Author Topic: Lowering speed limit to 20mph increases injuries and fatalities  (Read 10512 times)

thing1

  • aka Joth
    • TandemThings
Lowering speed limit to 20mph increases injuries and fatalities
« on: 17 December, 2017, 08:50:58 pm »
So says Bath council
http://www.telegraph.co.uk/news/2017/12/17/20mph-limit-dangerous-costly-reverse-council-admits/

I'm suspicious about extrapolation of a single year's data

David Martin

  • Thats Dr Oi You thankyouverymuch
Re: Lowering speed limit to 20mph increases injuries and fatalities
« Reply #1 on: 17 December, 2017, 09:06:09 pm »
I also detest journalists who push a line with quotes but don't give a link to the report.
"By creating we think. By living we learn" - Patrick Geddes

Re: Lowering speed limit to 20mph increases injuries and fatalities
« Reply #2 on: 17 December, 2017, 09:32:08 pm »

Re: Lowering speed limit to 20mph increases injuries and fatalities
« Reply #3 on: 18 December, 2017, 04:42:34 am »
< I admit I didn't read the article >

yeahbut were the collisions which caused such injuries and fatalities at 20 mph?

Re: Lowering speed limit to 20mph increases injuries and fatalities
« Reply #4 on: 18 December, 2017, 06:12:03 am »
It is partly discussed in teh link from. the Telegraph, but we had the same claims in Portsmouth, but they were roundly dismissed as poor statistical analysis.

Most cases when you include the minor accidents will show a decrease. When these were included in Portsmouth the reality was a 20% reduction.

What was also interesting was that in some areas of Portsmouth, it was shown that due to lack of enforcement, some roads saw an increase in the speed along them!


Part of the problem was thought be a difference in perception.

Whereas pedestrians assumed the traffic would be slower and hence safer, the endemic speeding meant that the opposite

JennyB

  • Old enough to know better
Re: Lowering speed limit to 20mph increases injuries and fatalities
« Reply #5 on: 18 December, 2017, 08:47:02 am »

What was also interesting was that in some areas of Portsmouth, it was shown that due to lack of enforcement, some roads saw an increase in the speed along them!


Part of the problem was thought be a difference in perception.

Whereas pedestrians assumed the traffic would be slower and hence safer, the endemic speeding meant that the opposite

If a road looks safe at 40 mph, many  people are going to drive at 40  no matter what the limit. A 'clearly ridiculous' limit may increase that tendency.  One way to control speed is to make it visually less safe, and seem more likely tof contain pedestrians,  bikes, and other things to hit.
Jennifer - Walker of hills

Re: Lowering speed limit to 20mph increases injuries and fatalities
« Reply #6 on: 18 December, 2017, 08:57:38 am »

What was also interesting was that in some areas of Portsmouth, it was shown that due to lack of enforcement, some roads saw an increase in the speed along them!


Part of the problem was thought be a difference in perception.

Whereas pedestrians assumed the traffic would be slower and hence safer, the endemic speeding meant that the opposite

If a road looks safe at 40 mph, many  people are going to drive at 40  no matter what the limit. A 'clearly ridiculous' limit may increase that tendency.  One way to control speed is to make it visually less safe, and seem more likely tof contain pedestrians,  bikes, and other things to hit.
This.

There have been several studies into this effect. Used to be a design assumption that clear sightlines in residential estates would keep pedestrian injuries down, as drivers could see them. Reality was that serious injuries were higher, because people drove faster. Wiggly roads without clear sightlines and people drove slower, more cautiously.
<i>Marmite slave</i>

Re: Lowering speed limit to 20mph increases injuries and fatalities
« Reply #7 on: 18 December, 2017, 10:03:42 am »
http://www.20splenty.org/banes-report takes the lack of statistical rigour apart very nicely.

rogerdodge

  • But that was 25 years ago!
Re: Lowering speed limit to 20mph increases injuries and fatalities
« Reply #8 on: 18 December, 2017, 01:46:44 pm »
It seems to me that part of the problem is enfocement. Some of the drivers I talk to only take a speed limit seriously if there are cameras present, and I can't remember seeing those in an urban residential street.
 On the whole I'd rather have cameras and keep good visbility for when I'm crossing the road.


