plenty of small city cars around and more appearing all the time
Which are also more efficient at 30 than 20.
Bike Forum
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Institute of Advanced Motorists - cycling poll
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Which are also more efficient at 30 than 20.Posted 2 years ago # -
A racer - your rac or AA link ( whichever it was) had the proof that you only use less petrol at a steady 30 mph and under ideal conditions. If you are accelerating and slowing then even that link / piece of research showed that you use more petrol in a 30 mph limit than a 20. Even the steady state its only some cars dependent on gearing.
to say otherwise is ludicrous. It takes 50 % more energy to accelerate to 30 mph than it does to 20 mph.
Hoist by your own petard
Posted 2 years ago # -
The AA accepts that targeted 20 mph speed limits in residential areas are popular and improve safety. Along shorter roads with junctions and roundabouts, limiting acceleration to up to 20 mph reduces fuel consumption.
Now this is from an organisation and a piece of work that set out to discredit 20 mph limits. Even they have to accept that it actually reduces petrol consumption
http://www.theaa.com/public_affairs/news/20mph-roads-emissions.html
Posted 2 years ago # -
Here is some good real non biased research on 20 mph limits.
Posted 2 years ago # -
How many times do I have to say it before you read what I'm writing, TJ? Go back through my posts and find the bit where I say most of my driving in 30 limits is stop start. Can't find it? Well maybe that's because I can generally do a steady 30, and have been saying so all through this thread. That makes all your arguments irrelevant - for the driving I do in 30 limits, being restricted to 20 would mean I used more fuel, not less. Fact.
It takes 50 % more energy to accelerate to 30 mph than it does to 20 mph.
Well actually it takes 125% more energy, but that's kind of beside the point, because if you can maintain a steady 30mph (you seem to keep ignoring that fact that most of the driving I do in 30 limits I'm the front of the queue, so can do that), then to suggest the acceleration is a major factor in the total energy used is ludicrous.Even the steady state its only some cars dependent on gearing.
Er, no. Actually it's all conventional cars on the road today, and for the foreseeable future.Though it seems you're happy to prove my point for me. Did you bother reading the links you've provided? I mean you picked one lonely sentence out of that AA report which doesn't disprove my point at all (do I need to remind you again that I'm not talking about stop/start driving), whilst it also has the following right at the top "On average, petrol car fuel consumption on longer and relatively free-flowing 20mph urban streets can worsen by 5.8 miles per gallon". Meanwhile the only actual evidence based fact in the other one is the graph which also shows that you use more fuel at 20 than 30. Yes I have read the surrounding text which is presumably what you're relying on, but all of that is just speculation, and has just about as much weight as what you're writing on this thread.
Though by introducing that web page as evidence, are you trying to make it a bit more obvious that you're just trolling? The idea that it's non biased is a joke surely? It's just about as non biased as what you're writing - just like you he's attempting to fit the available evidence to his viewpoint rather than basing conclusions on the evidence. If that's an example of the quality of his analytical thinking and use of data then I'd certainly not employ him. I'll go into more detail later, but try following his links and see whether what he claims for them supporting what he says is actually true.
Posted 2 years ago # -
Posted 2 years ago # -
Anyway (vain attempt to steer this thread back to the original point), I've done the survey and used the 'other' box to suggest compulsory cycle awarness training for all drivers. Suggest others do likewise instead of arguing/ winding each other up across the t'interweb.
Posted 2 years ago # -
There's a heavy disingenuous dose in the anti 20mph limits arguents, I suggest. Basically you just don't want to slow down. "I'm in the front of the queue" - yea ok. How do you manage to engineer it so you're always at the front of the traffic? And even if you do (which you don't) then all of the other cars don't get to be at the front. TJ makes some good points and provides good reference for the argument for ALL cars, not just the miraculous ones that always drive on the front of the traffic.
To claim that normal rules don't apply because you always drive at the front of the traffic, and then in the next paragraph to suggest that someone is selecting evidence to suit his argument is about as absurd as it gets.
Posted 2 years ago # -
...used the 'other' box to suggest compulsory cycle awarness training for all drivers
How would that work? Just as part of the driving test? I suppose that would be a start, but you're never going to get all the existing drivers with that.
Posted 2 years ago # -
Nationwide TV and all other mainstream media campaign telling everyone that cyclists are on the road by right. They are not just borrowing the gutter section of the road that other vehicles don't drive on. Even if they were taxed the fee would be zero.
Nationwide campaign showing where a bike should be positioned on the road.
