Traffic NO2 Overlay: Difference between revisions

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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>
[[File:Traffic_NO2-Overlay.jpg|thumb|right|Optional Traffic NO2 (Air polution effect) overlay]]
It becomes available for all stakeholders when added to a project.
The Traffic NO2 Overlay is a [[Grid Overlay]] which computes the impact of traffic air pollution (in &mu;g/m&sup3; NO2) for any given location in the [[3D World]]. The calculation takes into account the amounts- and types of traffic, and the distance from the source of emission.
[[File:Traffic_NO2-Overlay.jpg|thumb|left|Optional Traffic NO2 (Air polution effect) overlay]]
<br clear=all>


==Calculations==
The Overlay only takes into account NO2 emissions from traffic. Other sources of emissions (such as air traffic of factories) are explicitly excluded.
The calculations follow the standard rekenmethode 1 (SRM 1), as described on [http://wetten.overheid.nl/BWBR0022817/2013-03-22]:
{{clear}}


'''Cjm[NO2] = Ca,jm[NO2] + Cb,jm[NO2]'''
==Configuration==
{{main|Model attributes (Traffic NO2 Overlay)}}


where:
The Traffic NO2 Overlay has a number of options which allow it to be configured as desired. A [[Traffic NO2 Overlay Wizard|configuration wizard]] is available.
* 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:
The following aspects can be configured:
* Emissions per vehicle type both in motion and in traffic jam
* Constants for road-based dilution factors


'''Cb,jm[NO2]= fNO2 * Cb,jm[NOx] + (B*Ca,jm[O3]*Cb,jm[NOx]*(1-fNO2))/(Cb,jm[NOx]*(1-Fno2)+K)'''
==Calculation==
{{main|Traffic NO2 formula (Traffic NO2 Overlay)}}
The Traffic NO2 Overlay performs its calculations based on the [[Model attributes (Traffic NO2 Overlay)|Overlay's Attributes]], and the [[Construction attributes (Traffic Overlay)|Attributes of roads]] present in the [[3D World]].


where:
==Results==
* Cb,jm[NOX] = annual average traffic contribution to NOx concentration [μg/m3]
The following result types are available as output from the traffic NO2 calculations:
* 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:
{{article end
 
|howtos=
'''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:
 
[[File: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
 
[[File:NO2_overlay_01.PNG]]
 
==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]
 
==How-to's==
* [[How to add and remove an Overlay]]
* [[How to add and remove an Overlay]]
* [[How to edit an overlay legend|Edit an overlay legend]]
* [[How to edit an overlay legend]]
 
|references=
{{Template:Overlay nav}}
* 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]
}}
{{Overlay nav}}

Revision as of 11:50, 11 February 2022

Optional Traffic NO2 (Air polution effect) overlay

The Traffic NO2 Overlay is a Grid Overlay which computes the impact of traffic air pollution (in μg/m³ NO2) for any given location in the 3D World. The calculation takes into account the amounts- and types of traffic, and the distance from the source of emission.

The Overlay only takes into account NO2 emissions from traffic. Other sources of emissions (such as air traffic of factories) are explicitly excluded.

Configuration

Main article: Model attributes (Traffic NO2 Overlay)

The Traffic NO2 Overlay has a number of options which allow it to be configured as desired. A configuration wizard is available.

The following aspects can be configured:

  • Emissions per vehicle type both in motion and in traffic jam
  • Constants for road-based dilution factors

Calculation

Main article: Traffic NO2 formula (Traffic NO2 Overlay)

The Traffic NO2 Overlay performs its calculations based on the Overlay's Attributes, and the Attributes of roads present in the 3D World.

Results

The following result types are available as output from the traffic NO2 calculations:

How-to's

References

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