Kim

  • Timelord
    • Fediverse
Re: Lowering speed limit to 20mph increases injuries and fatalities
« Reply #10 on: 18 December, 2017, 01:56:11 pm »
It seems to me that part of the problem is enfocement. Some of the drivers I talk to only take a speed limit seriously if there are cameras present, and I can't remember seeing those in an urban residential street.
On the whole I'd rather have cameras and keep good visbility for when I'm crossing the road.

I'm less fussed about visibility, but as a cyclist I find most of the other forms of traffic calming (speed cushions, chicanes, pedestrian islands) make things significantly more intimidating - if not outright hazardous - as they encourage impatient drivers to bully you out of the way at the resulting pinch points.

Enforcement is key.  Everyone's favourite police officers have been actively ticketing people for breaking 20mph limits, with an emphasis on commercial drivers (on the basis that they spend more time on the roads, and that if all the buses/taxis/vans are sticking to the speed limit, the rest of the traffic will have to too).  We can't have enforcement without the signs and TROs, though, so a period where they're ignored is to be expected.

Re: Lowering speed limit to 20mph increases injuries and fatalities
« Reply #11 on: 18 December, 2017, 03:42:20 pm »
Quote
I'm less fussed about visibility, but as a cyclist I find most of the other forms of traffic calming (speed cushions, chicanes, pedestrian islands) make things significantly more intimidating - if not outright hazardous - as they encourage impatient drivers to bully you out of the way at the resulting pinch points.

Enforcement is key.  Everyone's favourite police officers have been actively ticketing people for breaking 20mph limits, with an emphasis on commercial drivers (on the basis that they spend more time on the roads, and that if all the buses/taxis/vans are sticking to the speed limit, the rest of the traffic will have to too).  We can't have enforcement without the signs and TROs, though, so a period where they're ignored is to be expected.

It's a shame my local police force don't appear to take any interest in enforcement.  There aren't any active policing initiatives taking place in County Durham in relation to speeding or close passes.  However the Council have installed plenty of badly designed 'traffic calming' measures which just tend to create dangerous pinch points or lottery give way scenarios if you're on a bike.
Sunshine approaching from the South.

First time in 1,000 years.

Re: Lowering speed limit to 20mph increases injuries and fatalities
« Reply #12 on: 18 December, 2017, 05:01:00 pm »
Following the links and doing an it of research leads to this

http://driveeastmidlands.blogspot.co.uk/2016/09/how-cyclists-put-their-lives-in-hands.html?m=1

Wow. Pretty unbelievable and only encourages me to think lower speed limits are a good thing.

Elsewhere he explains that every single left leaning person is incapable of original or individual thought, as they haven't grown up from the 6th form. Others, of the right are actually individual, freethinking and a veritable rainbow of diversity...

Woofage

  • Tofu-eating Wokerati
  • Ain't no hooves on my bike.
Re: Lowering speed limit to 20mph increases injuries and fatalities
« Reply #13 on: 18 December, 2017, 05:49:38 pm »
^ don't panic, his dog keeps kept* him on the straight and narrow.

* edit. Looks like the old duffer has snuffed it.
Pen Pusher

citoyen

  • Occasionally rides a bike
Re: Lowering speed limit to 20mph increases injuries and fatalities
« Reply #14 on: 18 December, 2017, 05:56:58 pm »
Wow. Pretty unbelievable and only encourages me to think lower speed limits are a good thing.

That's astonishing. Is it genuine or some kind of weak AI parody of a Daily Mail columnist?

I'm intrigued by his notion of 'essential' road users. But not intrigued enough that I want to engage in any kind of discussion with him... EVER
"The future's all yours, you lousy bicycles."

citoyen

  • Occasionally rides a bike
Re: Lowering speed limit to 20mph increases injuries and fatalities
« Reply #15 on: 18 December, 2017, 05:58:07 pm »
* edit. Looks like the old duffer has snuffed it.

One less 'inessential' idiot on the roads...
"The future's all yours, you lousy bicycles."

benborp

  • benbravoorpapa
Re: Lowering speed limit to 20mph increases injuries and fatalities
« Reply #16 on: 18 December, 2017, 07:06:49 pm »
Keith Peat is dead? Well that will make certain corners of the internet more pleasant.

Various of his troll accounts used to stalk me on YouTube.
A world of bedlam trapped inside a small cyclist.

