London speed limit survival

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Roadiecambs
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London speed limit survival

Post by Roadiecambs »

Hi all,

I don't want to tempt fate here, but was driving around North London over the weekend and was genuinely shocked that this section of road remained at 40mph:

https://www.google.com/maps/@51.572598, ... 384!8i8192

For context, The Bishop's Avenue in Finchley is one of the wealthiest streets in London with many multimillion pound properties, though it seems many of them are rarely occupied.

https://en.wikipedia.org/wiki/The_Bishops_Avenue

What made the speed limit survival particularly surprising was that, whilst well-aligned, this street has a significant number of parked cars and is almost continually developed both sides, as well as being unclassified. The streets either side of it (e.g. Winnington Road, just to the west), are 30mph, despite similar levels of development.

Can anyone provide any context as to how this has actually survived the recent drive for wholescale cuts in London. Even the roads around Hampstead Heath itself, with no development at all, have been cut to 20mph, so this seems a truly remarkable survival.

In addition, it seems there are even a few pre-Worboys repeaters remaining:
https://www.google.com/maps/@51.5743135 ... 384!8i8192
Herned
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Re: London speed limit survival

Post by Herned »

Roadiecambs wrote: Sun Jul 14, 2019 18:05 Hi all,

I don't want to tempt fate here, but was driving around North London over the weekend and was genuinely shocked that this section of road remained at 40mph:
That is very weird, but my cynical side says:
Roadiecambs wrote: Sun Jul 14, 2019 18:05 The Bishop's Avenue in Finchley is one of the wealthiest streets in London with many multimillion pound properties
might be part of the reason
Al__S
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Re: London speed limit survival

Post by Al__S »

Is that a T junction where every arm has a different speed limit?
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Chris5156
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Re: London speed limit survival

Post by Chris5156 »

Roadiecambs wrote: Sun Jul 14, 2019 18:05Can anyone provide any context as to how this has actually survived the recent drive for wholescale cuts in London. Even the roads around Hampstead Heath itself, with no development at all, have been cut to 20mph, so this seems a truly remarkable survival.
I can't, but I'm familiar with The Bishop's Avenue and I will readily agree that it's bizarre. Of all the suburban roads to carry a 40mph limit this must surely be one of the most unlikely, even decades ago when such things were more common. It's just a residential road, continuously built up and surrounded by other 30 limits. I can't imagine why 40 was ever applied, let alone how it's still there now.

The limit is just one of the many things about that road that's decidedly weird. The houses are big and expensive to the point of being strange - they're too big and too showy - and it never really feels like a place where anyone lives. About a quarter of the properties always seem to have hoardings around them or building works going on at any given time, and a lot of the parked vehicles are construction vans and so on. It really is a whole street of property speculation as a business.
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Berk
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Re: London speed limit survival

Post by Berk »

Perhaps you mean the houses belong to overseas high net-worth individuals. :roll:
Roadiecambs
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Re: London speed limit survival

Post by Roadiecambs »

I agree with your analysis, Chris5156. One can just about imagine that maybe back when the road was originally built (1930s), that there was a rather little development along it, and it was seen as a link between the A1 and Kenwood Park, so possibly 40mph was considered for that reason. But it really is almost impossible to see why it still has that limit now and hasn't been cut to 30mph. I didn't get up to 40mph along its entire distance (though to be fair it was dark when I drove it).

Maybe the fact that most of the houses are unoccupied has helped preserve its status somehow - i.e. there are no residents to campaign for a lower limit, which would be very hard to object to. Apparently even Justin Biber was renting a house on there, maybe he's a secret Sabristi :laugh:

https://www.mansionglobal.com/articles/ ... -row-43276
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Re: London speed limit survival

Post by sydneynick »

Roadiecambs wrote: Mon Jul 15, 2019 09:23 I agree with your analysis, Chris5156. One can just about imagine that maybe back when the road was originally built (1930s), that there was a rather little development along it, and it was seen as a link between the A1 and Kenwood Park, so possibly 40mph was considered for that reason.
That is not the answer, as 40 mph limits were unknown until the late 1950s when they were introduced on quality roads like the Barnet bypass and Watford Way. They were so strange that the 40 was placed in a white square rather than a circle.
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Roadiecambs
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Re: London speed limit survival

Post by Roadiecambs »

sydneynick wrote: Mon Jul 15, 2019 12:29
Roadiecambs wrote: Mon Jul 15, 2019 09:23 I agree with your analysis, Chris5156. One can just about imagine that maybe back when the road was originally built (1930s), that there was a rather little development along it, and it was seen as a link between the A1 and Kenwood Park, so possibly 40mph was considered for that reason.
That is not the answer, as 40 mph limits were unknown until the late 1950s when they were introduced on quality roads like the Barnet bypass and Watford Way. They were so strange that the 40 was placed in a white square rather than a circle.
Mmm yes I had forgotten that the suburban 40mph limit only got going in the 1950s. So would have required a conscious decision to raise to 40mph. I can only think that the density of development wasn't as high in the 1950s, and maybe its status as a link road between the A1 and Kenwood/Hampstead Heath was the rationale. It is truly odd that it has survived though, in some parts of London this would easily be 20mph.

I have always been surprised that Park Lane northbound remains 40mph, but this is even odder...
PaulLothian
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Re: London speed limit survival

Post by PaulLothian »

Certainly traditionally an area for display of wealth. I remember when, as a teenager in the 60s, my father pointed out to me the house in The Bishop's Avenue that had been bought by the later disgraced financier Emil Savundra, for the unimaginable sum of £100,000!
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Re: London speed limit survival

Post by roadtester »

It is quite wide though.

