CityCyclingEdinburgh was launched on the 27th of October 2009 as "an experiment".
IT’S TRUE!
CCE is 14years old!
Well done to ALL posters
It soon became useful and entertaining. There are regular posters, people who add useful info occasionally and plenty more who drop by to watch. That's fine. If you want to add news/comments it's easy to register and become a member.
RULES No personal insults. No swearing.
stickyI'm starting to question what has actually changed.
With you on that @jdanielp.
Frankly, all that's really changed since I started cycling in the eighties is that I've got better at it. Traffic is heavier and less well behaved. A few tins of paint got sloshed around. Some pink chuckies.
all road users are less well behaved
Research into 20mph zones (without traffic calming) show it tends to reduce median and 85th percentile speeds by between 1 and 2 mph.
Not a big change, but enough to reduce the incidence of collisions and severity of injuries by a small amount. Given the low cost of these schemes I think it is a useful, if small, intervention.
That said - the Edinburgh scheme has eaten up quite a bit of political capital, officer time and some cash. Tough call over whether this could have been better invested elsewhere.
Emerging results from a UK-wide study on 20mph zones: http://www.pacts.org.uk/wp-content/uploads/sites/2/20mph-Research-GPS-Analysis-RSGB-Analysts-Conf-Febv1.pdf
Interesting link, even if limited
even if speeds are reduced in Edinburgh it does not mean that accidents are reduced, only their severity when they occur
Surely it increases the probability you will manage to stop short of a vehicle/person and prevent the accident in the first place?
oh possibly.
the out of date stopping distance from the highway code suggest a 10m difference between 20 and 30- reality is not that great
the only way to prove any claim is to carry out a proper statistical analysis- unlikely Edinburgh will ever do this
Research into signs-only 20mph zones is still at an early stage. A major study from London states:
"In general, whilst the signed-only schemes in the UK examined have shown only small reductions in vehicle speeds of 1–2mph, early monitoring indicates that they are achieving a number of positive benefits, including reductions in collisions. However, to confirm these
trends further post-implementation data gathered over a longer period of time will be required."
See: http://www.roadsafetyknowledgecentre.org.uk/downloads/20mph-reportv1.0-FINAL.pdf
The only place the limit is likely to be enforced is Old Dalkeith Road where, mysteriously, there are average speed cameras.
To be devil’s advocate many people may not think the 20 mph is a law that matters; ( for this argument if we consider it as a law that does matter), it may be hard for someone to distinguish a law that matters from one that does not. There is many current laws that a reasonable person may consider does not matter there is many historic laws that a reasonable person may consider should not matter there is laws that most people don’t think matter. I don’t think its cultural to consider the law mattering just because it’s a law. Many MPs possibly don’t either nor officials. To a certain extent not sure most people are on board with the 20 mph if not on board would need constant enforcement even then if was resources to do so not sure would be totally successful unless people are on board. People don’t always obey other laws, if did be no recreational drug use the bread and butter of the prison service a large part of courts and law enforcement work. When the speed limit was changed it may be the council did not really expect people to go 20 but nearer 30 than 40.
It would be unrealistic and setting a higher bar than applied to other legislation to measure success or failure on the basis of people all doing 20mph. It may be that instead of going 37 someone goes 32 so still a success if speeds went down at all it may be a some success. I would agree the political capital used may be the main question as it may be could have used it more effectively elsewhere
The dry stopping distance at 20 possibly has not seen as big improvements as at higher speeds as its half thinking distance at 20 mph. (apart from the few cars with auto brake)
>Research into signs-only 20mph zones is still at an early stage
Well the 2014 study you've linked to was certainly an earlier stage.
>" However, to confirm these trends further post-implementation data gathered over a longer period of time will be required."
from the 2018 Bristol study :
"The study employed a more sophisticated analysis than previous studies of 20mph limits, including using individual speed data from over 36 million vehicle observations and controlling for other factors that might affect changes in traffic speeds"
"There has been a reduction in the number of fatal, serious and slight injuries from road traffic collisions, equating to estimated cost savings of over £15 million per year"
"The above changes in fatalities, serious injuries and slight injuries are marked and align with international evidence that reports that a 1mph average speed reduction in urban areas is associated with a 6.2% reduction in collisions."