Woofage

  • Tofu-eating Wokerati
  • Ain't no hooves on my bike.
Re: Lowering speed limit to 20mph increases injuries and fatalities
« Reply #17 on: 18 December, 2017, 08:07:31 pm »
Keith Peat is dead? Well that will make certain corners of the internet more pleasant.
Apparently so.
Pen Pusher

rogerzilla

  • When n+1 gets out of hand
Re: Lowering speed limit to 20mph increases injuries and fatalities
« Reply #18 on: 20 December, 2017, 05:32:12 pm »
To be fair, "hard" traffic calming is dangerous for cyclists as we get squeezed where the road narrows.  And speed cushions are useless since they have absolutely zero effect on cars where the track is wide enough to straddle them cleanly, which is anything from a Golf upwards these days; I bet it's a design consideration for car makers.  They are murder in a Suzuki Jimny, though.
Hard work sometimes pays off in the end, but laziness ALWAYS pays off NOW.

Adam

  • It'll soon be summer
    • Charity ride Durness to Dover 18-25th June 2011
Re: Lowering speed limit to 20mph increases injuries and fatalities
« Reply #19 on: 20 December, 2017, 09:44:24 pm »
What's been ignored is the fact the data showed there were reductions in central Bath, and it was in the outer rural areas that deaths & serious injuries went up. 

What's not been stated is what the speeds involved in the actual incidents had been.  If all the crashes occurred when people were speeding at 40mph+, then the fact the drivers should have been doing 20mph is irrelevant.  Simple physics confirms that at 20 mph, very few people get killed, compared with higher speeds.
“Life is like riding a bicycle. To keep your balance you must keep moving.” -Albert Einstein

Re: Lowering speed limit to 20mph increases injuries and fatalities
« Reply #20 on: 21 December, 2017, 06:11:13 am »
It seems to me that part of the problem is enfocement. Some of the drivers I talk to only take a speed limit seriously if there are cameras present, and I can't remember seeing those in an urban residential street.
 On the whole I'd rather have cameras and keep good visbility for when I'm crossing the road.

In Portsmouth, one of the issues was that the Police were unequivocal from the start that they would NOT be enforcing 20 mph limits

This is a standard from  most Police forces

Mr Larrington

  • A bit ov a lyv wyr by slof standirds
  • Custard Wallah
    • Mr Larrington's Automatic Diary
Re: Lowering speed limit to 20mph increases injuries and fatalities
« Reply #21 on: 21 December, 2017, 09:29:02 am »
They've put in quite a few 20 zones in my bit of E17 which, natch, are totally ignored.  TBH I question the utility of a couple of them, especially the one on Forest Road which, ironically, has one end practically outside the police station.
External Transparent Wall Inspection Operative & Mayor of Mortagne-au-Perche
Satisfying the Bloodlust of the Masses in Peacetime

ian

Re: Lowering speed limit to 20mph increases injuries and fatalities
« Reply #22 on: 21 December, 2017, 10:01:50 am »
What's been ignored is the fact the data showed there were reductions in central Bath, and it was in the outer rural areas that deaths & serious injuries went up. 

What's not been stated is what the speeds involved in the actual incidents had been.  If all the crashes occurred when people were speeding at 40mph+, then the fact the drivers should have been doing 20mph is irrelevant.  Simple physics confirms that at 20 mph, very few people get killed, compared with higher speeds.

The No-to-20 campaigns reiterate a lot of bad science and nonsense (the Croydon one is hilariously sad) – much of it is identical to the crap we got in opposition to a homezone back in the early 2000, so they just cut and paste across the decades. I honestly don't get it, is driving at 20 mph that bad?

citoyen

  • Occasionally rides a bike
Re: Lowering speed limit to 20mph increases injuries and fatalities
« Reply #23 on: 21 December, 2017, 01:12:13 pm »
I drove down through Croydon last week on my way to Ikea and was slightly puzzled by the 20 limit on some roads.

Not a problem though, I just set the car's speed limiter accordingly. Don't think the people stuck behind me appreciated it but fuck them. Speeding up would only have got me to the back end of the next queue quicker.
"The future's all yours, you lousy bicycles."

Re: Lowering speed limit to 20mph increases injuries and fatalities
« Reply #24 on: 21 December, 2017, 01:20:38 pm »
20mph speed humps are pretty vicious, people ignore these at their peril.
Get a bicycle. You will never regret it, if you live- Mark Twain