Borough wide 20 mph limit planned - allegedly

[Tim Lund]

According to 'Living Streets', Lewisham is one of three London boroughs now planning a general 20 mph speed limit, and I also heard this from Cllr Paschoud at a recent meeting of the Perry Vale ward co-ordinators' group.



Here is more about it on the Living Streets web site.

Like most transport issues, it gets very technical, as well as stirring up all sorts of tribal feelings, so it's worth saying that it would not apply to main roads which come under the control of Transport for London. The actual change proposed is, I believe, more a matter of changing the rules, so that the Council doesn't have to spend so much money putting up repeater signs for 20 mph zones (and spoiling the view), as it has to currently on the many 20 mph zones that already exist.

I've tried and failed to find anything about it on the Lewisham web site, and googling "Lewisham speed limit" takes you to some grandstanding from Green councillor Darren Johnson saying Lewisham is rejecting this proposal.

So, subject to more details being forthcoming, I say well done Lewisham, and I hope other readers of this Forum will contact their councillors to say the same.

[marymck]

Oh gosh, more air pollution and speed bumps, I suppose. The air quality has become shocking on upper kirkdale since the combination of speed bumps, new build housing with inadequate parking and the changes to the junction with thorpwood which has decanted more parked cars onto this part of the road. Traffic is so slow now as it can only pass the bottleneck of parked cars one at a time. It's choking sometimes walking past and the fumes get inside the houses.

But I guess Lewisham will just impose it on us in the same way as the allegedly cancer causing new street flood lighting.

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[Tim Lund]

Mary - I think that speed bumps are, like repeater signs, the sort of thing they want to avoid / save money on. The point is to change driver behaviour so that on residential roads, 20 mph becomes the norm, so no accelerating and decelerating between whatever speed you take a bump at and 30 mph between.

Any they do also want to save lives - don't forget that.

[marymck]

It would be interesting to know how many lives are saved by 20mph zones compared with how many are lost to air pollution. And how air pollution compares in those borough with high proportions of 20mph zones, compared with those borough that don't have them. Engines don't work efficiently at that speed and I'd hate other residents to suffer the same way as we are, since the changes I mentioned above.

I'm dreading the switching on of the two white street lights that have been installed outside my bedroom window. LBL will have achieved a pollution hat trick in under a year: noise from the speed bumps, lung damage from the traffic jams, and melatonin suppression from white light.

They really need to think of the long term damage this pollution is doing to our children and factor in the effects of the increase in air pollution, before taking a decision on 20mph zones.

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[Tim Lund]

It would be interesting to know how many lives are saved by 20mph zones compared with how many are lost to air pollution.

Yes - that is a quantifiable question, although you'd need to compare it with how many lives lost to the additional air pollution thanks to the change in driver behaviour, which will be rather less.

On the matter of car fuel efficiency and speed, here's a chart



Source here

Doesn't look as if there's much difference between 20 & 30 mph, so a general 20 mph limit should not be much of a problem.

I'll ask Cllr Paschoud if he can answer this question, properly formulated. He's someone who can handle numbers, and see what estimate I can come up with.

[marymck]

Thanks Tim.

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[chrisj1948]

Most cars are marginally less polluting at 30 mph rather than 20mph. However a 20mph limit should tend to reduce braking/acceleration cycles; which do generate significant pollution.

I am in favour of 20mph limits on urban residential roads. Statistics indicate that they reduce the number of serious accidents, and to a certain degree return the roads to the residents since pedestrians, cyclists and children are at less risk.

Regards
Chris

[hairybuddha]

Excellent news and something that I would strongly support.

Lots of good info including a comprehensive mythbusting section here: http://www.20splentyforus.org.uk/index.htm (although they could really do with getting a good web designer in).

Obvious health warning: They can't exactly be accused of impartiality, though they do back up their opinions with a strong evidence base.

More than the safety issue, I would support 20mph limits as a quality of life/quality of public space issue. Speeding cars are a real problem - at least outside of rush hour - and make walking around certain bits of town unbearable.

