A523 Poynton - New "shared space" junction

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Helvellyn
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Re: A523 Poynton - New "shared space" junction

Post by Helvellyn »

chris486 wrote:
PeterA5145 wrote: That seems to be the inevitable result of using paving on any kind of well-trafficked road. You have to wonder why designers continue doing it :roll:
Exactly - somewhere back on this thread somebody commented that this would be fine if they'd put the bypass in first and this was going through my mind as I went through the junction mid morning today.
If they'd put the bypass in first there wouldn't have been enough of a justification for spending money on Poynton. I get the impression that this was a "we're not getting a bypass any time soon, so what can we do with what we're stuck with" scheme.
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Re: A523 Poynton - New "shared space" junction

Post by chris486 »

At the moment these roundabouts are still better than those pigging traffic lights but my money is on this being swiftly tarmacked over once a pedestrian has tripped on one of the dislodged slabs.

I don't think you need any great field of expertise foresee the vicious cycle once the slabs start cracking - water ingress - frost - repeat.

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Poynton Village (A523) by EthelRedThePetrolHead, on Flickr
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Re: A523 Poynton - New "shared space" junction

Post by Fenlander »

Based on my own observations, paving blocks freeze quicker than Tarmac, is there any truth in my belief or is it just coincidence that (amongst others) the approaches to my old estate were usually only icy on the paved sections and not the blackstuff?
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Re: A523 Poynton - New "shared space" junction

Post by benhb »

Some information about Fountain Place and Park Lane, Poynton Town Centre...

The bypass was, and continues to be, a very very long-term possibility for Poynton. In 2008, urgent measures were necessary if the retail centre of the town was to be saved. There was no point in sitting around vaguely hoping a by-pass might, one day, be built.

The main junction, Fountain Place, has to be able to withstand huge impact loads from the volume of traffic. This includes LOTS of 44 ton HGV's with trailers turning through 90 degrees. Even high quality tarmac buckles under these sorts of loads. The middle of the junction is therefore paved with deep granite setts, set on a very strong sub-base and very carefully detailed so that the loads are widely dispersed. To date, the main paving in the two circles is holding up well.

Setts can be more durable, robust, and suited to heavy traffic loads than bitumen. BUT they must be very carefully detailed and constructed. Belgium, Denmark, Germany, Sweden, The Netherlands etc all use setts and blocks extensively. The problem is that the UK has lost the skills necessary to lay them properly.

During the design of Phase 2 of the Poynton scheme, Cheshire East Highways made a political decision to bring all engineering work back in house. I was given the (unwelcome) instruction to dismiss our excellent consultant engineer. :confused: I agreed on the basis that all engineering construction drawings be sent to me for checking BEFORE they were issued to the contractor.

In the event, no drawings were sent to my office. During construction, our team were surprsied and alarmed to see the contractor laying sets without any of the essential support or correct detailing. We were then shown a shoddy drawing produced by Cheshire East (unseen by us until then). This demonstrated zero knowledge of basic engineering good practice, or of basic physics! If an engineering student had produced such a drawing during HNC Year One, I would have advised switching training to beautician or hairdressing... Cheshire East's in-house team detailed the drainage gullies and approach ramps on London Road and Chester Road. These have, predictably, all failed and must now be replaced at considerable expense.

Moral: get the right people to design and construct your roads, and they won't fail.
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Re: A523 Poynton - New "shared space" junction

Post by Helvellyn »

I think you're preaching to the converted there!
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Re: A523 Poynton - New "shared space" junction

Post by Bryn666 »

Similar debates raging in Blackburn regarding rigid vs flexible surfacing and heavy traffic.

We do seem to have a culture nationally of whatever is cheapest wins regardless of suitability, longevity, or quality. Then you get political decisions that make the above even worse.
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Re: A523 Poynton - New "shared space" junction

Post by A303Chris »

Bryn666 wrote:Similar debates raging in Blackburn regarding rigid vs flexible surfacing and heavy traffic.

We do seem to have a culture nationally of whatever is cheapest wins regardless of suitability, longevity, or quality. Then you get political decisions that make the above even worse.

