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|}}
[[File:Traffic_NO2-Overlay.jpg|thumb|right|Traffic NO2 Overlay]]
==What is the Traffic NO2 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 [[project]]. The calculation takes into account the amounts- and types of traffic, and the distance from the source of emission. It also takes into account [[Building|object]]s and [[Elevation model|terrain features]] which would block the travel of particles.


[[File:Traffic_NO2-Overlay.jpg|thumb|420px|left|Active Traffic NO2 air polution overlay]]
The Overlay only takes into account NO2 emissions from traffic. Other sources of emissions (such as air traffic of factories) are explicitly excluded.
The Traffic NO2 overlay is an [[Overlay]] which displays the impact of traffic air polution (in μg/m³ 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>


==Adding and removing==
The Overlay implements SRM1{{ref|srm1}}, which is only applicable for urban environments.
To add a traffic NO2 overlay go to the Overlays menu in the GEO DATA ribbon and select Add Traffic NO2. To remove the overlay, press Remove below the overlays list.
[[File:Traffic_NO2-Overlay-model.png|thumb|left|Traffic NO2 Model]]
{{clear}}


[[File:NO2_overlay_03.PNG|700px]] [[File:NO2_overlay_04.PNG|700px]]
==Configuration==
{{main|Model attributes (Traffic NO2 Overlay)}}


==Calculations==
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.
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]'''
The following aspects can be configured:
* Base concentrations of NO2 and NOx
* Emissions per vehicle type both in motion and in traffic jam
* Constants for road-based dilution factors
* The hour(s) of the day to perform the calculation for


where:
===Traffic===
* Cjm[NO2] = annual average concentration [μg/m3]
Traffic intensities for each type of traffic can be based on one of the following:
* Ca,jm[NO2] = annual average background-concentration (default = 0 [μg/m3], can be adjusted via the overlay attributes)
* The [[Building attributes (Traffic NO2 Overlay)|Attributes of roads]] present in the [[project]].
* Cb,jm[NO2] = annual average traffic contribution to NO2 concentration [μg/m3]
* [[Prequels (Traffic NO2 Overlay)|Prequel Overlay]]s which define respective traffic intensities on a grid.


To compute the annual average traffic contribution to NO2, Cb,jm[NO2] [μg/m3], the following formula from SRM1 is applied:
The traffic intensities can be defined as either a single value or as 24 hours, with each value corresponding to each hour of the day. The intensity used for the calculation is then defined by the [[Hours (Traffic Noise Overlay)|HOURS model Attribute]].


'''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]], the presence of [[Building|trees]], and the [[Building attributes (Traffic NO2 Overlay)|Attributes of roads]] present in the [[project]]. The calculations follow the standard rekenmethode 1 (SRM 1){{ref|srm1}}.


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:
{{result types|suppresscategory=true|allowselflinks=true|
{{:Concentration            result type (Traffic NO2 Overlay)}}
{{:Emission no2            result type (Traffic NO2 Overlay)}}
{{:Emission nox            result type (Traffic NO2 Overlay)}}
{{:Treefactor              result type (Traffic NO2 Overlay)}}
{{:Trees                    result type (Traffic NO2 Overlay)}}
}}


'''Cb,jm[NOx] = Fk * ENOx * θ * Fb * Fmeteo'''
{{article end
 
|notes=
where:
* The Overlay calculations are based on Standard Calculation Method 1 (SRM1) as defined by the dutch government.{{ref|srm1}}.
* Fk = calibration factor [-] (default = 0.62]
|howtos=
* ENOx = emission number NOx [μg/m/s]
* [[How to add and remove an Overlay]]
* θ = delution factor [-]
* [[How to edit an overlay legend]]
* Fb = tree factor (default = XX)
* [[How to add a static traffic model]]
* Fmeteo = 5/windspeed. Default value for windspeed is 5 m/s
* [[How to add a static grid-based traffic model]]
 
* [[How to add traffic data unaligned with roads]]
The delution factor, θ, is computed till a distance of 30m with:
* [[How to add a dynamic traffic model]]
 
|references=
'''θ = a * S^2 + b * S + c'''
  <references>
 
    {{ref|srm1
And from 30-60m (for road-type 1 and 4 only):
      |name=SRM1
 
      |author=
'''θ = alpha * S^-0.747'''
      |page=
 
      |source=Regeling beoordeling luchtkwaliteit 2007, Bijlage I
where:
      |link=http://wetten.overheid.nl/BWBR0022817/2013-01-01#Bijlage1
* S is the calculation distance
      |lastvisit=16-02-2022
* a, b, c and alpha are parameters depend on road-type:
    }}
 
  </references>
[[File:NO2_overlay_02.PNG]]
}}
 
{{TrafficNO2Overlay nav}}
The weighted fraction direct emitted NO2 [-] is computed as:
{{Overlay nav}}
 
'''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]

Revision as of 09:30, 2 March 2023

Traffic NO2 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 project. The calculation takes into account the amounts- and types of traffic, and the distance from the source of emission. It also takes into account objects and terrain features which would block the travel of particles.

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

The Overlay implements SRM1[1], which is only applicable for urban environments.

Traffic NO2 Model

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:

  • Base concentrations of NO2 and NOx
  • Emissions per vehicle type both in motion and in traffic jam
  • Constants for road-based dilution factors
  • The hour(s) of the day to perform the calculation for

Traffic

Traffic intensities for each type of traffic can be based on one of the following:

The traffic intensities can be defined as either a single value or as 24 hours, with each value corresponding to each hour of the day. The intensity used for the calculation is then defined by the HOURS model Attribute.

Calculation

Main article: Traffic NO2 formula (Traffic NO2 Overlay)

The Traffic NO2 Overlay performs its calculations based on the Overlay's Attributes, the presence of trees, and the Attributes of roads present in the project. The calculations follow the standard rekenmethode 1 (SRM 1)[1].

Results

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

Notes

  • The Overlay calculations are based on Standard Calculation Method 1 (SRM1) as defined by the dutch government.[1].

How-to's

References

  1. 1.0 1.1 1.2 SRM1 ∙ Regeling beoordeling luchtkwaliteit 2007, Bijlage I ∙ Found at: http://wetten.overheid.nl/BWBR0022817/2013-01-01#Bijlage1 ∙ (last visited: 16-02-2022)