The 30mph speed limit is unsuitable for much of today's driving conditons

[meeeb]

And is the reason I said relative constant.... An F1 driver will have better reaction time but so what ? The assumption o the Highway Code is that the reaction time is 0.7 of a second. and that is what the average person can do and is the same at all speeds.
And the stopping distances in the test/link I have provided are average and are covering a lot of different cars so as to be representative. That analysis was to the point that stopping distance over the years has not actually improved and also clarify the relationship between reaction and stopping distance and that is not speculation but a fact.
The discussion here is not if its good/safe to go faster/slower but how drivers interpret what is a safe speed rightly or wrongly..TG

A quote from your link: "Furthermore,because professional drivers are used in these experiments,the distance it takes to stop the vehicle may be shorter than when the vehicle is driven by the average driver." In addition it is quite possible, if not probable, that because of the nature of the tests, the driver was fully prepared for the heavy braking. The tests are therefore not relevant to real-world driving. See below.

One worrying trend Ive noticed and this is about me as a driver is that I seem to become less alert when driving at 30.

Very telling. At least you have recognised this and can do something about it.

 

[BTB 500]

Because kinetic energy is proportional to velocity squared.

So going from 30 to 40mph almost doubles the vehicles kinetic energy, or, in other words, it's potential to damage something!

True, but relatively little of that kinetic energy is lost/transferred in hitting a pedestrian (the car's speed isn't reduced much solely by the collision).

Obviously a 40 mph impact is still going to be worse than a 30 mph one though.

 

[developer]

Not being rude but, if you did a two hour IAM drive and felt "forced" to stick to 30mph max in 30mph zones then you clearly didn't get much out of the session.

Either the instructor failed to instil in you the importance and value of adhering to the 30 limit or you weren't receptive to, or aware of, the abundant potential hazards that gave rise to a 30 limit being in place.

None taken PRP - the instructor was as good as I'd expect an IAM observer to be (though it's quite strange being told to slow down at 33mph).

My point wasn't about his ability or my receptiveness - it was about how, at 30mph, I became the bottleneck.

 

[Mrhanky]

True, but relatively little of that kinetic energy is lost/transferred in hitting a pedestrian (the car's speed isn't reduced much solely by the collision).

Obviously a 40 mph impact is still going to be worse than a 30 mph one though.

Not worse, lethal I would have imagined

 

[Giantvanman]

One worrying trend Ive noticed and this is about me as a driver is that I seem to become less alert when driving at 30.

Start doing an internal commentary. With some practice, not only will the gaps (in your internal monologue) become less but your observation will increase dramatically. End result, you see and concentrate more.

 

[Mrhanky]

Start doing an internal commentary. With some practice, not only will the gaps (in your internal monologue) become less but your observation will increase dramatically. End result, you see and concentrate more.

Good idea and its what I do normally, just for some reason as 30mph feels slow and safe I relax more.

In 21 years of driving Ive never had an accident but Im very aware I dont want to become complacent with my driving.

 

[Jeff666]

So read a lot of this to and fro... opinions vary as always.. I think for minor infringements ( yes subjective but we know what we mean) rather than the fine and or awareness course a 2 week ban would impact most people (not on the license similar to the awareness course) . That would be a far greater and more thought provoking position.. Again the 3 hits and you're out... A fine is annoying, the inability to do what you want when you want is massive. School run, going to work, afternoon out...

Assumes law abiding indiduals... beyond that is the dark side

 

[Bellow]

It is to slow if people want to jump in front of my car without looking it is hardly my fault they should learn the green cross code. If we all had the attitude you can't do this or that as someone my get hurt no one would be doing anything at all.

Absolutely! If they're adults.
If they are adults and I'm doing 30 or lower then I can scarcely be more wrong them than - as good as a get-out-jail-card for me.
If they are a child? Or a toddler who just escaped their parent's clutches momentarily?

Two damned good reasons I'll be sticking to 30 when the sign shows that number.

 

[Stratman]

Modern braking systems may have improved, but the MOT still only requires 50% brake efficiency for post '67 vehicles and just 40% for earlier.

Those vehicles have just as much right to be on the road as any other. Should the 30 limit be raised for them too?

 

[jotter22]

So is the driver who drives at 30MPH in a 40mph limit and then drives at 25MPH because it is drizzling or 15MPH because there is some snow at the edge of the road not just as dangerous as someone exceeding the speed limit by the odd MPH?

Tony.

 

[Sp!ke]

I treat speed limits as a guide.

