20mph Speed Limits

[Parrot of Doom]

Come on, this is basic biology. A human can run at 20 mph. That's what the body, our bodies, are designed for. Impact collisions above this speed are lethal, your internal organs become detached and you bleed to death, if the trauma of the impact itself doesn't kill you. Our bodies are designed to withstand running into a tree at 20mph tops. Above 20mph you are much more likely to die. 20mph zones save lives because impact speeds are at a safer level.

Impact speeds are almost always well below free travelling speeds.

 

[DrSquirrel]

I'm not opposed to them. I'm just not keen on bringing in a law that gives a guy in 2 tons of steel next to me, more reason to dislike me. My point is that if cyclists want them, they should at least abide by them.

They, Cyclists - neither of these are me, I don't want them neither would I adhere to them (since I don't have to).

"Motorists" are going to hate on cyclists for some reason or other, all it does is shift their excuses.

Anyway, that guy in 2 tons of steel should be driving slower than my sub 0.1 tons of mass...

 

[clarion]

Mikey, you are right. Greenwich is a Royal Park, so the speed limits do apply to us too, just as they do in Richmond Park. I admit I forgot this when I was there for the first time last weekend, and did ride a shade over 20mph, though I was on fixed, so I didn't want to go very fast. It is surprising how much you have to hold back to stay legal in Richmond Park, and how many cars steam past when you do.

For information, the Royal Parks are:

Bushy Park
Green Park
Richmond Park
The Regent's Park
Brompton Cemetery
St James's Park
Kensington Gardens
Greenwich Park
Hyde Park

From http://www.royalparks.gov.uk/

 

[Norm]

Yep.

TRL 421,

Wow, I'm impressed.

 

[John the Monkey]

I'd rather motorists paid attention to their surroundings and relevant hazards, than look at their speedometer every 5 seconds to ensure they're not exceeding an arbitrary limit.

If they can't maintain a constant speed without doing this, why the hell are they on the road AT ALL?

 

[BentMikey]

If you can't know your speed when you're driving, and know whether you're at or below the speed limit, then I'd argue you don't deserve to be driving, and shouldn't have passed your test.

 

[dawesome]

As a driver of 20-odd years and someone who took and passed the IAM course, I think my driving isn't too bad.

BTW, I break the speed limit all the time - pretty much every day.

Come again?

 

[StuartG]

While that points strongly towards correlation, the data is still pretty crap, or at least used in an odd way, which I'm going to go out on a limb for and claim is being used to bias an argument.

I have not seen the study for this so cannot comment on its credibility. Except that it is not that far removed by the first credible study covering 20mph urban speed limits (in London). That showed KSI's down over 40% and higher amongst the young. That study (you can find some links to it in the Campaigning sub-forum) showed that the passive measures (snoring plods) reduced average speeds on these roads from around 27 mph to 17 mph.

Its well worth reading that report. It is very honest in reporting the limitations of the study and the need for further studies. However, the headline reduction is so striking that this is a report that cannot be ignored. AFAIK the results have not been seriously questioned so far and I'm sure there are many interested parties wishing to undermine them. So it looks like the best info we have on the effects of reducing motor vehicle speeds in urban areas.

As people elsewhere have sadly commented - speed signs are of little use without enforcement. In this case through your suspension.

 

[dawesome]

Impact speeds are almost always well below free travelling speeds.

A dangerous, dishonest claim comprehensively debunked here:

If we consider a car being driven at 36mph, then that car’s residual speed at the 12 metre marker may not have reduced at all – the car would possibly have slowed down by 1mph to 35mph if the driver has good reactions, but nearly all, if not all, of the distance will be taken up with thinking rather than braking. (Certainly as speeds approach and then exceed 40mph there is absolutely no chance of the driver reducing their speed at all by the impact distance of 12 metres.) A residual speed of at best 35mph is inevitably catastrophic to the human body. Using the same calculations, this is the equivalent of a child falling backwards out of a fifth floor apartment onto concrete. No-one would expect a child to survive that fall.

This clearly demonstrates the stupidity of Safe Speed when they say that ‘very few pedestrian impacts take place at free travelling speeds’. In fact, any driver choosing to drive at 36mph or above who hits a child 12 metres in front of them is almost inevitably going to be travelling at their so-called ‘free travelling speed’. Parents don’t let their children hang around on fifth floor window ledges. But many drivers in the UK, many of whom are parents, do drive above 30mph in their own communities. This is a comparison everyone can understand.



http://www.brake.org.uk/take-action/speech-to-speed-congress-2010-by-mary-williams-obe-brake-ce.htm

I have not seen the study for this so cannot comment on its credibility. Except that it is not that far removed by the first credible study covering 20mph urban speed limits (in London). That showed KSI's down over 40% and higher amongst the young. That study (you can find some links to it in the Campaigning sub-forum) showed that the passive measures (snoring plods) reduced average speeds on these roads from around 27 mph to 17 mph.

