Emissions monitoring ‘fundamental’ at Highways England

Road congestion and real world emissions were among topics at the annual Dispersion Modellers User Group (DMUG) event

Road congestion and real-world emissions were among issues put under the spotlight by air quality experts at the annual Dispersion Modellers User Group (DMUG) conference in London yesterday (April 19).

The M1 motorway, which connects London to Leeds (photo: Peteri/

The M1 motorway, which connects London to Leeds (photo: Peteri/

Speakers at the event, organised by the Institute of Air Quality Management (IAQM), included Nigel Bellamy, air quality advisor at government agency Highways England and Dr Ben Marner, technical director at Air Quality Consultants Ltd.

Focusing on the newly developed DMRB GIS Toolkit (Design Manual for Roads and Bridges, Geographical Information System) Mr Bellamy said that monitoring emissions is “fundamental” for Highways England and “underpins everything they do”.

He noted that congestion is an important aspect in air quality monitoring, despite some of the featured models — notably the Streamlined-PCM (pollution climate mapping) — not featuring traffic congestion as a standard option.

The latest version of DMRB has been used at some of Highways England’s 1,500 monitoring sites across the country, Mr Bellamy said.

As part of the presentation — Mr Bellamy demonstrated emissions testing using DMRB over four periods throughout the day including peak times. It was found that in the afternoon, the flow of traffic goes up but importantly the emissions go down — attributed to the decreased use of Heavy Duty Vehicles (HDVs) at peak times.

“There is a strong emphasis on collaborative work between the road traffic team and air quality team” – Nigel Bellamy, Highways England

Highways England frequently monitor key locations with air quality risks, he added: “There is a strong emphasis on collaborative work between the road traffic team and air quality team.”

Real world emissions

Later, Dr Ben Marner turned the focus to real-world emissions, stating that Euro 4 and 5 diesel cars have “performed no-where near as good as in testing” but that “this is to become increasingly irrelevant over the next few years”.

He explained: “It is the performance of the vehicles that are coming onto the roads in the next few years that are going to hold the key to the future, rather than anything that has happened in the past.”

Discussing the new traffic emissions calculator, he said that in relation to Euro 5 vehicles, the COPERT (Calculation of Pollutant Emissions from Road Transport) 4 model, used in Defra’s Emissions Factors Toolkit (EFT) is “under-predicting emissions from heavy vehicles”.

Streamlined PCM

Also speaking at the event was Michel Verdenne, senior consultant at Ricardo Energy & Environment, who discussed the Streamlined-PCM tool and the impact of changing the measures applied as part of the tool on nitrogen oxides (NOx) and nitrogen dioxide (NO2) emissions at road receptors in the UK.

Mr Verdenne provided an overview of the tool’s use as a model of emission concentrations in Norwich, but explained that while the tool is currently used by Defra as part of its EU air quality directive, it is not currently available for widespread use.


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