The Environmental Supermodel

TMAA Detours

P.64, Edition 34, June 2021

Reducing transport-related pollution is a job for everyone in the industry, and as Paul Hutton in the UK writes, a solution being perfected in the English city of Oxford could help us here in Australia.


According to the European Environment Agency, transport is responsible for nearly 30 per cent of all the CO2 emissions in Europe. Of this, almost three-quarters – 72 per cent – comes from road transport. While this is a significant contributor to overall pollution levels, it is made worse because road vehicle pollution, including CO2 and other pollutants such as Nitrous Oxide and Sulphur Dioxide, is emitted inside our cities.


Other significant pollution sources, such as coal-fired power stations, are generally in isolated locations and not so impactful to city communities. While public opinion sways away from fossil-fuel energy generation, there does not seem to be the same emotive reaction to the impacts of road vehicle pollution on the climate, health and city liveability. Undoubtedly, the uptake of electric vehicles will be a significant driver in reducing localised road vehicle pollution, however I understand this is slower in the southern hemisphere mainly because of government incentives, charging infrastructure requirements, and the distances of inter-urban trips. Add to this the lack of domestic production and the lengthy supply chains, which contributes to the uncompetitive cost of electric vehicles.


One of the problems with improving air quality is that it is so weather-dependent. What happens to traffic fumes from the same stretch of road is different on different days. On hot, still days, it can linger over homes and offices, while on windy days, it gets blown out to sea, and the air we breathe is clear. A gentle breeze in one direction can lead to dangerously poor air quality in a school playground; another day, it could be outside a hospital.


Suppose cities are to increase their liveability, achieve emission and pollution goals while still enabling people and goods to move. In that case, a critical component is to adapt transport management systems to respond to these challenges. There are examples of Intelligent Transport Systems solutions from Europe used to manage traffic to prevent air quality from exceeding legal limits. In addition, many European cities have clean air and low emission zones to maximise the community environment and liveability. But while this has a significant effect on improving communities, the impact on productivity has to be considered and accommodated in either the transport management system or planning, as transport restrictions and costs reduce the efficiency of the network. Alternative solutions, therefore, need to be found if possible.


The Network Emissions and Vehicle Flow Management Adjustment (NEVFMA) project for Highways England centres on the A34 Botley Interchange to the west of Oxford City Centre (around 100km west of London) and addresses these challenges. The NEVFMA management system utilises advanced data analytics, AI and a behavioural-simulation modelling framework at a mesoscopic level to predict the speed and volumes of vehicular traffic in the city. By supplementing this framework with real-time traffic data and air quality monitoring, short term predictions of vehicle emissions and, subsequently, NO2 dispersal, are generated. With this sophisticated and predictive solution, traffic managers have the clarity and capability to make informed decisions on managing the network based on multiple priorities.

The solution is initially built in the Aimsun Next traffic simulation platform and the MappAir environmental mapping platform to create a static digital twin of the network. By adding real-time traffic information, accurate short-term predictions of the traffic network are generated using the Aimsun Live real-time platform. From this, emission levels can be predicted and interfaced with EarthSense’s pollution dispersion model to calculate the pollutant levels across the city in the immediate future, returning critical KPI data in around 10 minutes.


Predicting the traffic and environmental conditions in the city is an exciting opportunity; however, to be an effective end-to-end solution, transport network managers also need the system to be capable of decision support to proactively manage the transport network and the environment.

Should the system predict congestion or poor air quality, the managers can select a range of traffic management responses, which are then modelled to predict the outcome and provide metrics. The solution’s dashboard supports the manager by identifying the best operations plan, effectively managing the traffic build-up, and the reduce emissions before they have happened. The NEVFMA project provides the right strategy at the right time, reacting in real-time to changes in both traffic and weather to maintain the balance of the environment and city mobility.


One example of its effectiveness was when a lorry collided with the median barrier, separating the two carriageways of nearby the M40 motorway, causing its closure. The NEVFMA solution predicted the short-term knock-on effect on roads, including significant congestion on the alternative arterial A34. The system then identified the most efficient traffic management options, one of which was to divert northbound and southbound traffic onto alternative routes; splitting the traffic flows reduces idle time and keeps traffic flowing, reducing and dispersing the emissions. This kept air quality within legal limits, under the 40 μg/m  NO₂ threshold. Had the default traffic management solution been used, that limit would have been breached.


“This is a great example of where short-term modelling using real-time data can have a significant and measurable effect,” explained Aimsun’s UK Managing Director Gav Jackman. “Our solution doesn’t just wait for the traffic management solution to deal with the congestion that has built up, it predicts it before it has happened and can therefore minimise it. Because we took air quality into account in our modelling, the most environmentally friendly solutions are identified. Of course, if the weather is different, we might find another traffic management solutions that would have been better. The technology is vital in helping the traffic managers make the best decision.”


EarthSense managing director, Tom Hall has explained, “Working to investigate how traffic management and control systems can be used to reduce emissions in the Oxford area enables us to trial both the air quality predictions from MappAir and the Aimsun model. We hope that this will enable Oxfordshire County Council’s ambition to have the world’s first zero-emission zone to be realised. It should also prove the scalability of this project’s approach.”


Every time I have visited Australia, I have been struck by how your officials, and those from New Zealand, pride themselves on their cities’ ‘liveability’ – a subjective metric that reflects how desirable a city is to work, live and enjoy. However, I am also told how there are many examples of cities where air pollution significantly impacts the liveability and poses a genuine health risk, particularly affecting community health and recreation activities.


“This is an innovative use of a modelling solution, which could have a significant and speedy effect on air quality in cities across Australia,” added Aimsun’s Australian MD Scott Aitken. “In most places, we already have the modelling capability, the real-time traffic information and weather data, so using the technique developed in the UK is just a case of fusing it all. What’s so great about this solution is that we’ll be cleaning up the air by reducing traffic-related emissions in the places that matter, and, unlike so many other solutions, drivers won’t be inconvenienced, charged, fined or otherwise have reasons to complain.”


This NEVFMA innovation in the UK was developed for Highways England by Aimsun, EarthSense, Siemens and Oxfordshire County Council.


Paul Hutton is a writer and commentator on intelligent transport systems and communications professional


Paul Hutton

Aimsun Ltd.

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