Nationwide campaign for responsible and good driving. Not just getting away with it and seemingly keeping within the law - actual proper driving. Keeping as big a gap as possible and driving in your own space. Constant alertness and respect for other people. Same goes for cyclists, but car drivers have to realise that their standards stink too.
Problem solved.
Posted 2 years ago # -
TJ and GlenP both put it well.
Al seems to be thinking that 20mph zones are all about hindering him from driving at 30mph in a 30mph zone (not sure if that is quite the best driving habit for a start).
Reducing overall speed makes the whole road area, including pavements, safer for pedestrians, safer for cyclists on the road and may help to encourage even more cyclists to take to the roads as they feel safer. Increasing numbers of cyclists on the road mean less drivers, further reducing traffic noise, pollution etc.
I could continue, but I feel that Al will miss the point (again)...
Posted 2 years ago # -
TJ and GlenP both put it well.
Al seems to be thinking that 20mph zones are all about hindering him from driving at 30mph in a 30mph zone (not sure if that is quite the best driving habit for a start).
Reducing overall speed makes the whole road area, including pavements, safer for pedestrians, safer for cyclists on the road and may help to encourage even more cyclists to take to the roads as they feel safer. Increasing numbers of cyclists on the road mean less drivers, further reducing traffic noise, pollution etc.
I could continue, but I feel that Al will miss the point (again)...
Posted 2 years ago # -
I guess I am thinking about my commute - several stretches of busy but wide road where 30mph is IMO reasonable, with lights around a mile apart.
Posted 2 years ago # -
Al. No-one is suggesting converting all 30mph limit areas to 20mph. Just some of them.
We've had five (I think, it could be more) pedestrian deaths in little old Dorking in very recent years, including a friend of mine. Nothing is certain, but pretty sure that 20mph would have left all of them alive and delayed traffic to the tune of about two minutes for each pass of the High Street and one way system. We could probably also get rid of some of the bloody silly traffic lights which only got put in because drivers are too selfish and impatient to let traffic filter over junctions. If we all filtered slowly through intersections, allowing one car through each, then we wouldn't feel the need to accelerate between lights in the first place.
Posted 2 years ago # -
There's a heavy disingenuous dose in the anti 20mph limits arguents, I suggest. Basically you just don't want to slow down.
You're dead right, I don't want to slow down - why is that disingenuous though? Unless there's a good reason for driving slower, why exactly should I waste my fuel and my time? Maybe they should just bring back the red flag man if you think it's such a good idea to go slower for no good reason."I'm in the front of the queue" - yea ok. How do you manage to engineer it so you're always at the front of the traffic? And even if you do (which you don't) then all of the other cars don't get to be at the front. TJ makes some good points and provides good reference for the argument for ALL cars, not just the miraculous ones that always drive on the front of the traffic.
Obviously too subtle for you. Strange, given I think I've already said that I tend to travel at a steady 30mph in most 30 limits - apologies if I haven't yet mentioned that on this thread. Hint: most other drivers tend to drive at >30mph in a 30 limit given an open road (which they tend to get on the roads I drive on unless they encounter somebody doing 30). Oh, and if you think TJ's references are good I suggest you go back and re-read them and follow the links and work out why TJ's favourite one is factually incorrect.Posted 2 years ago # -
Al. No-one is suggesting converting all 30mph limit areas to 20mph. Just some of them.
I think TJ at least is arguing for making the majority of them in towns, including through routes into 20. I'm actually all in favour of making residential non-through routes (apart from for rat-runners) into 20 limits. A point which I agree with the AA on (despite the AA being against 20 limits according to TJ).Posted 2 years ago # -
It is disingenuous because rather than just admit that you plain don't want to slow down you feel like you need to clutch at some frankly very tenuous other arguments to justify your position. I think disingenuous is the right word for that.
20ph limits are suggested for certain areas, not as a substitute for all 30s.
Nothing you say is "too subtle for me". Actually, nothing you have said is subtle at all.
Just because you drive at 30 doesn't put you at the front of the queue at the lights. Nonsense.
Posted 2 years ago # -
Al. No-one is suggesting converting all 30mph limit areas to 20mph. Just some of them.
Oh. I thought that was pretty much exactly what TJ was advocating.
Nothing is certain, but pretty sure that 20mph would have left all of them alive
LOL!
Posted 2 years ago # -
Glad your laughing. Actually, no. What's so funny about people being dead when they wouldn't otherwise be just because drivers are selfish?