We've all been there. One authority I worked for, I will not name, pedestrianised one road and then made another dual carriageway to take the extra flows. During the design I stated that the existing carriageway which was to become one side of the dual carriageway needed full reconstruction especially as deflectograph surveys showed failure of the sub base and capping layer. I was told the rigid construction was fine and a plane and resurface was all that was needed, so that costs were kept down. Again I stated that with the increased loads the road would not last. I was overruled told not to go to committee and my senior officer who had no highway experience went to committee about how they had kept the costs down, The substandard design was approved and I changed jobs about a year afterwards. Within 3 years of completion there was a total failure of the road, which the local authority put down to poor workmanship, how I laughed.
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Re: A523 Poynton - New "shared space" junction

Post by kevjs »

Bryn666 wrote:Similar debates raging in Blackburn regarding rigid vs flexible surfacing and heavy traffic.

We do seem to have a culture nationally of whatever is cheapest wins regardless of suitability, longevity, or quality. Then you get political decisions that make the above even worse.
Sounds like some of the faux-pedestrianisation in Nottingham - they've not even finished the works (which have been a series of projects over about the last three/four years) and the paving stones/bricks on the original sections are already becoming really uneven and cracked, especially where lorries park to load on the pavements and it looks a mess - especially so when wet and the street lighting is on which highlights the faults even more
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Re: A523 Poynton - New "shared space" junction

Post by tggzzz »

In his post on 15th Jan, benhb makes some points with which I have considerable professional sympathy. He also notes:
benhb wrote: Setts can be more durable, robust, and suited to heavy traffic loads than bitumen. BUT they must be very carefully detailed and constructed. ... The problem is that the UK has lost the skills necessary to lay them properly.
Consider the case when, not if, a utility company digs up the surface in order to make repairs or improvements to their services.

Question 1a: are the utility company required to return the surface to its original state (e.g. especially pretty tarmac, blocks and setts) or do they "merely" have to make it suitable for vehicles and pedestrians (e.g. bog-standard black tarmac)?

Question 1b: what period can elapse before the work is completed?

Question 2a: will their gangs have sufficient expertise to correctly reinstate special surfaces?

Question 2b: if not, what is a plausible outcome?

It would be a great shame if Poynton ended up feeling and looking as messy as the area outside the Bristol Hippodrome, viz:
https://maps.google.co.uk/?ll=51.452862 ... 3,,0,11.74
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Re: A523 Poynton - New "shared space" junction

Post by tggzzz »

Derek wrote:I know as a driver that I naturally drive more carefully when the road looks dangerous...
That's my reaction and the reaction of most drivers - but not all.

It relies on all these conditions being met:
  • 1: seeing that it isn't normal, and/or seeing vehicles behaving unexpectedly
    2: recognising that danger
    3: reacting correctly and slowing down
Unfortunately we've all seen many examples where those conditions aren't true, either because the driver is not paying proper attention:
  • driver adjusting audio system
    driver chatting to passengers
    driver cellphone
    poor visibility in bad weather or at night
or, worse and more culpably, because the driver is reckless:
  • driver is drunk
    driver is deliberately being reckless due to excess testosterone or showing off
    driver just inexplicably stupid
Now we probably can't do much about the deliverately reckless drivers.

But shouldn't we have sufficient conventional hints that will catch the eye of inattentive drivers? I'm thinking of the things to which their eyes are already attuned, and are therefore more likely to be recognised out of the corner of their eye. One classic example is that drivers are attuned to seeing solid white lines indicating they must stop. It is comparatively difficult to notice that a line is absent(!). Merely changing the road surface is insufficient, since there are so many such changes that are correctly completely ignored.

Portishead is a good example of that. It was unpleasant when the traffic lights were first removed, but is perfectly pleasant now that white "give way" lines have been repainted.

Of course, in environments where shared spaces are commonplace eyes will already be attuned. But we live in the UK, and should act accordingly - at least until shared spaces are commonplace.
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Re: A523 Poynton - New "shared space" junction

Post by benhb »

How would you define Portishead's Cabstand as "pleasant" or "unpleasant". For whom?

If you're concerns about shared space were correct, we should be seeing worse accident statistics in shared space areas. This does not seem to be the case - it is still two early, after two years' operation, to fully assess Poynton Town Centre's accident improvements, but the reports look pretty positive so far... Maybe drivers really are more intelligent and responsible than we tend to assume?
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Re: A523 Poynton - New "shared space" junction

Post by PeterA5145 »

Derek wrote:I know as a driver that I naturally drive more carefully when the road looks dangerous...
In general, safe-looking roads are safe, and dangerous-looking roads are dangerous.

Yes, there may be a reaction of increased caution on encountering an unfamiliar layout, but familiarity rapidly breeds contempt.

