Traffic NO2 Overlay: Difference between revisions

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{{learned|what the Traffic NO2 overlay is|which information is displayed on the Traffic NO2 overlay|which additional information is displayed in the hover panel|how to add or remove the Traffic NO2 overlay|}}
The Traffic NO2 Overlay is an [[Grid overlay|overlay]] which displays the impact of traffic air polution (in &mu;g/m&sup3; NO2) in different colors for the project area. These colors indicate traffic air polution of a location based on [[Traffic Flow (Overlay)|traffic flow]] and distance.<br>
==What is the Traffic NO2 overlay?==
It becomes available for all stakeholders when added to a project.
[[File:Traffic_NO2-Overlay.jpg|thumb|left|Optional Traffic NO2 (Air polution effect) overlay]]
<br clear=all>
 
==Calculations==
The calculations follow the standard rekenmethode 1 (SRM 1), as described on [http://wetten.overheid.nl/BWBR0022817/2013-03-22]:
 
'''Cjm[NO2] = Ca,jm[NO2] + Cb,jm[NO2]'''
 
where:
* Cjm[NO2] = annual average concentration [μg/m3]
* Ca,jm[NO2] = annual average background-concentration (default = 0 [μg/m3], can be adjusted via the overlay attributes)
* Cb,jm[NO2] = annual average traffic contribution to NO2 concentration [μg/m3]
 
To compute the annual average traffic contribution to NO2, Cb,jm[NO2] [μg/m3], the following formula from SRM1 is applied:
 
'''Cb,jm[NO2]= fNO2 * Cb,jm[NOx] + (B*Ca,jm[O3]*Cb,jm[NOx]*(1-fNO2))/(Cb,jm[NOx]*(1-Fno2)+K)'''
 
where:
* Cb,jm[NOX] = annual average traffic contribution to NOx concentration [μg/m3]
* Cb,jm[O3] = annual average concentration ozon [μg/m3] (default = 42)
* fNO2 = weighted fraction direct emitted NO2 [-]
* B = parameter (default 0.6)
* K = parameter for conversion NO to NO2 (default = 100 μg/m3)
 
To compute the annual average traffic contribution to NOX, Cb,jm[NOX] [μg/m3], the following formula from SRM1 is applied:
 
'''Cb,jm[NOx] = Fk * ENOx * θ * Fb * Fmeteo'''
 
where:
* Fk = calibration factor [-] (default = 0.62]
* ENOx = emission number NOx [μg/m/s]
* θ = delution factor [-]
* Fb = tree factor (default = XX)
* Fmeteo = 5/windspeed. Default value for windspeed is 5 m/s


[[File:Traffic_NO2-Overlay.jpg|thumb|420px|left|Active Traffic NO2 air polution overlay]]
The delution factor, θ, is computed till a distance of 30m with:
The Traffic NO2 overlay is an [[Overlay]] which displays the impact of traffic air polution (in &mu;g/m&sup3; nitrogen dioxide) in different colors for the project area. These colors indicate traffic air polution of a location based on [[Traffic Flow (Overlay)|traffic flow]] and distance.
 
<br clear=all>
'''θ = a * S^2 + b * S + c'''
===Traffic NO2 air polution overlay colors===
 
[[File:Traffic_NO2-Overlay_Legend.jpg|thumb|500px|right|Traffic NO2 overlay colors]]
And from 30-60m (for road-type 1 and 4 only):
Traffic NO2 air polution is indicated in red (= bad) and green (= good)
 
<br clear=all>
'''θ = alpha * S^-0.747'''


==Additional information displayed in hover panel==
where:
[[File:Traffic_NO2-Hover.jpg|thumb|250px|left|Hover panel displays additional information]]
* S is the calculation distance
The hover panel gives the actual air polution value (in &mu;g/m&sup3; nitrogen dioxide) for the selected location when the overlay is active.
* a, b, c and alpha are parameters depend on road-type:
<br clear=all>


==Adding and removing==
[[File:NO2_overlay_02.PNG]]


{{Editor ribbon|header=Geo Data|bar=Overlays}}
The weighted fraction direct emitted NO2 [-] is computed as:


Adding and removing overlays is a generic process, however, certain overlays are dependent on other assets being present too, such as indicators, terrains, vacancy, images, etc. For more information please refer to the respective main articles for the specific overlays.
'''fNO2 = ENO2/ENOx'''


{{Editor steps|title=add the Traffic NO2 overlay|Select in the editor 'Geo Data' from the ribbon|Select 'Overlays' > 'Edit overlays' from the ribbon bar|Select the Traffic NO2 overlay from the drop down menu on the bottom of the left panel|Select 'Add' from the bottom of the left panel|The overlay icon will now appear under the mini map}}
where:
* ENO2 = emission number NOs [μg/m/s]


<gallery>
The emission numbers (E) for both NOx and NO2 are computed as:
File:Select3DWorld.jpg|1. Select Geo Data
File:SelectEditOverlay.jpg|2. Select Overlays > Edit overlays
File:SelectDropDown.jpg|3. Select desired overlay from drop down menu on the bottom of the left panel
File:SelectAddOverlay.jpg|4. Select 'Add' from the bottom of the left panel
File:OverlayIconPresent.jpg|5. The overlay icon will  now appear under the mini map
</gallery>


