LTN: Our Healthy Streets - Dulwich: Phase 3

[goldilocks]

Just in case anyone is reading this at face value - this is an incorrect summary . It is nothing to do with adjusted monitoring data.

Rockets Wrote:

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> And for all the people in the room the claimed

> reduction in that section is only because the

> council "adjusted" their Jan 19 monitoring data to

> create a number for Sept 19 - they magically

> increased the number of car journeys from 12,408

> in Jan 19 to 15,316 on Sep 19. Without that magic

> formula applied that section still shows an

> increase comparing actual data (albeit from Jan

> instead of September).

>

> Does anyone know what Cllr Rose's secret sauce is

> for the calculations?

>

> The fact the council claim a 28% increase on the

> EDG East section, a -17% decrease on the Central

> section and a 17% increase in the South section

> should be ringing alarm bells - those monitoring

> sites are within a few hundred yards of each other

> and the fact they "adjusted" the central one

> probably provides people with the answer they

> need.

>

> Unless, does someone have an explanation for the

> discrepancy rather than just doing the "well

> people of EDG Central section our 100 yard section

> of road was a success at least"!

[Dogkennelhillbilly]

Monkey Wrote:

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>

> Happy to leave my car behind but give me good

> local transport.

...and local transport can't improve until more private drivers leave their cars behind and get out of the way of buses.

[Rockets]

goldilocks Wrote:

-------------------------------------------------------

> Just in case anyone is reading this at face value

> - this is an incorrect summary . It is nothing to

> do with adjusted monitoring data.

>

> Rockets Wrote:

> --------------------------------------------------

> -----

> > And for all the people in the room the claimed

> > reduction in that section is only because the

> > council "adjusted" their Jan 19 monitoring data

> to

> > create a number for Sept 19 - they magically

> > increased the number of car journeys from

> 12,408

> > in Jan 19 to 15,316 on Sep 19. Without that

> magic

> > formula applied that section still shows an

> > increase comparing actual data (albeit from Jan

> > instead of September).

> >

> > Does anyone know what Cllr Rose's secret sauce

> is

> > for the calculations?

> >

> > The fact the council claim a 28% increase on

> the

> > EDG East section, a -17% decrease on the

> Central

> > section and a 17% increase in the South section

> > should be ringing alarm bells - those

> monitoring

> > sites are within a few hundred yards of each

> other

> > and the fact they "adjusted" the central one

> > probably provides people with the answer they

> > need.

> >

> > Unless, does someone have an explanation for

> the

> > discrepancy rather than just doing the "well

> > people of EDG Central section our 100 yard

> section

> > of road was a success at least"!

But why then is the East Dulwich Grove Central section the only to include both a Jan 19 and Sept 19 set of numbers?

And why then does it say: *Pre-implementation data for January 2019 has been adjusted to September 2019 levels to ensure comparability"

Whilst all of the other slides says: *Pre-implementation data has been adjusted to September 2019 levels to ensure comparability

[goldilocks]

This is exactly right and accounts for the majority of the change in the monitoring that was included in the June data.

In addition. In ONLY using the count nearest to Lordship Lane the pre figures were only collecting the numbers of vehicles coming from Lordship lane onto EDG, but not including any joining from Elsie, Derwent or Melbourne and turning right (or left from MGS) towards Townley. Therefore the 'pre' figure is understated for this central location.

By using actual counts that existed before the schemes were put in and comparing this to actual counts in the same place after, this is how it can be seen that traffic has fallen outside the Charter School / Hospital site.

Jenijenjen Wrote:

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> In very simple terms:

>

> Before LTNs

> 100 cars travel east from Townley Road

> 20 of these cars turn into Melbourne Grove

> 80 cars travel along eastern end EDG to LL

>

> After LTNs

> 100 cars travel east from Townley Road

> None of these cars can turn into Melbourne Grove

> so 100 cars travel on eastern section of EDG

>

> There has been no increase in number of cars

> Townley Road to Melbourne Grove

> But an increase of 20 cars I.e. 20% for the

> section of road from Melbourne to LL

>

> Which explains an increase in only one section of

> the road

[heartblock]

It hasn't fallen. Cars cannot disappear as they have nowhere to go. Sept 2021 report admits a rise in traffic on ED Grove - it's quite simple.

