Report highlights extent of road emissions in Hillingdon

But study finds that measures such as moving to different modes of transport would make a difference, writes Amy North

Road transport in the London borough of Hillingdon contributes to 95% of the total carbon dioxide emissions in the borough, in addition to 77% of nitrogen oxides and 69% of particulate matter, according to a new study.

But the report, which does not take into account emissions from Heathrow airport, found that the emissions could be reduced by measures such as the introduction of Crossrail in 2017, which is predicted to reduce borough-wide emissions by more than 2%, or a dedicated Uxbridge to Heathrow bus service — if it uses cleaner buses.

Road transport in Hillingdon is a major cause of emissions

The report was produced by consultancy the Transport Research Laboratory,  on behalf of Hillingdon council, which wants to reduce emissions through measures outlined in its Air Quality Action Plan and Transport Local Implementation Plan (LIP).

The findings in the report were generated using a tool produced by TRL known as the Transport Enhanced Emissions Model (TEEM). This tool can now be used by the council and allows officers to estimate the impact these measures could have on emissions in the borough.

Speaking to Kevin Turpin, one of the authors of the report, explained why the report was commissioned.

He said: “Our tool provides an alternative or new platform for Hillingdon to test or examine various measures that they may be thinking about implementing as part of their Transport Local Implementation Plan.

“It enabled them to test out various scenarios. It looks at the change in emissions and allows them to build a much more comprehensive scenario so we don’t have to look at only one measure, we can look at joint measures as long as we know what the inputs are likely to be.”

Mr Turpin explained that the council could input detail for up to five different types of vehicles on one road, their average speed and traffic flow over a 24 hour period to gain detailed analysis on the emissions.


Looking forward, Mr Turpin said that TRL was developing a web-based version of the tool, which it aims to launch in July. The web-based version would allow local authorities to more easily share information on emissions and analyse emissions on roads that cross council boundaries.

He also said that after the report was published in April 2012, the London borough of Hounslow had also implemented a similar tool and he expected more councils to take it up in the future.


Looking at other forms of transport, the report found that emissions from the diesel railway network contributed to 23% of overall NOx emissions, 31% of PM emissions and 5% of CO2 emissions.

Meanwhile it found that CO2 emissions from electric trains were approximately double that of diesel powered ones, however NOx emissions were approximately half while PM emissions were at a similar level.

In the report four measures from the LIP were assessed for their impact on emissions in the entire borough or given area. It found:

  • Achieving modal shift targets in the LIP were found to reduce emissions of NOx, PM and CO2.
  • Introducing a dedicated Uxbridge to Heathrow bus service may increase emissions in the short term (due to a large increase in the numbers of buses), but if cleaner buses were used, there would be longer-term emissions reductions.
  • On a per-passenger basis, emissions reductions were found due to improvements to a bus and train transport interchange at Uxbridge. For example, for all pollutants, emissions due to increased bus patronage buses were predicted to reduce more than 25% and by more than 60% for increased train use.
  • The introduction of Crossrail in 2017 was predicted to reduce borough-wide emissions by more than 2%.


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