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release 98a--The Good news----and the bad news



The good news is that Edinburgh Council are now releasing the data but ---- the bad news is they’re still not calculating it correctly.




This picture shows the plain truth of the way traffic drives down Great Stuart Street --- anyone who knows the street, or takes the time to go there and watch the traffic for 5 minutes will see this is the fact.


The picture shows in the close up circle a Passive Diffusion Tube measuring pollution, attached to the street sign pole shown by the small arrow.


It shows a line of vehicles moving down the centre of the carriageway—the traffic flow is always at the centre of the carriageway.


In 2010 the council were ‘correcting’ traffic pollution measurements using the application of a mathematical ‘correction factor’ in which the distance from the measuring device, the Passive Diffusion Tube, to the ‘traffic flow’ is a vital element.


This distance matters because it changes the result, the shorter it is the lower the ‘corrected’ final published record of pollutants.


The higher this figures the higher the level of pollution.


Below shows the various possibilities on this street.





The Council were using the (i) 37 centimetre distance to calculate the pollution in 2010 when they were releasing the figures to justify statements that pollution was very low.


The residents pointed out that no traffic ever went down the kerbside because of the on street parking.


Parked cars come and go of course and sometimes bays can be empty, but the traffic never swerves in and out of empty bays ever, and it always hangs right in order to take the corner right, round a small painted mini roundabout, at the bottom of the street in the easiest way.


 After a long fight during which the council resisted for months they were forced to change from using distance (i) after the UK Government department responsible for Air Quality standards (DEFRA) issued newadvice to recognise the obvious, commonsense situation, that where parked cars occupy on-street spaces, then the carriageway should be assumed to run from the outside edge of the parked car – and not the kerb, distance (ii) above, 2.06 metres.


Although Edinburgh Council have now changed the way they apply correction factors to pollution readings, not just in Great Stuart Street but in a number of other streets across the city because of this. But they have never acknowledged publically that:


A) That they were not using the edge of parked car distance in 2010.




B) That the DEFRA advice change came after the residents group had contacted the UK government department with this photograph and this photograph helped prompt the change issued to all UK councils to remember to account for parked cars where these form a ‘virtual kerbside’.


They are now adding the 2.06 metres to the former calculation equation.


However as can be seen clearly above, the plain fact is that the traffic flow is in reality actually a further 1.8 metres (or so) distant from the Passive Diffusion tube—Distance (iii).


The council are not including this distance into their calculations. 


It may well be happening  because the person looking at a map and doing the calculation whether in the sub-contracted laboratory or the Council department, simply doesn’t know the facts of the traffic on the ground; they are pressing buttons on their calculator in a room, miles away.


That is excusable, but what is more difficult to excuse, is continuing to repeat the error.



This group make no secret of the fact that we believe more and more traffic is being displaced into residential streets and this is raising pollution levels inexorably towards, if not already beyond the EU statutory limits.


This is our agenda, it isn’t hidden in any way and it isn’t about minor issues of no importance.


The fact is these are questions with complicated aspects, but if the Council  cannot accept they are making a mistake in such a clear and straightforward thing as this distance calculation, what hope can we have they are getting the other things right?


Or is it that an apparently stupid position being adopted because the alternative is worse?