[Likelife]

I'm confused. That map you posted shows Camden, Harringey and Southwark as planning to have 20mph. Lewisham is showed as more than 25%...

[Tim Lund]

I'm confused. That map you posted shows Camden, Harringey and Southwark as planning to have 20mph. Lewisham is showed as more than 25%...

Yes - seems I'd gone into a time warp back to my transport activist days when I lived in Southwark. It would explain the lack of anything on the Lewisham web site at the moment. But Cllr Paschoud was talking about it, so hopefully on its way.

[hairybuddha]

I'm confused. That map you posted shows Camden, Harringey and Southwark as planning to have 20mph. Lewisham is showed as more than 25%...

Yes - seems I'd gone into a time warp back to my transport activist days when I lived in Southwark. It would explain the lack of anything on the Lewisham web site at the moment. But Cllr Paschoud was talking about it, so hopefully on its way.

You are right that it is being considered though. Here is the Lewisham JSNA doc which sets out a lot of the thinking and evidence: http://t.co/LW1WoFXQmz

[Tim Lund]

Much obliged, HB

[Likelife]

I'm confused. That map you posted shows Camden, Harringey and Southwark as planning to have 20mph. Lewisham is showed as more than 25%...

Yes - seems I'd gone into a time warp back to my transport activist days when I lived in Southwark. It would explain the lack of anything on the Lewisham web site at the moment. But Cllr Paschoud was talking about it, so hopefully on its way.

Ahhh that's makes sense! A 20mph speed limit just is not practical on some roads in Lewisham compared to the roads in Islington. Would roads like Bromley Road and Brockley Rise be included or would TfL have to give the go ahead as they manage A roads?

[Eagle]

As far as I am aware ( and that is not a great deal ) I believe Lewisham would NOT be responsible for Tfl roads or trunk roads like the glorious south circular.

I would support a 20mph limit if I could be sure it was properly enforced. I have no confidence it would be at present

[marymck]

Another reason for the massively increased amount of traffic on upper kirkdale is the ridiculous time it now takes to get along Dartmouth road. Those pinch points that hold up the traffic there can't be doing much good to residents health there either. Buses have to take turns to pass. I've just spent a record time on the 176 in Dartmouth road. At this rate I won't get to town before the shops close!

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[perryman]

In which roads do the majority of accidents happen,
(where a reduction in speed could significantly reduce the resultant injuries and destruction)?

I'm guessing the speed of traffic on the residential roads is not the main problem.
I'm pretty certain Cllr Paschoud of Perry Vale Ward has no intention of introducing a 20 mph speed limit in Perry Vale itself,
despite it being mostly residential, has a primary school and is a major pedestrian route for FH Boys secondary school.
So this initiative is deliberately missing the point, much like speed cushions that cars do not have to slow for.

As far as efficiency goes - yes, lets maximise the safe throughput of traffic on Lewisham roads.
We all want that surely?
If cars travel at the full breaking distance from the car in front, the optimum speed for cars is just 12 mph.
(Any faster and the increase in breaking distance out weighs any other consideration).
Bring it on!!

[hairybuddha]

I'm glad Mary chose the bus to get to town - If only a few more people were as considerate then the buses would fairly whip along Dartmouth, pinch points and all.

Pinch points and 20mph zones don't create traffic, people in cars do.

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[Eagle]

Well said HB. You write a lot of sense on this subject.

Sydenham's Victorian streets with many railway lines to cross will never make a car friendly place.

As soon as the residents appreciate that and ditch their eco unfriendly vehicles the better. Life in Sydenham would be much nicer.

[marymck]

Actually eagle, I nearly always get the bus to town, because it's cheaper than the train. I don't know if eagle was on the same bus I was, but the problem that caused today's delay was, as often, a Mexican stand off between a succession of buses. No cars involved and problem solved once they'd shunted themselves round the pinch points that caused the problem/delay

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[maestro]

It seems that's the "people in cars create all the traffic problems" tripe torpedoed then.