{{Editor steps|title=remove an overlay|Select in the editor 'Geo Data' from the ribbon|Select 'Overlays' > 'Edit overlays' from the ribbon bar|Select the desired overlay from the list of active overlays on the left panel|Select 'remove' from the bottom of the left panel|Confirm the removal in the pop up confirmation message}}
'''E = N * [(1-FS)*((1-(fm+fz+fb))*El + fm * Em + fz * Ez + fb * Eb) + FS * ((1-(fm + fz + fb)) * El,d + Fm * Em,d + fz * Ez,d+fb*Eb,d)]*1000/(24*3600)'''


<gallery>
where:
File:Select3DWorld.jpg|1. Select Geo Data
* N = traffic intencity [units per day]
File:SelectEditOverlay.jpg|2. Select Overlays > Edit overlays
* fm = fraction vans [-]
File:SelectOverlay.jpg|3. Select desired overlay from the list of active overlays on the left panel
* fz = fraction trucks [-]
File:SelectRemoveOverlay.jpg|4. Select 'Remove' from the bottom of the left panel
* fb = fraction busses [-]
File:ConfirmRemovalOverlay.jpg|5. Confirm the removal in the pop up confirmation message
* El = emission value cars [g/km]
</gallery>
* Em = emission value vans [g/km]
* Ez = emission value trucks [g/km]
* Eb = emission value busses [g/km]
* FS = fraction congested traffic [-]
* E*,d = emission factor per class (cars, vans, trucks or busses) if congested


''Sometimes it can be convenient to duplicate an already existing overlay. To do so, follow the steps for removal, but select 'Duplicate' in stead of 'Remove'.''
[[File:NO2_overlay_01.PNG]]


==References==
==References==
The overlay calculations are based on Standard Calculation Method 1 (SRM1) as defined by the dutch government: [http://wetten.overheid.nl/BWBR0022817/2013-01-01#Bijlage1 wetten.overheid.nl]
The overlay calculations are based on Standard Calculation Method 1 (SRM1) as defined by the dutch government: [http://wetten.overheid.nl/BWBR0022817/2013-01-01#Bijlage1 wetten.overheid.nl]
==How-to's==
* [[How-to add and remove an overlay|Add and remove an overlay]]
* [[How-to edit an overlay legend|Edit an overlay legend]]
{{Template:Overlay nav}}

Revision as of 15:05, 1 July 2019

The Traffic NO2 Overlay is an overlay which displays the impact of traffic air polution (in μg/m³ NO2) in different colors for the project area. These colors indicate traffic air polution of a location based on traffic flow and distance.
It becomes available for all stakeholders when added to a project.

Optional Traffic NO2 (Air polution effect) overlay


Calculations

The calculations follow the standard rekenmethode 1 (SRM 1), as described on [1]:

Cjm[NO2] = Ca,jm[NO2] + Cb,jm[NO2]

where:

  • Cjm[NO2] = annual average concentration [μg/m3]
  • Ca,jm[NO2] = annual average background-concentration (default = 0 [μg/m3], can be adjusted via the overlay attributes)
  • Cb,jm[NO2] = annual average traffic contribution to NO2 concentration [μg/m3]

To compute the annual average traffic contribution to NO2, Cb,jm[NO2] [μg/m3], the following formula from SRM1 is applied:

Cb,jm[NO2]= fNO2 * Cb,jm[NOx] + (B*Ca,jm[O3]*Cb,jm[NOx]*(1-fNO2))/(Cb,jm[NOx]*(1-Fno2)+K)

where:

  • Cb,jm[NOX] = annual average traffic contribution to NOx concentration [μg/m3]
  • Cb,jm[O3] = annual average concentration ozon [μg/m3] (default = 42)
  • fNO2 = weighted fraction direct emitted NO2 [-]
  • B = parameter (default 0.6)
  • K = parameter for conversion NO to NO2 (default = 100 μg/m3)

To compute the annual average traffic contribution to NOX, Cb,jm[NOX] [μg/m3], the following formula from SRM1 is applied:

Cb,jm[NOx] = Fk * ENOx * θ * Fb * Fmeteo

where:

  • Fk = calibration factor [-] (default = 0.62]
  • ENOx = emission number NOx [μg/m/s]
  • θ = delution factor [-]
  • Fb = tree factor (default = XX)
  • Fmeteo = 5/windspeed. Default value for windspeed is 5 m/s

The delution factor, θ, is computed till a distance of 30m with:

θ = a * S^2 + b * S + c

And from 30-60m (for road-type 1 and 4 only):

θ = alpha * S^-0.747

where:

  • S is the calculation distance
  • a, b, c and alpha are parameters depend on road-type:

NO2 overlay 02.PNG

The weighted fraction direct emitted NO2 [-] is computed as:

fNO2 = ENO2/ENOx

where:

  • ENO2 = emission number NOs [μg/m/s]

The emission numbers (E) for both NOx and NO2 are computed as:

E = N * [(1-FS)*((1-(fm+fz+fb))*El + fm * Em + fz * Ez + fb * Eb) + FS * ((1-(fm + fz + fb)) * El,d + Fm * Em,d + fz * Ez,d+fb*Eb,d)]*1000/(24*3600)

where:

  • N = traffic intencity [units per day]
  • fm = fraction vans [-]
  • fz = fraction trucks [-]
  • fb = fraction busses [-]
  • El = emission value cars [g/km]
  • Em = emission value vans [g/km]
  • Ez = emission value trucks [g/km]
  • Eb = emission value busses [g/km]
  • FS = fraction congested traffic [-]
  • E*,d = emission factor per class (cars, vans, trucks or busses) if congested

NO2 overlay 01.PNG

References

The overlay calculations are based on Standard Calculation Method 1 (SRM1) as defined by the dutch government: wetten.overheid.nl

How-to's