Why does the absolute number of accidents even matter though? The fear of being in an accident isn't being a statistic, but the potential damage it causes..
http://eprints.uwe.ac.uk/34851/7/BRITE%20Bristol%2020mph%20limit%20evaluation%20report%20final.pdf
"Some will tell you that they are *forced* to break the law"
Others will argue that it is impractical to obey the law as they'd be staring at the speedo rather than watching the road (pretty sure that was the IAM or AA or RAC gambit, can't remember which).
Pity the poor hardpressed OLAM.
http://roadsafetygb.org.uk/news/when-in-town-slow-down-campaign-asks/
"Transport Scotland figures show 96% of accidents involving pedestrians happen in built-up areas, with most casualties occurring between 4-6pm on weekdays and 1-3pm on weekends."
So now we know exactly when to stay indoors!
A quote from the Bristol Report above......
'In conclusion, there appears to be a trend of reduction in casualties. However, due to the fact that reference periods after the introduction of 20mph speed limits vary among areas, and identifying the denominator was problematic, it was not possible to ascertain if this trend is statistically significant. A potential positive finding is that the monthly rate of casualties seems to have fallen despite the fact that more people report walking and/or cycling in Bristol...'
I have emailed the author directly and asked about how the statistics have been analysed.
I personally don't believe it's possible to attribute a statistically significant reduction in accidents to the reduction in speed to 20mph. Certainly not in Edinburgh.
I can’t get the Bristol 2020 report to open
From first link -
“
However, support has come from unexpected quarters, such as the Freight Transport Association. Chris MacRae, its head of policy for Scotland, said 20mph zones “are proven to improve safety for vulnerable road users… driving at lower speeds can also reduce emissions and fuel usage, which may benefit commercial vehicle operators by reducing fuel costs.”
...
Neil Greig, the Scottish-based policy and research director of IAM RoadSmart, said: “The number of casualties is very low anyway and in most parts of Edinburgh the number of deaths and serious injuries is zero.
“I would support it if the 20mph limit encouraged more people out of their cars to walk and cycle, but I haven’t seen that happen. The real answer is not to rely on just putting up 20mph signs, but to segregate cyclists from other traffic.
“
Or
I would support it if it instantly encouraged more people out of their cars and on to their bikes.
But of course it is a gradual attempt to influence driver speed. Watched them painting a 20 sign in colinton this morning when we were waiting for the colinton contingent of Fietsclub Balerno.
He is right about segregation, he cannot always be wrong. Though hardly anyone died, so that is ok, except if you are one of the fatalities e.g. The young man from Balerno killed prior to PoP starting on the treacherous 40mph kingsnowe non- dual road - pinch points and on road parking make it very dangerous. 20 mph there would be good.
I got a response from one of the authors of the Bristol Study.
Quote
'...No, we didn’t control for regression to the mean when looking at the casualty stats. Our main focus of the study, and where we had the best data, was the speed analysis. We only did a basic descriptive analysis of the casualty data, and would certainly urge caution with inferring causality - although I know a lot of the press coverage focussed on that, based on a Press Association article. Unfortunately the project was quite limited, with 35 researcher days to examine the various data sets, so there is definitely more work that could be done to examine outcomes such as casualties more rigorously. We’re much more confident with the work we did on speed...'
Just as expected. No stats to back up any claims on possible accident reduction
So can we now put to bed all this griping about the 20mph zones?
It certainly suggests the, "I drive fast, but I drive safely," arguments are guff.
The evidence speaks for itself: When drivers are forced to slow down, they kill fewer people.
From the first of stickman's linked articles Nick Cook promising the magic bullet as always. I wonder how he plans to simultaneously remove the 20mph limits while diverting the entire transport budget to filling potholes.
He really is living in Cloud-Tory-land.
Mentions IW and NC replies!
there is no evidence of reduced casualties in Edinburgh!!
No one who knows anything about accident statistics compares a 3 month period with another. Especially while the project is still under construction!!!
minimum 3 years data required
There is a degree of hypocrisy here which is worth discussing. We'd be quick to say "let's wait till we have more data" if the stats had shown a slight increase in KSIs. A better line would be to say "Current data is promising, but not yet conclusive. There are many benefits to lower speed limits, and we will continue to do our best to make Edinburgh a safer place."
there is no data. the police seem to have conveniently not counted all the recent accidents around the city.
having said that everywhere is currently on a downward trend for accidents.
Seems we are currently regressing back to the mean
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