One good reason for having a higher limit is that the houses are so vulgar and unattractive that you don't want your eyeball lingering for too long on any of them.
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Scratchwood
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Re: London speed limit survival

Post by Scratchwood »

Bishop's Avenue is in Barnet, who are far less draconian on speed limits than Camden and the other inner London boroughs. And it is a fairly important link road between Golders Green/Hampstead and the A1/East Finchley too, so presumably Barnet are happy to have traffic flowing freely along it, and not down narrower roads.

I don't think it has that many pedestrians, it's not a major pedestrian route as the houses are low density and there's nothing on the road in terms of shops etc, and with the lack of intersecting roads, there won't be many crossing over either.
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ajuk
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Re: London speed limit survival

Post by ajuk »

Roadiecambs wrote: Mon Jul 15, 2019 09:23 I agree with your analysis, Chris5156. One can just about imagine that maybe back when the road was originally built (1930s), that there was a rather little development along it, and it was seen as a link between the A1 and Kenwood Park, so possibly 40mph was considered for that reason. But it really is almost impossible to see why it still has that limit now and hasn't been cut to 30mph. I didn't get up to 40mph along its entire distance (though to be fair it was dark when I drove it).
I think a lot of generous 40 limits survive simply because the average road speed is so low, often no higher than many 30 limit roads, many of them have lower speeds than 30 limit roads, and compliance is so high the council just don't have an excuse to lower them.
Every time they do a survey they will get something like an average speed of 30mph an 85th percentile speed of 35 and 97% compliance. I've known 20 limit roads have 97% non-compliance. The highest average speed I know of on a 20 limit road is 29mph, that's 3mph faster than the lowest average speed I know on a 40 limit road which is 26mph.
That's the sheer level of discrepancy you get between speed limits set by traffic engineers and speed limits set by the what councilour X says it should be, on the advice of Helen Lovejoy, it's shocking.
People forget that because the engineering standard of a road is primarily what dictates speed, 40 repeaters are there to warn pedestrians of the road danger, they make very little difference to average speed.
Last edited by ajuk on Sat Oct 12, 2019 19:18, edited 1 time in total.
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Re: London speed limit survival

Post by Bryn666 »

Don't use engineering standards as a base - DMRB is so overdesigned that roads you can drive at 70mph on are still only in the 80km/h design speed bracket.

The A555 is a classic example of the horizontal alignment being way overblown and as a result the 50 limit that is applied due to parallel cycleways and at grade junctions is widely ignored.

Put it this way, DMRB tells you that a new build 30 limit road should have a minimum radius of 90m with 7% superelevation. Are we building a town bypass or the bowl at Monza?
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Re: London speed limit survival

Post by KeithW »

Bryn666 wrote: Fri Oct 11, 2019 08:32 Put it this way, DMRB tells you that a new build 30 limit road should have a minimum radius of 90m with 7% superelevation. Are we building a town bypass or the bowl at Monza?
We are building a road that high sided vehicles can go around without toppling over.
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Re: London speed limit survival

Post by fras »

KeithW wrote: Fri Oct 11, 2019 12:32
Bryn666 wrote: Fri Oct 11, 2019 08:32 Put it this way, DMRB tells you that a new build 30 limit road should have a minimum radius of 90m with 7% superelevation. Are we building a town bypass or the bowl at Monza?
We are building a road that high sided vehicles can go around without toppling over.
OK, so how do they manage on roads with lesser radii ? Could it be they have to slow down ? 30 mph is the maximum legal limit, not a target.
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ajuk
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Re: London speed limit survival

Post by ajuk »

Well, I'd like to use the 85th percentile speed as a basis for setting speed limits, that's where you get the over 90% compliance. People on mass do not go faster, even when a road is lined with repeaters telling people they can.
I'd like to be able to say that if exceptions to the 85th rule were kept just that, exceptional, lower speed limits in targeted places would be more effective, but even that doesn't seem to work. Most people continue to drive to the road standard and conditions at the time.

The mean average is what the DfT recommend using now, using average behaviour as a basis for setting prohibitions is a bit strange, but the average speed is normally only about 15% slower than the 85th percentile, that's how uniform most speeds are, so it's not too bad, and there is some evidence that setting a speed limit slightly below engineering standard may improve safety. Although the DfT guideline means you can have the speed limit set as much as 5mph below the mean average, that's already bats, even that quite generous guideline gets ignored and councils put in speed limits that have no basis on traffic speeds, that's when things really start to get dangerous.
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Re: London speed limit survival

Post by Roadiecambs »

It's finally proposed to be reduced to 30mph. Surprised it's not 20....

https://publicnoticeportal.uk/notice/tr ... ab5095bcd0
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Re: London speed limit survival

Post by wallmeerkat »

It's outside of London and NI rules are maybe different, but I'd asked a couple of councillors why the 40mph road through this village: https://www.google.com/maps/@54.4502413 ... ?entry=ttu

shouldn't be 30. You have a crossroads that can be busy at times, housing, a busy convenience store shop, a primary school, a pub/restaurant.

I was informed that because there wasn't enough frontage directly on the road (ie. most of the housing were in developments on streets off the road) that is why it is inapplicable to be 30. Best they could do is a temporary 20mph school time limit, that is routinely ignored by the local Range Rover brigade.
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Re: London speed limit survival

Post by thatapanydude »

Roadiecambs wrote: Thu Jan 18, 2024 22:24 It's finally proposed to be reduced to 30mph. Surprised it's not 20....

https://publicnoticeportal.uk/notice/tr ... ab5095bcd0
20mph would have been far too slow! Though 40mph (unless at night) is not even possible very much as there are a lot of parked cars about!
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Re: London speed limit survival

Post by Truvelo »

Looks as though the 40mph limit was introduced in 1965.
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