safety reasons, but what did really really piss me off was the bollocks claim that it 'improved air quality'. No it didn't, it was a trade-off as the people of Storrington* found. Thank you Notters for finally nailing that lie. No chance of ***** like Davey recanting though.


*Storrington residents were worried about vehicle speed through the town centre so they introduced methods of slowing it down. The result was that that the air quality deteriorated badly.

 

[studio150]

I have lots of problems with a blanket 20mph limit, starting with the 'consultant process' which just seems to be send out a survey, and then say everyone if favour, without commenting on the actual number of forms returned and of those that said yes, what percentage is that of all the forms regardless of whether returned or not. i would suggest that many are not engaged in the process and just accept the position.

The publicity around the introduction of 20mph limits includes that it will lead to more people walking and cycling around the streets. I have seen no evidence of this at all. Also if a cycle lane is present in an area that is now 20mph why has this not be removed given that cyclists are supposed to feel safer in such areas.

If you look at most incidents involving vehicles in urban areas, most of these happen at junctions and only result in minor bent metal, and at speeds which are slowly down below 20mph.

The headline crashes more often than not involve stolen cars, racing and excessive speeds where the vehicle is travellin much more than 30mph, so the introduction of a 20mph limit makes no difference at all.

You then get the OAPs with automatic cars who seem to be unable to tell the difference between the pedals and rather than braking speed up.

There is also the advancement of vehicle technology, where cars are coming with more and more safety features to avoid crashes. Brakes are far better than previously and with AEB on an increasing number of vehicles, the breaking is assisted by the onboard technology.

The only thing that is not improving is the ability to cross the road correctly and cyclists. Maybe we should instead start with the American approach of clamping down on jaywalking and ensure that everyone only crosses the road at approved sites and when the green man says it is safe to do so.

What happens when autonomous cars rule the roads, with all the technology to avoid everything else on the road, are we still stuck with a speed limit that should be left in the early 20th Century.

 

[MattBackHome]

Unfortunately I'm massively busy but take a look at this graph. It's NOx (oxides of nitrogen) that we're particularly concerned about in terms of health effects.

Thanks for this. So the trade off is between the marginal increase (30-20) in NOx emissions and the increase in Road Safety.

 

[Man of Harveys]

I have lots of problems with a blanket 20mph limit, starting with the 'consultant process' which just seems to be send out a survey, and then say everyone if favour, without commenting on the actual number of forms returned and of those that said yes, what percentage is that of all the forms regardless of whether returned or not. i would suggest that many are not engaged in the process and just accept the position.

The publicity around the introduction of 20mph limits includes that it will lead to more people walking and cycling around the streets. I have seen no evidence of this at all. Also if a cycle lane is present in an area that is now 20mph why has this not be removed given that cyclists are supposed to feel safer in such areas.

If you look at most incidents involving vehicles in urban areas, most of these happen at junctions and only result in minor bent metal, and at speeds which are slowly down below 20mph.

The headline crashes more often than not involve stolen cars, racing and excessive speeds where the vehicle is travellin much more than 30mph, so the introduction of a 20mph limit makes no difference at all.

You then get the OAPs with automatic cars who seem to be unable to tell the difference between the pedals and rather than braking speed up.

There is also the advancement of vehicle technology, where cars are coming with more and more safety features to avoid crashes. Brakes are far better than previously and with AEB on an increasing number of vehicles, the breaking is assisted by the onboard technology.

The only thing that is not improving is the ability to cross the road correctly and cyclists. Maybe we should instead start with the American approach of clamping down on jaywalking and ensure that everyone only crosses the road at approved sites and when the green man says it is safe to do so.

What happens when autonomous cars rule the roads, with all the technology to avoid everything else on the road, are we still stuck with a speed limit that should be left in the early 20th Century.

That's all well and good Mr Clarkson but did you really hit that producer for not getting your dinner?

 

[Bold Seagull]

I'm in support of it.

As a cyclist, pedestrian and driver around the city it is, in my opinion noticeably safer.

Not because everyone is doing 20mph, but because instead of drivers doing 35 or so in a 30 zone, they are doing 25 - 30 in the 20mph zone, therefore the 20 zones while not keeping everyone to exactly 20 are keeping everyone 30mph or below.

At slower speeds people are approaching junctions more safely, having more time to observe everything around them, and generally taking more care.

 

[jackanada]

The problem is that there is an entirely natural and understandable tendency to only focus on your own safety, or the safety of your passengers. In a car you are naturally far safer than other road users (except HGV drivers). To prevent speeding in urban areas, whether measured by arbitrary limits or a more considered weighing of the conditions I suggest that in urban areas car airbags deactivate and instead a foot long spike protudes from the steering wheel. Everyone would drive exceedingly cautiously.

 

[jackanada]

With specific regard to 20mph speed limits I like the idea that someone caught doing 40 in a 20mph zone could potentially lose their licence for going twice the speed limit. 3pts for over 30, speed awareness/ticking off over 25 and 20-25 mainly ignored.

 

[Notters]

But. Is some of that danger not offset with the increasingly low emissions from modern cars?

I am not too sure if this gives a true representation because to me this graph looks like the data is made up of constant speeds rather than real driving conditions.

If one drives a car with minimal gear changing and less frequent stopping, it would probably beat the pollution data of someone who is always accelerating to 30mph and then hard breaking between every red light and junction (effectively wasting the energy that has been used) . The most efficient way to drive is to avoid quick acceleration and breaking as much as possible.

I am sure that some drivers may only use 3rd or 4th gear in 20mph, where as I will slip my car into 5th asap and often go to neutral and use momentum to roll up to the next lights or junction, whilst hoping the lights will change when I get there and avoiding having to use 1st. Pollution has as much to do with driving style as it does speed surely?

You're right to point out that the issue is far more complicated than I've made out. We can only do so much to model for people's driving style. The important thing to realise is that it's the main arterial routes with large flows of traffic that are the issue, as these are the only places where exceedences of the the National Air Quality Objectives (http://uk-air.defra.gov.uk/assets/documents/National_air_quality_objectives.pdf) are likely to occur at sensitive receptors (i.e. houses). In particular (for Brighton), Preston Road, Ditchling Road, Old Shoreham Road, Davigdor Road etc. It is the long term (annual average) pollutant concentrations that are the issue and therefore long term (annual average) traffic speeds which generally matter. I would argue that these routes, at least, should remain at 30mph. People will naturally (apart from a few idiots) drive slower on smaller residential streets with lots of parked cars anyway.

I've got no problem with the 20mph limits for safety reasons, but what did really really piss me off was the bollocks claim that it 'improved air quality'. No it didn't, it was a trade-off as the people of Storrington* found. Thank you Notters for finally nailing that lie. No chance of ***** like Davey recanting though.

*Storrington residents were worried about vehicle speed through the town centre so they introduced methods of slowing it down. The result was that that the air quality deteriorated badly.

Yep, there's a massive issue in Storrington. I frequently work with the Horsham air quality officer and I know it's a massive headache for her.

Thanks for this. So the trade off is between the marginal increase (30-20) in NOx emissions and the increase in Road Safety.

Yup, pretty much. and bear in mind that air pollution, mostly from vehicle emissions, is estimated to cause around 30,000 deaths per year in the UK - far more than those involved in road collisions.

As a cyclist, pedestrian and driver around the city it is, in my opinion noticeably safer.

...and I think that's because people getting runover is noticeable, whereas deaths from COPD and other diseases associated with air pollution; along with the pollution itself, are far from obvious.

You know that advert with someone smoking a cigarette in a car, where they say something along the lines of "if you could see all the chemicals coming out of that cigarette, you wouldn't be doing it". Well there's a damn site more coming out of the back of the car, believe me!

One thing is for sure, knowing as much as I do now, I would never buy/live in a house next to a main road.

 

[MattBackHome]

One thing is for sure, knowing as much as I do now, I would never buy/live in a house next to a main road.

Couple of last questions from me (knowing you're busy!)

When you say next to a main road, do you mean directly adjacent to a main road? How close is too close?

Also are there any decent online resources to read up further on this stuff - whilst avoiding the political point scoring on either side? Cheers

 

[Bold Seagull]

You're right to point out that the issue is far more complicated than I've made out. We can only do so much to model for people's driving style. The important thing to realise is that it's the main arterial routes with large flows of traffic that are the issue, as these are the only places where exceedences of the the National Air Quality Objectives (http://uk-air.defra.gov.uk/assets/documents/National_air_quality_objectives.pdf) are likely to occur at sensitive receptors (i.e. houses). In particular (for Brighton), Preston Road, Ditchling Road, Old Shoreham Road, Davigdor Road etc. It is the long term (annual average) pollutant concentrations that are the issue and therefore long term (annual average) traffic speeds which generally matter. I would argue that these routes, at least, should remain at 30mph. People will naturally (apart from a few idiots) drive slower on smaller residential streets with lots of parked cars anyway.


Yep, there's a massive issue in Storrington. I frequently work with the Horsham air quality officer and I know it's a massive headache for her.



Yup, pretty much. and bear in mind that air pollution, mostly from vehicle emissions, is estimated to cause around 30,000 deaths per year in the UK - far more than those involved in road collisions.



...and I think that's because people getting runover is noticeable, whereas deaths from COPD and other diseases associated with air pollution; along with the pollution itself, are far from obvious.

You know that advert with someone smoking a cigarette in a car, where they say something along the lines of "if you could see all the chemicals coming out of that cigarette, you wouldn't be doing it". Well there's a damn site more coming out of the back of the car, believe me!

One thing is for sure, knowing as much as I do now, I would never buy/live in a house next to a main road.

Notters, I've also noticed that slower traffic speeds mean that there is less congestion at crucial pinch points. The faster you travel the more vehicles you get from one pinch point to the next. While your argument that there is more pollution from a car doing 20 than 30, there is far more pollution from toe to tail queuing traffic. If slowing traffic down reduces the flow of traffic between pinch points thereby reducing the numbers of queuing traffic, your argument is dead in the water.

As for people naturally driving sensibly in residential streets - depends on the street. If its a cut through like Hallyburton Road avoiding the rail crossing on Boundary Road, then people fly up there. That has changed to 20mph, and while the majority probably still average around 30 or just under, it has greatly reduced the number flying up there at 35 mph+ - therefore the 20mph zone has done it's job in my opinion.

I agree Old Shoreham Road should probably stay a 30, but that said, it's still treated as 40mph, even though as far back as Southwick to Hove Rec. it is a 30mph limit. Drive along there at 30mph and you will be overtaken by everyone. You'll be overtaken by most even if you're doing 35mph. Perhaps enforcement is the issue there rather than further reducing the speed limit.

 

[symyjym]

With specific regard to 20mph speed limits I like the idea that someone caught doing 40 in a 20mph zone could potentially lose their licence for going twice the speed limit. 3pts for over 30, speed awareness/ticking off over 25 and 20-25 mainly ignored.

Yep, it's not really about 20mph it's about stopping excessive speeding and aggressive driving. If everyone naturally drove safe and considerately we wouldn’t need any speed limits let alone 20mph ones.