Sometimes they are too low and sometimes they are too high.

Most residential 30 limits round housing estates should probably be driven at 20mph, whereas there are many 30 zones where 40 is more appropriate (depending on the time of day).

If your speed is appropriate to the conditions, I would like to think that a few mph over the limit will be ignored by the boys in blue but don't bank on it.

What I do find a little irritating is newly reduced speed restrictions. An unchanged road that for the past 20 years I had been quite safe driving along at 60mph.... suddenly I'm a danger for driving at 45mph. There are so many NSL roads now reduced to 40 - why?

 

[itaintemeyouno]

So is the driver who drives at 30MPH in a 40mph limit and then drives at 25MPH because it is drizzling or 15MPH because there is some snow at the edge of the road not just as dangerous as someone exceeding the speed limit by the odd MPH?

Tony.

Red herring as it is irrelevant to the thread.

 

[prprandall51]

What I do find a little irritating is newly reduced speed restrictions. An unchanged road that for the past 20 years I had been quite safe driving along at 60mph.... suddenly I'm a danger for driving at 45mph. There are so many NSL roads now reduced to 40 - why?

I get very frustrated by councils such as Gloucestershire and Oxfordshire, which have blanket downgraded every NSL single-carriageway A-Road down to 50mph.

It's a joke, you are driving along an NSL road and then you come across two signs directly next to each other: "Welcome to Gloucestershire" and "50" and every single B-road turn-off goes back up to NSL!

 

[Giantvanman]

So is the driver who drives at 30MPH in a 40mph limit and then drives at 25MPH because it is drizzling or 15MPH because there is some snow at the edge of the road not just as dangerous as someone exceeding the speed limit by the odd MPH?

Tony.

No. They are limits, not targets.

It is their assessment of the road conditions they are driving by, not anyone else's.
No, the danger comes from the impatient and unappreciative. What's wrong with someone driving within their comfort zone? They are driving their car for their benefit, not anyone else's.

 

[Dieselman]

People's ability to think quickly and correctly is not a constant. I think it is better to legislate taking into consideration the worst rather than the best, especially most people's reluctance to acknowledge they aren't as good a driver as they think they are.

Time for an advanced driving course perhaps. <Snigger>

 

[Dieselman]

And is the reason I said relative constant.... An F1 driver will have better reaction time but so what ?

Tests show they don't. Reaction time is exactly that, the ability for the brain to react.

A simple test is to hod a ruler vertically above someones open thumb and fore-finger.
Without warning let it drop and get them to grip it with thumb and fore-finger, to stop it.

Pretty well all able bodied people will catch it at a similar point along the rulers length.

 

[Dieselman]

True, but relatively little of that kinetic energy is lost/transferred in hitting a pedestrian (the car's speed isn't reduced much solely by the collision).

Obviously a 40 mph impact is still going to be worse than a 30 mph one though.

As you say, the car loses little energy, but that translates to a huge impact and transfer of energy to the pedestrian.

If one is hit at 30mph, they go from 0-14.5 metres per second in less than 0.2 seconds.

 

[theogeor]

Tests show they don't. Reaction time is exactly that, the ability for the brain to react.

A simple test is to hod a ruler vertically above someones open thumb and fore-finger.
Without warning let it drop and get them to grip it with thumb and fore-finger, to stop it.

Pretty well all able bodied people will catch it at a similar point along the rulers length.

Allow me to disagree. Scientific studies shows athletes and F1 drivers and few other sports have better reaction time from the average person. Might be marginal but is better. Now if that is going to make significant difference on every day speeds then is another matter

Theo

 

[guydewdney]

r

I sometimes find on NSL roads there are people who drive somewhat below the limit , even though it may be safe and legal to go faster . Without safe opportunities to overtake , everyone is then held up .

And then someone makes a rash descision to overtake in a oorly judged spot due to their fustration, and an accident occours. No blame whatsoever is put upon the numpty driving at 22mph in a rural nsl zone.

Down ere in the west country we get it all the time. My wife and i have a competition on finding the greatest difference twixt limit and driver, so far she is the winner at 18mph in a 60 (open road, no tractor etc).

 

[geraldrobins]

It is to slow if people want to jump in front of my car without looking it is hardly my fault they should learn the green cross code. If we all had the attitude you can't do this or that as someone my get hurt no one would be doing anything at all.

If only everyone was perfect!! And what about children who might be distracted??? Its not all about fault the speed limits are to protect people.