[Mrs D]

Thanks for that Jenijenjen (I forgot Townley!). But I presume if you turn left from Townley on to EDG - that traffic count has increased as Calton is closed?

[heartblock]

and where is the air quality data????

[exdulwicher]

And for all the people in the room the claimed reduction in that section is only because the council "adjusted" their Jan 19 monitoring data to create a number for Sept 19 - they magically increased the number of car journeys from 12,408 in Jan 19 to 15,316 on Sep 19. Without that magic formula applied that section still shows an increase comparing actual data (albeit from Jan instead of September).

Formulae get adjusted all the time to take into account differences in gathering the data, new modelling, timeframes and all sorts of other factors to allow accurate comparisons. A lot of statistical methodology involves some built-in adjustment for (eg) small datasets, very large datasets, non-normal distributions and so on.

You can also do large scale data transformations; so if one set of data follows a logarithmic curve but you want to use it alongside another set of linear data for example.

It's like saying that something cost ?1000 in 1970 and then adjusting to inflation to show that today's price would be nearly ?16,000 (yes, that is correct, I just ran it through a calculator). It allows an accurate comparison that the person in the street can get their head around. The figures haven't been manipulated, they've been explained more clearly.

[legalalien]

I am just going to repeat that I think everything would be much clearer and we (me) would get a much better view of what is going on if all the data was presented in numbers rather than percentages.

I have just emailed my Streetspace comments to the council, explaining that I understand that a consultation isn't a referendum, but that it has a point viz enabling officers to take advantage of the significant resource that is local knowledge, to supplement the desk-based studies being done at Tooley Street or some outsourced location elsewhere. I think it's the council that's mistakenly characterising it as a popularity poll, that they can then justify ignoring on the "not a referendum" basis. Of course they won't take any notice, but at least responding helps avert the "not so many objections, people must have come around to our view" narrative.

Saw a sign on a lamppost today suggesting that parking etc in Gilkes Place (between DV and the closure point) is being suspended to enable construction work on the Aquinna thing until (I think) October 2022. Will go and re-read it properly later.

[heartblock]

https://www.the-spokesmen.com/johnstewartltns/

[goldilocks]

I know its difficult when facts are presented that show that the theory you've been shouting about for a year is totally incorrect, and there's a cycle of grief that you have to go through, but at some point you have to stop claiming that your eyes are a better guide than a traffic monitor.

Probably worth adding here that the October figures for that section of East Dulwich Grove show that traffic fell even further.

heartblock Wrote:

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> It hasn't fallen. Cars cannot disappear as they

> have nowhere to go. Sept 2021 report admits a rise

> in traffic on ED Grove - it's quite simple.

[Rockets]

I am not sure it does as how do you then account for the 500 or so vehicles that are disappearing along the section from LL to the Central monitoring point every day - there is no longer anywhere for them to go so why are those numbers so different in the Sep 21 numbers?

Also it does state in the report that the EDG Central monitoring site was new for Sep 21 so how did they get the data from Jan 19 and Sep 19 to deliver the "reduction".

Also the below doesn't stack up because of the position of the Central monitoring point because the cars turning onto Melbourne Grove from EDG heading east would have already passed the threshold.

Before LTNs

> 100 cars travel east from Townley Road

> 20 of these cars turn into Melbourne Grove

> 80 cars travel along eastern end EDG to LL

>

> After LTNs

> 100 cars travel east from Townley Road

> None of these cars can turn into Melbourne Grove

> so 100 cars travel on eastern section of EDG

[heartblock]

'facts' ... the disappearing cars...and don't gaslight my eyes, ears and lungs please - yet again we are gaslighted for what we see, hear and breath.

[goldilocks]

Rockets - very few cars cutting down MG to go to eg Grove Vale would have historically gone on EDG at all.

The central section of EDG was understated by assuming that the count data from near to Lordship applied to the whole section. That counter would not include any cars driving south along the now filtered roads and turning right to go west on EDG.

