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Figure 3. PRISMA 2020 flow diagram.
Average speed emission models
Average speed emission models estimate total emissions based on the average speed of vehicles (spatial
average speed). These models are typically used to assess aggregate emissions and long-term trends at urban
or national scales. Representative examples include Computer Program to calculate Emissions from Road
Transportation (COPERT), Emission Factor (EMFAC), and Mobile Source Emissions Factor (MOBILE).
The COPERT model is the European Union (EU) standard vehicle emission calculator coordinated by the
European Environment Agency (EEA) . It calculates emissions and energy consumption for specific
[32]
countries or regions using input parameters such as vehicle fleet composition, mileage, average speed, and
ambient temperature. COPERT distinguishes among three main emission sources: hot engine operation,
cold starts, and fuel evaporation. The model estimates emission factors through speed-dependent regression
[33]
functions .
The EMFAC model, developed by the California Air Resources Board (CARB), is widely used to evaluate
emissions from on-road vehicles in California. It defines emission factors across speed bins (typically in
