The 20mph campaign/s and arguments...

Interesting difference of how we both interpret freedom. I think freedom is more important than anything, the only sure thing that is "bad" is tyrannical nanny state making rules for everything. If something is just a little bit more risky, but is a pretty safe freedom to allow the populace, then allow it! I am always going to sway towards less rules even if it means that some bad things happen sometimes. "The man" choking the average person by removing simple freedoms like being allowed to do 30mph through town when the roads are clear, is too much of a step towards nanny state hell (if we are not there already).

I would draw a parallel between 20mph limit to mandatory helmet laws.

Although I fundamentally disagree with you, and there are flaws to your argument (as ncjilee has pointed out - and many others could), you'd probably be interested in this (if you are not already aware of it): Anarchy, State and Utopia: Amazon.co.uk: Robert Nozick: Books

Is their a "For Dummies" version?

Being a treatise on the superiority of libertarian values, I think it qualifies as it is.

#Bkbrn

Bookburn?

It worked for the churches, maybe it'll work for speed limits.

There's a road called Mays Lane near where my mum lives in High Barnet, that's a long stretch with a 20mph limit. It used to have speedbumps but corrupt petrolhead woman-beating mayor Brian Coleman ripped them (and all the cycle lanes in the entire borough) out. It does however have those signs that light up to remind you if you are exceeding the 20mph limit.

Pretty much everyone drives at least 30mph. You'll get beeped at, tailgated and aggressively overtaken if you try to drive at 20mph.

How do we deal with this shit?

Bookburn?

Just in case: It was a serious recommendation. One of the most important books of the 20th century.

There's a road called Mays Lane near where my mum lives in High Barnet, that's a long stretch with a 20mph limit. It used to have speedbumps but corrupt petrolhead woman-beating mayor Brian Coleman ripped them (and all the cycle lanes in the entire borough) out. It does however have those signs that light up to remind you if you are exceeding the 20mph limit.

Pretty much everyone drives at least 30mph. You'll get beeped at, tailgated and aggressively overtaken if you try to drive at 20mph.

How do we deal with this shit?

Get the figures for accidents pre and post bump removal?

Pretty much everyone drives at least 30mph. You'll get beeped at, tailgated and aggressively overtaken if you try to drive at 20mph.

How do we deal with this shit?

Accept that there is no real justification for the artificially low 20 limit and that the right speed for that road is 30?

Ignoring the fact that 20 is clearly safer than 30, 20mph in a car is very slow and there needs to be a reason for a 20mph limit otherwise drivers will just ignore it.

A lot of roads have speed limits that are all other the place in this country and while it is easy to say towns and cities should be 20 when you look further a field you see how mad some of the limits are and wonder where they came from. I live in the New Forest and there are roads with a 40mph limit that are single lane, no pavement, twisty turn affairs where even driving at 20 would not be sensible. There won't be many accidents as nobody to hit but the logic still seems odd to think you can legally drive down those sort of roads at 40.

What is the rational behind a 20mph limit in your High Barnett example?

From what I remember working in Transportation at the City Council, speed limits are set by the police rather than anyone else, and there is neat table (which I can't find) that sets out how low you can enforce a limit in relation to the amount of people injured/killed in accidents in the preceding 12 months. This all requires an order signed by the secretary of state for transport as well, so they don't just change them on the fly.
I think the majority of deaths that cause the speed limits are of drivers and passengers rather than pedestrians (or cyclists).
So there should be (theoretically) no 'artificially low' speed limits, just bad drivers/poorly designed roads.

The DfT has made it easier for local authorities to set a local speed limit as is happening in many London boroughs

Ah, cutting red tape! Excellent.

Ignoring the fact that 20 is clearly safer than 30

Not on a motorway :-)

I would imagine that RTA casualty rates cannot be the only criteria by which 20mph limits are imposed. After all, if they were you would have to have proved that deaths or injuries were caused specifically by going between 21mph and 30mph, and not more or less, or your tinkering will have no benefit.

The vast majority of streets are of course engineered to be safe at 30mph, as it has been the urban speed limit since our great grandfathers' times. This is why on the face of it there is very little justification for lower limits on safety grounds alone, and why 20mph zones require additional hazards to artificially lower traffic speeds.

Therefore it's got to be things like noise levels, air quality, the numbers and types of other road users, proximity of schools, shops, traffic volume etc. That would be how 20mph zones are currently mapped out.

On the point of roads being enginered to be safe at 30". Safe for who? Safe for drivers meaning less likely to crash into a tree, or protected by barriers, or seperated from walkers by railings may mean less safe for people outside the protection of the chasis and airbags...

If I get given a street and am told it has a 20mph limit that affects all the junction radiuses (corner angles). I can tighten everything up, it means I can have areas where cars and pedestrians and cyclists negotiate for space, it changes the whole rules of the game.

If it's 30mph I’m going to have to control everything, I’m going to have to have signalised junctions, I’m going to have to illuminate everywhere and I’m going to have to put in radiuses that refuse vehicles can take at 30mph because that’s the design speed of the road. All these things that people don’t like about a street environment is about having to design for 30mph, which means we have to protect people from it.

from here

Brighton went to 20mph for most of the city center a while ago. Of course most people ignore it.

However its the same lot who ignored the 30mph but they don't drive around at 40mph any more. So the 20mph actually means that the majority stay under 30mph even if they are 'breaking the law'.

Traffic has got a lot safer since then.

Good news:

http://www.20splentyforus.org.uk/Press_Releases/City_of_London_Agree_Total_20mph_Limits.pdf

Riding through Islington and Camden, where 20mph limits are increasingly common, I've come to the conclusion that they're almost entirely useless without enforcement. Since there is no enforcement, they're useless.

I don't think it's any exaggeration to say that the majority of motorists, regardless of vehicle type or who's driving, treat them as nothing more than advisory.

Are any (other) boroughs already 20 zones? If so, which? It would be great to see the inner-boroughs, at the very least, adopt it.

Of course, much as 20mph has proven benefits even without enforcement, it of course becomes better with it. There used to be a vicious circle, though. Whenever someone wanted 20mph somewhere, the police would say 'ah, but we wouldn't enforce it'. The authorities would then say 'ah, OK, so then let's not do it' (which is why we've been dragging our feet over it for so long). The more 20mph limits there are, the more untenable the position of the police becomes.

Also, even without enforcement, should someone who was driving too fast be implicated in a crash, that would count against them. (Obviously, it's better to prevent crashes rather than count on such post-crash factors, but 20mph does that, too.)

Are any (other) boroughs already 20 zones? If so, which? It would be great to see the inner-boroughs, at the very least, adopt it.

Southwark, Camden, Islington, and Hackney, to varying degrees (e.g., which main streets are included) and with different methods (zones or limits).

http://www.standard.co.uk/news/transport/camden-joins-islington-and-southwark-to-cut-road-speed-limits-to-20mph-8389053.html

Also, usefully, the City Police have said they intend to enforce...

Ah, yes, I missed that small detail. :)