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The Transport Agency has developed a vehicle emission mapping tool(external link) that automates calculation of both harmful air pollutants and greenhouse gas emissions. The tool can be applied to all public roads throughout New Zealand.

The tool is housed in a geographical information system (GIS) framework so that data can readily be presented as maps. The tool extracts data from the Transport Agency’s information technology systems, which builds a detailed data set of input variables for the emission calculations.

A matrix of vehicle emission factors, extracted from the New Zealand Vehicle Emission Prediction Model (VEPM 5.3), is used with the input variables to calculate the mass of pollutant per length of roadway.

Maps can be produced that allow users to explore how vehicle emissions vary at a range of spatial scales from national to local. The tool has flexibility to be used for analyses including:

  • Developing inventories of harmful air pollutant and greenhouse gas emissions
  • 'What if' emission scenario testing (eg changes in fleet and speed)
  • Assessing the impact of changing emission factors 
  • Reporting trends in emissions over time
  • Understanding the network impact of transport projects
  • Supporting investigations into the health effects of exposure to vehicle emissions

Validation of the tool has involved comparing output data with local authority air pollutant emissions inventories. The results demonstrate that the tool can be used as a reliable and consistent means of generating vehicle emission datasets at various geographical scales throughout New Zealand.

Documentation on the development of the vehicle emission mapping tool are referenced below.

For further information contact environment@nzta.govt.nz.

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