I would say that, as a broad principle, safe roads are clear, consistent, predictable, have good sightlines and minimise potential conflicts between different traffic streams and different classes of road users. Safe roads are self-explaining and encourage responsible behaviour. This may well be (indeed probably is) the case at Poynton, but that doesn't mean that confronting road users with the unfamiliar inevitably improves safety.
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Re: A523 Poynton - New "shared space" junction

Post by Helvellyn »

Could you end up with a design like this that results in more low-speed shunts with no serious consequences but fewer more serious accidents?
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Re: A523 Poynton - New "shared space" junction

Post by tggzzz »

benhb wrote:How would you define Portishead's Cabstand as "pleasant" or "unpleasant". For whom?
I don't know what the "cabstand" is. My apologies for not being sufficiently explicit; I was referring to driving through the A369/B3124 junction, which is perfectly fine after white stop lines were painted to replace the removed traffic lights. I have no other opinion about Portishead.
benhb wrote:If you're concerns about shared space were correct, we should be seeing worse accident statistics in shared space areas. This does not seem to be the case - it is still two early, after two years' operation, to fully assess Poynton Town Centre's accident improvements, but the reports look pretty positive so far... Maybe drivers really are more intelligent and responsible than we tend to assume?
Several problems...

Firstly we are talking about the statistics of small numbers which inevitably are subject to large variability. That precludes drawing any valid conclusions - not that that would stop politicians! (To make the abstract more concrete, consider a fictional pretty safe location that had one accident in the past decade. If there are no accidents within two years of a change, what can be concluded? Only that the change probably hasn't made it radically more dangerous, which is pretty uninteresting).

Secondly there is the possibility that a change increases the number of minor accidents that aren't reported to the police, or where the police quite reasonably don't take any action. To make the abstract more concrete, consider the anecdote about Poynton in the last three paragraphs of http://www.urbanmovement.co.uk/2/post/2 ... davey.html. FWIW I think that note is balanced, nuanced and I have no strong disagreements with its statements.

Thirdly, there's a standard "Human Factors" phenomenon: completely consistent is safe, completely inconsistent is also safe, but mostly consistent is unsafe. Why? Because people naturally come to rely on what they experience frequently, and get caught out by the unexpected inconsistency. In an ideal world everybody is always alert and responsible and would spot the occasional inconsistency. But we live on Planet Earth, not Planet Utopia, and should act accordingly.

PeterA5145 made a very similar point, and he is correct.

Do you have any comments about my questions w.r.t. utilities digging up and repairing setts, blocks and pretty tarmac?
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Re: A523 Poynton - New "shared space" junction

Post by tggzzz »

Helvellyn wrote:Could you end up with a design like this that results in more low-speed shunts with no serious consequences but fewer more serious accidents?
That's a very interesting question, and one which I think will remain unanswered unless you have access to insurance companies' databases.

The trouble is that people and the police won't bother to record such accidents. People will be significantly incovenienced, their insurance premiums will increase (as will those of people living nearby). The statistics will appear better.
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Re: A523 Poynton - New "shared space" junction

Post by darkcape »

tggzzz wrote:

Question 1a: are the utility company required to return the surface to its original state (e.g. especially pretty tarmac, blocks and setts) or do they "merely" have to make it suitable for vehicles and pedestrians (e.g. bog-standard black tarmac)?

Question 1b: what period can elapse before the work is completed?

Question 2a: will their gangs have sufficient expertise to correctly reinstate special surfaces?

Question 2b: if not, what is a plausible outcome?
RE 1a: From recent experience it depends on two factors: The competence of the highway authority responsible for the highway undergoing the works, and the desire/capability of the contractor to do a good job. Example: Last year we did a load of streetworks up north, and at the time no formal agreement was made on reinstatement terms. We agreed informally that we would reinstate to match the existing surface with whatever we could remove and re-lay. When it came to reinstating a new area (for example, where we had removed street furniture from the footway leaving a gap in the paving), the council could not provide us with their stock of matching paving, so we reinstated with concrete or tarmac. The council then changed their mind and asked to reinstate to match the existing, which although we were not contractually obliged to do we did to satisfy the client.

However, other local authorities have been happy for us to whack tarmac in whatever works we have made regardless of what the existing is. Recently we were in Essex and the company director joined us, meaning we reinstated to match at each location.