The EDG monitoring site outside the health centre was a location that was monitored at various points pre the Dulwich "healthy streets" initiative. It has also been a location for DFT manual counts too so can corroborate the reasonableness of the data via that publicly available set.

[goldilocks]

You know that pointing out actual counts isn't gaslighting...

heartblock Wrote:

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> 'facts' ... the disappearing cars...and don't

> gaslight my eyes, ears and lungs please - yet

> again we are gaslighted for what we see, hear and

> breath.

[Jenijenjen]

Deleted as Goldilocks responded far more knowledgeably than me

[Rockets]

goldilocks Wrote:

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> Rockets - very few cars cutting down MG to go to

> eg Grove Vale would have historically gone on EDG

> at all.

>

> The central section of EDG was understated by

> assuming that the count data from near to Lordship

> applied to the whole section. That counter would

> not include any cars driving south along the now

> filtered roads and turning right to go west on

> EDG.

>

> The EDG monitoring site outside the health centre

> was a location that was monitored at various

> points pre the Dulwich "healthy streets"

> initiative. It has also been a location for DFT

> manual counts too so can corroborate the

> reasonableness of the data via that publicly

> available set.

So why then does it say that the EDG Central site is a new monitoring site for Sep 21 - your position is somewhat undermined by the council's own document....which says: This is a new site for data collection, having started in September 2021?

Also the point that Jenijenjen made is baseless as well because if there had been a monitoring point there those cars turning down Melbourne Grove from EDG would have been counted already before turning.

No matter where you suggest the traffic is coming from the "reduction" in the EDG Central section does not look at all accurate given the increase in the two sections of road book-ending it.

Or are you trying to claim over 3,000 cars a day were going down Melbourne Grove?

[goldilocks]

It is a new monitoring site for the LTN monitoring. This really isn't the conspiracy you're trying to make it Rockets. The council didn't include that site in the first two rounds of monitoring it did as part of the streetspace review. It has now been included. Hence it is 'new'.

Yes - it would have been better if it had been included from the outset - not least as it would have prevented people getting so entrenched with a view that they can't accept that data doesn't back it up.

There are historic counts at the same place that have been used for comparison.

[Rockets]

So what you, and the council are saying then, is that 3,000 cars a day were going down Melbourne Grove/Derwent and now aren't and that is why there is a "decrease" on EDG Central?

[andrewc]

How do people feel about the increase of 60% in bike use?

[goldilocks]

Its not 'decrease' - its an actual decrease.

I think from memory thre were around 3000 vehicles a day on MGN. Derwent and Elsie less than this but still quite a lot. Also need to consider MGS too.

Just in case you missed it above. The previous count point that was used for comparison was near to lordship lane so wasn't actually counting all the traffic that previously travelled along the middle section of ED Grove.

Thankfully there are traffic counts from pre the measures. Both council and DFT that show this to be true - eg the number of vehicles in the central section was greater than the bit by Lordship Lane.

The 'new' count done in September shows that traffic has fallen since the measures went in and has fallen further in October.

Rockets Wrote:

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> So what you, and the council are saying then, is

> that 3,000 cars a day were going down Melbourne

> Grove/Derwent and now aren't and that is why there

> is a "decrease" on EDG Central?

[heartblock]

How much clearer can you get than Southwark's own graph shown here?

[Otto2]

That's brilliant news - thanks for explaining!

[Rockets]

I am still not buying it I afraid - way too many holes in the council's data and way too many if, buts, maybes and asterisks on how they compared different data sets recorded on different dates in different years. Look at the Turney Road debacle or the detailed analysis of cycling figures put out by the council.

It remains a "decrease" for many of us until the council provides some clarity, some more details on methodology and timings of monitoring etc - which, of course, they have promised but failed to deliver. I presume they are briefing you, and the other residents on Melbourne Grove on this, seeing as you have something of the inside scoop ;-)!

The point remains - you are celebrating one section of one road that you happen to live on/near that has experienced a "decrease". Shame for those sections either side of yours hey....

[heartblock]

And....from Southwark again - a 28% rise in traffic..as I have said