How data can help with air quality management

Ian Larbey, Air Quality Lead at Bosch UK explains how data can help with air quality management.

Brixton, London is an easy place to imagine, it has a tube station, lots of buses, plenty of taxis and more delivery vans than ever before.  

Brixton also marks the end of the Victoria Line and so its tube station is the hub of the area. It’s outside of here, on Brixton Road, where pedestrian footfall is the highest.  

Where pedestrians and road traffic are present together the topic of localised air quality management becomes very important. 

While it sounds like a bleak picture, Brixton isn’t particularly better or worse than most London boroughs when it comes to air quality. 

We mention it here because Brixton is where Transport for London (TfL) has worked with Bosch to understand how air quality on Brixton high street changes minute by minute and day by day. 

‘We wanted to create a trial based on the hypothesis that localised air quality can be improved through advanced traffic management,’ explains Ian Larbey, Bosch UK Air Quality Lead. 

 ‘We worked with TfL over a 20-month period concluding at the beginning of this year and it enabled TfL to try new technologies and products. The project gave us valuable experience of working with city authorities and the local borough.’ 

Brixton was chosen as the location because it’s one of TfL’s air quality focus areas.  

‘We supplied 17 of our advanced air quality sensors,’ says Ian.  

‘But this project went much further than that. Data was key here and we really ramped up our ability to combine existing data and interpret it in a useful way.  

‘Our joint project teams analysed the local vehicle fleet which was key to understanding the traffic flow behaviour and resultant traffic emission contribution along the A23 and surrounding roads. We utilised our Air Quality Dispersion Model that considered the weather conditions, 3D building layout and topology to develop a simulated air quality map.’ 

Bosch was therefore able to help TfL measure the air quality in Brixton minute-by-minute and the causes of peaks and troughs could be tied accurately to traffic, vehicle and environment data. 

‘We used anonymised number plate recognition to define the emission class of the vehicles and powertrain mix of the overall fleet, whether it’s vehicles being powered by petrol, diesel, hybrid or fully electric,’ says Ian.  

‘This was complemented by other data available through TfL including loop counters that are already installed in the road. 

‘Data analysis allowed us to intelligently tune the traffic control within the area to enable improvement in traffic flow, which in turn reduced emissions and thus improved the local air quality.’ 

Understanding the influence of the wind was also an important aspect to the project. Windy conditions increase the speed and direction of dispersion. The Bosch air quality boxes measured the air for a range of pollutants including nitrogen dioxide (NO2), and ozone (O3), as well as particulate matter (PM2.5). 

As with many things in 2020, the first Covid-19 lockdown had an impact on the results.  

However, the lockdown period wasn’t included in the data analysis. After the first lockdown the local authorities changed a bus lane into a pedestrian lane so that there was a greater distance between people walking along the high street. This also had an impact on the project and increased NOx in the area. 

What’s clever about this project is that Bosch was able to explain to TfL how the data had been impacted by weather, the lane closure, different vehicles and how traffic lights and traffic flow impacted the air quality.  

This methodology equips partners with a tool that can be used for advanced network air quality simulation or within Intelligent Traffic Control Systems where changes in AQ may be susceptible to weather conditions, peak travel time or road closure associated with construction or events. 

Bosch’s advanced IT infrastructure and skills meant the sharing of these results was straightforward.  

The Brixton project was a success. Some of the data was startling in its clarity. A reduction of NOx on Brixton Road averaging 6% was recorded, but it was closer to 20% before the lane closure influenced the results. Traffic speed increased from 8.7mph to 10.6mph.  

‘Further projects can be done to enhance our understanding of how air quality changes depending on a variety of different factors,’ says Lionel Vancon, Bosch’s Air Quality Product Manager in Europe.  

‘Anything is possible with this technology such as analysing other emissions sources like trains, housing and other background factors. This trial in Brixton had a range of very positive outcomes. We conclusively reduced emissions. What’s really great is the traffic light signalling strategy will continue to be used in Brixton to improve traffic flows and air quality.  

‘The lessons that we’ve learnt will be used to inform TfL’s future traffic management plans. The project can be scaled up or down to provide similar analysis with a great level of reliability in any other location and we’re really excited to deploy this further within the UK and beyond.’ 

 This article first appeared in the November Air Quality News Magazine, click here to view.