I wouldn't have thought that laying block paving or slabs is a 'specialist' skill, it's just laziness of contractors/highway authorities in not ensuring the job is done correctly. It's no surprise that the footway paving is shot to bits when we excavate to find it on 300mm of ballast.
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Re: A523 Poynton - New "shared space" junction

Post by tggzzz »

darkcape wrote: ... The competence of the highway authority responsible for the highway undergoing the works, and the desire/capability of the contractor to do a good job...
Plausible but not comforting. I imagine budgetary constraints will also be a significant consideration - and I can't see that constraint relaxing!
darkcape wrote:I wouldn't have thought that laying block paving or slabs is a 'specialist' skill,
I wouldn't have either, so I was surprised and concerned by Ben Hamilton-Baillie's statement on Wed Jan 15, 2014 10:32 that:
benhb wrote:Setts can be more durable, robust, and suited to heavy traffic loads than bitumen. BUT they must be very carefully detailed and constructed. ... The problem is that the UK has lost the skills necessary to lay them properly.
As I've noted previously, I've considerable professional sympathy with Ben's statements in that note. As a matter of principle, I would be mildly curious to hear other parties' positions. None of which has any bearing on the questions I asked about utilities reinstating surfaces, of course.
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Re: A523 Poynton - New "shared space" junction

Post by benhb »

Talk on Poynton and its engineering to be hosted by "The Engineering Club". Wednesday, 19 March, 6 pm.
The Building Centre, London. The event is free
Attachments
Cross Town Traffic .pdf
Event details
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Re: A523 Poynton - New "shared space" junction

Post by boing_uk »

I have to say that I am a massive fan of shared space. The problem I have, professionally, is proving that it works.

Poynton is, IMO, a scheme that does the job perfectly for such a busy intersection.

The difficulty is convincing the higher-ups, the councillors and the safety professionals that it is a suitable application. The arguments I have already heard are "well drivers round here..."

And not forgetting the debacles in Blackpool and now in Grimsby. Both of which are, in my own opinion, poorly executed examples (or at least, examples which could and should have been executed a lot better).

It would help a great deal if such schemes were publicised in promotional roadshows, or with some review by one of the Institutions that doesn't come across as a sales-pitch for BHB or Martin Cassini.

As an engineer, I DESPERATELY need evidence to make a concerted and peer-reviewed argument for the installation of shared space in order to win over the traditionalists.

Certainly in my area, change is frowned upon. Just changing a separately signalised right turn to a gap accepting one caused such local controversy, one would think I had ordered the murder of children. Therefore, compelling and evidentially-backed arguments for shared space are an absolute must before more widespread consideration of the concept can be pushed forward.
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Re: A523 Poynton - New "shared space" junction

Post by tggzzz »

Snipped quotation:
boing_uk wrote:The problem I have, professionally, is proving that {shared space} works. The difficulty is convincing the higher-ups, the councillors and the safety professionals that it is a suitable application. It would help a great deal if such schemes were publicised in promotional roadshows, or with some review by one of the Institutions that doesn't come across as a sales-pitch for BHB or Martin Cassini. As an engineer, I DESPERATELY need evidence to make a concerted and peer-reviewed argument for the installation of shared space in order to win over the traditionalists.
A responsible engineer will always examine claims carefully, and not believe them too credulously.

I agree with your assessment that too many presentations come across as sales pitches for Hamiltion-Baillie or Cassini. They seem to have a very zealous purist attitude that shared spaces are the answer to all problems! And that shared spaces don't have any disadvantages whatsoever. That's simply not credible.

All ideas, schemes, products etc have advantages and disadvantages, circumstances in which they are and aren't applicable, and only very rarely is there a single viable solution to a problem. In most situations there are multiple valid ways to skin the cat.

When assessing someone's proposals I look for statements of alternative solutions and each of their advantages and disadvantages. I then ask questions to see the limits of their proposals. If I hear "no, it isn't good for that" then I'm much more likely to believe them when they say "yes, it can do that". A poor salesman will
  • waffle without answering the question posed
  • attempt to befuddle me into thinking there's only one option
  • claim that option is applicable in all circumstances
Such salesman have little credibility. When I have avoided such traps and where politics/religion weren't a major factor, my proposals have been accepted.
boing_uk wrote: Therefore, compelling and evidentially-backed arguments for shared space are an absolute must before more widespread consideration of the concept can be pushed forward.
I agree.

You may be interested in a formal academic peer-reviewed study in which they videoed and interviewed pedestrians using a shared space scheme several years after it had been introduced. In addition they noted that the claims made for shared spaces could not be supported by the evidence provided by shared space advocates. The report is at http://eprints.uwe.ac.uk/16039/ and it is worth reading in its entirety to get the overall scope and context, and as a brief overview of the available literature and results.
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