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 amount of traffic per [[type]] and the distance from the source of emission. It also takes into account [[Building|object]]s and [[Elevation model|terrain features]] which would hinder 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>
===Traffic NO2 air polution overlay colors===
[[File:Traffic_NO2-Overlay_Legend.jpg|thumb|500px|right|Traffic NO2 overlay colors]]


==Calculations==
The Overlay implements SRM1{{ref|srm1}}, which is only applicable for urban environments.
The calculations follow the standard rekenmethode 1 (SRM 1), as described on [http://wetten.overheid.nl/BWBR0022817/2013-03-22]:
[[File:Traffic_NO2-Overlay-model.png|thumb|left|Traffic NO2 Model]]
{{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:
* 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


'''Cb,jm[NO2]= fNO2 * Cb,jm[NOx] + (B*Ca,jm[O3]*Cb,jm[NOx]*(1-fNO2))/(Cb,jm[NOx]*(1-Fno2)+K)'''
===Traffic===
Traffic intensities for each type of traffic can be based on one of the following:
* The [[Building attributes (Traffic NO2 Overlay)|Attributes of roads]] present in the [[project]].
* [[Prequels (Traffic NO2 Overlay)|Prequel Overlay]]s which define respective traffic intensities on a grid.


where:
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 NO2 Overlay)|HOURS model Attribute]].
* 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:
==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}}.


'''Cb,jm[NOx] = Fk * ENOx * θ * Fb * Fmeteo'''
==Results==
The following result types are available as output from the traffic NO2 calculations:


where:
{{result types|suppresscategory=true|allowselflinks=true|
* Fk = calibration factor [-] (default = 0.62]
{{:Concentration            result type (Traffic NO2 Overlay)}}
* ENOx = emission number NOx [μg/m/s]
{{:Emission no2            result type (Traffic NO2 Overlay)}}
* θ = delution factor [-]
{{:Emission nox            result type (Traffic NO2 Overlay)}}
* Fb = tree factor (default = XX)
{{:Treefactor              result type (Traffic NO2 Overlay)}}
* Fmeteo = 5/windspeed. Default value for windspeed is 5 m/s
{{:Trees                    result type (Traffic NO2 Overlay)}}
}}


The delution factor, θ, is computed till a distance of 30m with:
{{article end
 
|notes=
'''θ = a * S^2 + b * S + c'''
* The Overlay calculations are based on Standard Calculation Method 1 (SRM1) as defined by the dutch government.{{ref|srm1}}.
 
|howtos=
And from 30-60m (for road-type 1 and 4 only):
* [[How to add and remove an Overlay]]
 
* [[How to edit an overlay legend]]
'''θ = alpha * S^-0.747'''
* [[How to add a static traffic model]]
 
* [[How to add a static grid-based traffic model]]
where:
* [[How to add traffic data unaligned with roads]]
* S is the calculation distance
* [[How to add a dynamic traffic model]]
* a, b, c and alpha are parameters depending on road-type.
|references=
 
  <references>
[File:NO2 overlay 02.PNG]
    {{ref|srm1
 
      |name=SRM1
The weighted fraction direct emitted NO2 [-] is computed as:
      |author=
 
      |page=
'''fNO2 = ENO2/ENOx'''
      |source=Regeling beoordeling luchtkwaliteit 2007, Bijlage I
 
      |link=http://wetten.overheid.nl/BWBR0022817/2013-01-01#Bijlage1
where:
      |lastvisit=16-02-2022
* ENO2 = emission number NOs [μg/m/s]
    }}
 
  </references>
The emission numbers (E) for both NOx and NO2 are computed as:
}}
 
{{TrafficNO2Overlay nav}}
'''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)'''
{{Overlay nav}}
 
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
 
==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]

Latest revision as of 08:27, 29 February 2024

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 amount of traffic per type and the distance from the source of emission. It also takes into account objects and terrain features which would hinder 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:

Icon Result type Unit Mode Description
CONCENTRATION μg/m3 The concentration of NO2-equivalent pollution as a result of traffic.
EMISSION_NO2 μg/m3 The calculated emissions of NO2 due to traffic.
EMISSION_NOX μg/m3 The calculated emissions of NOX due to traffic.
TREEFACTOR factor The presence of trees (within 30 meters) as a fraction and converted to a factor between 1 and 1.5.
TREES boolean The presence of trees in any given location specifically.

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)
Traffic NO2 Overlay
Model attributes
Base o3 • Base no2 • Hours • Emission no2 • Emission nox • Emission jam no2 • Emission jam nox • Min tree height m • Cars active • Vans active • Trucks active • Buses active • Road1 30m a • Road1 30m b • Road1 30m c • Road1 60m alpha • Road1 60m power
Traffic features
Num cars • Num vans • Num trucks • Num buses • Jam factor cars • Jam factor vans • Jam factor trucks • Jam factor buses
Prequels
Cars • Vans • Trucks • Buses
Result types
Concentration • Emission no2 • Emission nox • Treefactor • Trees


Overlays
Categorization
Grid • Parent • Result Child • Result Parent • Result type
Default
City
Administrative
Ownership • Ownership Grid • Zipcodes • Zoning • Neighborhoods • Municipalities • Vacancy
Environmental
Heat Stress • Traffic Density • Traffic Noise • Traffic NO2 • Livability • Aerius
Water
Rainfall • Flooding • Groundwater • Subsidence • Watershed • Waterwijzer
Raster Calculation
Average • Combo • Distance • Sight Distance • Travel Distance
Geo Data
Area • Attribute • GeoTIFF • WCS • WMS • Image
Topography
Digital Surface Model • Digital Terrain Model • Underground • Function • Source
Network
Network Distance • Network Overview • Network Ownership


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