Its well worth reading that report. It is very honest in reporting the limitations of the study and the need for further studies. However, the headline reduction is so striking that this is a report that cannot be ignored. AFAIK the results have not been seriously questioned so far and I'm sure there are many interested parties wishing to undermine them. So it looks like the best info we have on the effects of reducing motor vehicle speeds in urban areas.

As people elsewhere have sadly commented - speed signs are of little use without enforcement. In this case through your suspension.

This is quite correct:

Results The introduction of 20 mph zones was associated with a 41.9% (95% confidence interval 36.0% to 47.8%) reduction in road casualties, after adjustment for underlying time trends. The percentage reduction was greatest in younger children and greater for the category of killed or seriously injured casualties than for minor injuries. There was no evidence of casualty migration to areas adjacent to 20 mph zones, where casualties also fell slightly by an average of 8.0% (4.4% to 11.5%).

Conclusions 20 mph zones are effective measures for reducing road injuries and deaths.





http://www.bmj.com/content/339/bmj....FIRSTINDEX=0&sortspec=date&resourcetype=HWCIT

 

[MacB]

It's pretty straightforward. Higher speeds increase the likelihood of collisions and increase the severity of these injuries. The only reason they're using different years is because the 20mph zones didn't exist in different years, obviously. Speeding is reported as the number one anti-social behaviour in the British Crime Survey, unless you are arguing that drivers should drive at any speed they like and use public roads as their own personal racetrack I'm not sure what your point is. Do you know the difference in the likelihood of death at 20 mph collisions versus speeds above 30?

What about speed bumps, as a cyclist I've found road furniture like speedbumps, chicanes, rumblestrips, pinchpoints have actually increased my motorist/cyclist negative interaction ratio...to the point that I will avoid cycling on certain roads which would otherwise be ideal. I also have concerns that these measures can focus a drivers attention away from their peripheral vision.

I don't disagree around 20mph limits I just question the methodology used to enforce them.

 

[StuartG]

As a driver of 20-odd years and someone who took and passed the IAM course, I think my driving isn't too bad ...

BTW, I break the speed limit all the time ...

93% of drivers think they are above average: http://www.cheapcarinsurance.net/above-avarege-driver/
At least 43% of them are deluded. I think that includes you.

Clean record = safe driver? Well if you speed every day that says something dreadful about enforcement. You are just the person (self confident dangerous criminal) from whom we should be removing the driving licence.

Tell me you are really trolling ... please!

 

[StuartG]

What about speed bumps, as a cyclist I've found road furniture like speedbumps, chicanes, rumblestrips, pinchpoints have actually increased my motorist/cyclist negative interaction ratio...to the point that I will avoid cycling on certain roads which would otherwise be ideal. I also have concerns that these measures can focus a drivers attention away from their peripheral vision.

The danger is you are talking about perception and not facts (as best we can determine them). I, as a motorist and a cyclists, hate bumps. I think they divert my attention. But the bottom line is statistics point very strongly that you are safer on a 20mph humped street than a 30mph unhumped one. By avoiding them you may paradoxically be putting yourself in greater danger.

 

[Little yellow Brompton]

I'm not opposed to them. I'm just not keen on bringing in a law that gives a guy in 2 tons of steel next to me, more reason to dislike me. My point is that if cyclists want them, they should at least abide by them.

I would like a 20 MPH* limit for motor vehicles on some part of my route. When I'm in a motorvehicle I will abide by it, in the same way I abide by the one way system. When I'm not in a motorvehicle I feel no obligation whatsoever to abide by the law, in the same way I quite happily walk in the opposite direction of the one way system.

 

[StuartG]

46% no?

Correct 46% is bigger than 43%. Seriously it depends what you mean by 'them' - all drivers or above average drivers. My apologies for misleading the great British public with some Swedish view of a nation of which we know so little - except they ain't going to be hit by UARS.

(As predicted by NASA who eksewhere have said they can't predict where it is going to crash until after the event. Shows the guts of those astronauts who sat on top of one of NASA's creations!).

 

[MacB]

The danger is you are talking about perception and not facts (as best we can determine them). I, as a motorist and a cyclists, hate bumps. I think they divert my attention. But the bottom line is statistics point very strongly that you are safer on a 20mph humped street than a 30mph unhumped one. By avoiding them you may paradoxically be putting yourself in greater danger.

But I'm not disagreeing with the 20mph I'm just not convinced that an alternative enforcement method wouldn't be an even greater improvement. I'm also not sure I'm just talking about perception, I have experienced extremely erratic driver behaviour around pinchpoints and partial width speed bumps in particular. It may, or may not, be as dangerous as behaviour on unrestricted roads but it clearly only occurs due to the presence of road furniture.

My view is pretty simple, we limit the speed at source, so in car limiters, the technology exists and it would be effective. Others disagree with this as they believe it should be tackled via driver skills and training, and that without this people would just drive pedal to floor like a dodgem car, if limiting tech was used. I don't know if they would but can't discount the possibility, but I'd be prepared to give it a try.