Abstract | Another way to look at vehicle emissions

The NZ Transport Agency has commissioned work to develop a tool that automates calculation of both harmful air pollutant and greenhouse gas emissions from motor vehicles. The tool has been applied across the state highway network and local authority roads throughout New Zealand.

A geographical information system (GIS) framework is used to house the tool so that it can readily present data as maps that are useful for engaging with both technical and non-technical audiences.

The vehicle emission mapping tool extracts data from the Transport Agency’s information technology systems, which is used to develop a detailed data set of input variables needed for the emission calculations.

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

The tool has so far been used to create a national vehicle emission dataset for 2016 but has been designed to allow future datasets to be calculated quickly and easily as new input data becomes available.

Maps can be produced that allow users to explore how vehicle emissions vary at a range of spatial scales from national to local. It also has the flexibility to be used for the following types of analyses:

• Developing inventories of harmful air pollutant and greenhouse gas emissions.
• What if emission scenario testing (e.g. 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.

Bio | Rob Hannaby MEIANZ CEnvP

Rob is the National Environment and Urban Design Manager at the New Zealand Transport Agency. He is a Certified Environmental Practitioner with over 25 years of experience working in the UK and NZ in the field of environmental management, in particular noise and air quality. Rob enjoys working collaboratively across the transport and environmental sectors to enable the delivery of public good outcomes.

He is the current secretary of the World Road Association (PIARC) environment committee and has managed the Transport Agency Environment and Urban Design team since 2013. The team includes a number of specialists covering a broad range of disciplines including; landscaping, cultural heritage, community and stakeholder engagement, resource efficiency, environmental management systems, urban design, ecology, storm water, noise and air quality.