Posted 2 years ago # -
IIRC the US has a charge called 'vehicular manslaughter' - wonder if we could have a charge worded similarly?
Posted 2 years ago # -
It is disingenuous because rather than just admit that you plain don't want to slow down you feel like you need to clutch at some frankly very tenuous other arguments to justify your position
If it makes you happy, then I'll admit I don't want to slow down. I thought I'd said that with my first comment way up there - apologies if I didn't make it clear enough for you (strange given I'm not apparently being at all subtle). So pointing out that you'll use more fuel and generate more pollution travelling at 20 rather than 30 is a tenuous argument? You don't actually care about pollution and AGW any more then? Or are you suggesting I shouldn't attempt to explain why 20 limits can be a bad idea, because you're so clearly right?Nothing you say is "too subtle for me". Actually, nothing you have said is subtle at all.
Just because you drive at 30 doesn't put you at the front of the queue at the lights. Nonsense.
If it's not too subtle for you, how come you've missed the point yet again? I didn't mention anything about being at the front of the queue at the lights. Don't have any lights on most of my journeys in a 30 limit.Posted 2 years ago # -
GlenP - don't you understand that someones journey is FAR more important than another persons safety?
Posted 2 years ago # -
glenp I was commenting on your debating style, get a grip!
Posted 2 years ago # -
Because of course driving at 30 on wide straight roads with good sightlines and few pedestrians on the pavements is FAR more dangerous than driving at 20. Silly me.
Posted 2 years ago # -
al - I know you were trying to laugh at my phrase - but you also know what I meant by "pretty sure". I could spell it out - you are much less likely to die if hit at 20 than 30. You won't definitiely survive, but your chances are much higher. But you knew that, you were just being, er, you.
aracer - again you make stupid comparisons. Wide straight roads without pedestrians are not really what we are talking about. It is places like High Streets and residential roads that 20 would be much better. Actually, the limit is only a maximum - you might want to try rolling along at 20 next time the pavement is full of pedestrians and there are folk trying to cross the road and so-on. Once you get used to it you'll wonder why you didn't try it sooner.
Posted 2 years ago # -
"So pointing out that you'll use more fuel and generate more pollution travelling at 20 rather than 30 is a tenuous argument"
i doubt this has a significant effect when many urban roads are full of traffic lights and junctions anyway. constant stop/start driving will have far more of an effect on fuel consumption than speed.
In london i counted around 10 traffic lights per mile.
Posted 2 years ago # -
<sigh> go back and read my posts properly, HH. Not everybody lives in London (or Edinburgh) - I can drive for 4 or 5 miles in 30 limits through the middle of Malvern with a traffic light density of exactly 0 per mile.
glenp - I'll bet at least one of the long straight roads I drove down at 30mph today would be on TJ's list. That being a road with pavements set well back from the road behind big verges. Can't actually remember the last time I drove down the road with pavements full of peds, though I'll be sure to come back to you in 5 years or so when I next do.
BTW have you worked out my queues yet?
Posted 2 years ago # -
All I've worked out is that the kind of arterial 30 limit road that you're talking about, with pedestrians well separated from the road by verges, good visibilty, not many traffic lights etc, is not going to be a target for a 20mph limit.
So all of this discussion is completely pointless. You're talking about conditions completely different to those meriting a 20mph limit. You are using your own very specific example of roads not warranting a 20mph limit to try and put a case against 20mph limits in general.
Anywhere with rows of shops, kids playing next to the road, schools, difficult visibility, and other factors that make it not a dead straight roll-along would however be a good place to consider a 20mph limit. The stop-start nature of those roads plus the major safety benefits would defeat the slightly reduced mpg arguments.
Posted 2 years ago # -
Ah, so it was actually too subtle for you then.
I'm not convinced most people would describe many of the roads I'm talking about as "arterial" even though there isn't a safety issue with doing 30 along them.
You are using your own very specific example of roads not warranting a 20mph limit to try and put a case against 20mph limits in general.
Check out my post a little way back - I'm all in favour of 20 limits in the right place. This whole thing started off simply because I suggested doing 20 used more fuel than doing 30 and TJ disagreed - nothing more than that. That and his implication that many of the roads I'm talking about would fall under his criteria for a 20 limit. The thing is, there's not a lot to differentiate between the ones with stop start traffic you're talking about and the ones with no traffic I am (after all, the pure residential roads I'm happy to be 20 limits don't have that sort of traffic on) - the only obvious difference being the amount of traffic.Posted 2 years ago #
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