Safe Speed Forums

What's the difference between a 20 mph limit and a 20mph zone in enforcement terms?

Manchester have just made a sizeable area of the city centre a 20mph zone without any self enforcement furniture. Could this limit be enforced by a safety van?

Which is fine where mean speeds are below 24mph



The whole point of 20mph zones is that they are self-enforcing.

I posed this question in another post. From reading in here --speedos are not calibrated below 25 = 20+10 %(2)+2 = 24 -so how can they justify charges when the industry standard is above the threshold

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lets bring sanity back to speed limits.
Drivers are like donkeys -they respond best to a carrot, not a stick .Road safety experts are like Asses - best kept covered up ,or sat on

At peak times there's absolutely no way you could get to much more than 20mph and it is a perfectly sensible limit given the high number of pedestrians / cycles / etc...

I regularly drive through the city at night when there is absolutely no-one about and there are some really long straight sections of road which would fall nicely within the criteria for mobile enforcement given that no-one would stick to it?

BUT - are speedos required BY LAW to be accurate below 25 MPH-

ARGUE ALL THE OTHER THINGS, BUT COME BACK TO THIS ONE POINT-

IF requirement is above 24,/25 , then THE LAW AGIN IS AN ASS -END OF STORY.

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lets bring sanity back to speed limits.
Drivers are like donkeys -they respond best to a carrot, not a stick .Road safety experts are like Asses - best kept covered up ,or sat on

I think you're missing the point.

If the limit is self enforcing, and mean speeds are below 24mph, why would the limit be enforced by cameras?

Depends where they take the measurements I suppose. Some parts will have mean speeds in the single figure range, others considerably more than 20. Given the size of the area and the number of roads it encompasses, it would be difficult to get an accurate measurement of the mean speed across the entire zone.

The limit is not self enforcing either (I presume by that you mean with speedhumps or similar devices?)

Gents - i hear you - but if the device you need to rely on to keep you from a prosequetion is not designed to be accurate at that speed - can they do you - argue all you wan about the other bits - first find out the spec of a speedo.

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lets bring sanity back to speed limits.
Drivers are like donkeys -they respond best to a carrot, not a stick .Road safety experts are like Asses - best kept covered up ,or sat on

Maybe they wouldn't prosecute at 24? Maybe it'd be something like 28? What's the threshold for the ones enforcing the bridges in London?

True



I mean its self enforcing in the sense that mean speeds are below 24mph - either due to pre-existing conditions, or due to traffic calming measures.

The whole point is that there is no need to prosecute anyone

If there's no need to prosecute, and the mean speed is already below 24mph, what exactly is the point?

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

To bring limits into line so they are consistant with the road environment and with each other.

Whats the problem?

Actually the problem really is that it's a game of 'let's pretend' played with the law. Let's pretend that the speed limit has a large role to play in road safety. Let's pretend that drivers will obey the speed limit. Let's pretend that road safety is 'simple physics'.

But playing 'let's pretend' with the law is a dangerous game. As the law sinks into greater and greater disrepute necessary laws (and broader respect for authority) are also tarnished.

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

I thought Safe Speed was for limits which are set consitantly with each other and with the circumstances?

You bet. That excludes 20mph speed limits that appeal to social engineers!

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

The road conditions in any city centre vary greatly depending on time of day and day of the week. The mean speed is probably well below 24 mph due to frequent daytime congestion, but on the other hand, in Manchester City Centre there are a number of roads such as Whitworth Street where, at quieter times, 30 mph is a perfectly reasonable speed. To impose a blanket limit in such an area is an unreasonable dumbing-down, and it would be an outrage if the limit was to be enforced by Talivans when traffic is free-flowing.

20 mph limits, if used at all, should be reserved for small residential streets and narrow, crowded central shopping areas, not wide, straight city roads.

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"Show me someone who says that they have never exceeded a speed limit, and I'll show you a liar, or a menace." (Austin Williams - Director, Transport Research Group)

Any views expressed in this post are personal opinions and may not represent the views of Safe Speed

On what is that statement based?

Or indeed any road



Again, as per my point in the other thread, the limit is simply a line in the sand. Its not an attempt to define the current safe speed or the maximum safe speed - rather it is a line in the sand drawn such that exceeding the limit is likely to result in an unacceptable level of risk.

It's a quip based on a series of false priorities that I perceive.

- social and ideological values dressed up as safety values
- anti-car policies dressed up as safety policies
- road safety values governed by dogma rather than sound science
- excessive trust in the number; insufficient trust in responsible behaviour.

I see little or no value in 20mph speed limits because controlling speed to ~ 20mph actually takes far too much driver attention. This, of course, is why DfT says that 20mph zones should be 'self enforcing'. I think we could usefully have 'slow zones' or something like that, but the number is just a serious bloody distraction. The fact that it carries the force of law makes the distraction worse. And the gloss of legitimacy makes 20mph a wholly illegitimate target for many.

In lots of 20mph zones, 20mph will still be murderously fast (from time to time). If 20mph (or 30mph or 70mph) can frequently be murderously fast, what will save us? What does save us? It can only be appropriate behaviour. Let's have more appropriate behaviour please. Let's have policies that value appropriate behaviour.

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety