The RapidEMS module enables the rapid calculation of emissions rates for a range of key pollutants – including oxides of nitrogen (NOx), particulate matter with a diameter of less than 10 microns or 2.5 microns (PM10 and PM2.5 respectively) and carbon dioxide (CO2) – for specific years, road types (e.g motorways, urban), vehicle speeds and fleet composition. The default version of RapidEMS uses COPERT 5.3 coefficients. In the UK, RapidEMS is designed to align with the latest version of the Department for Environment, Food and Rural Affairs’ (Defra) Emissions Factors Toolkit 10.1 (EFT, 2020). However, variations of RapidEMS is available to support research Internationally. Emissions are calculated for every vehicle category including cars, motorcycles and light goods vehicles (LGVs), heavy goods vehicles (HGVs) and buses. The module considers fleet renewal and partitions composition by European emission standards inclusive of Euro 6/VI, weight class and fuel type. Scaling factors are then applied to enable changes due to fuel improvements and retrofitting to be considered.
Optional feature:
Bespoke emissions factors
In addition to the default version of RapidEMS, RapidAir subscribers are able to add bespoke emission factors for specific geographical locations. This includes the potential to include real world emissions factors from Ricardo’s vehicle emissions remote sensing database, under a bespoke agreement.
Ricardo’s real-world emissions factors developed from remote sensing measurements taken at numerous locations across the UK from over 500,000 vehicles.
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RapidAir
Roads dispersion module
RapidAir is based on AERMOD, the USEPA’s recommended dispersion model for traffic emission sources. It is a steady-state dispersion model, in which pollutants are assumed to disperse away from their source in a plume with a Gaussian concentration profile in both directions perpendicular to the plume centreline.
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Met
Metrological module
Providing high-quality meteorological data is a key requirement for undertaking robust and defensible air quality modelling. RapidAir has been designed to enable users to quickly process and undertake quality assurance (gap filling using the United States Environmental Protection Agency (USEPA) methodology) of the met data driving their simulations.
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Canyons
Street canyon model and allocator
In built-up urban areas, air pollution can become trapped in street canyons – streets surrounded by tall buildings. As such, the impacts of canyons are important elements of any robust air quality modelling system. Street canyon models range from complex computational fluid dynamic (CFD) models to simpler empirical (such as the USEPA STREET box-model and semi-empirical models (such as the Danish Operational Street Pollution Model (OSPM)). RapidAir includes a canyon module based on the AEOLIUS system developed by the UK Met Office.
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