Industry Voices: Balancing Urban Congestion and Transport Emissions

Opinion piece by Andy Marchant, Traffic Expert at TomTom

You read it in the newspaper almost every week: traffic congestion is returning to pre-COVID levels – despite UK gasoline prices remaining at an all-time high.

While we have all experienced the positive effects of a world with less traffic over the course of the pandemic, traffic levels are increasing again as British citizens slowly but surely return to the office as part of their new working patterns. Local governments and city planners are therefore doing everything they can to reduce transport-related pollutants that are dangerous for the environment and human health. To improve overall air quality, many have introducing low emission zones that are designed to keep carbon-intensive vehicles out of city centers. For example, the Mayor of London recently proposed plans for the expansion of London’s Ultra Low Emission Zone (ULEZ), which would see the catchment area reach the Kent border. Meanwhile, Aberdeen, Dundee, Edinburgh and Glasgow introduced their own Low Emission Zones earlier this month.

These are positive developments when you consider the environmental cost of UK traffic congestion, which remains worryingly high. In London alone, 14.8 megatonnes (Mt) of CO2 was emitted in 2021 due to the capital’s road traffic, of which 15% (2.2Mt) was a direct result of congestion. To put this into perspective, the UK would need to grow a forest almost the size of Northern Ireland in one year, to capture London’s 2021 traffic-related emissions from the atmosphere.

Calling the future of low emission zones into question

With the UK government aiming to cease the sale of gasoline and diesel cars by 2030, low emission zones would ultimately become redundant in a few decades, with UK citizens and businesses required to switch to more sustainable vehicles.

Taking London as an example, we estimate that increasing the EV ratio by just 1% within the capital’s traffic mix would write off 155,000t of CO2 emissions – equivalent to a forest the size of Manchester (125km) to remove this amount of CO2 from the atmosphere. Based on this, it is clear that accelerating the switch to EV mobility will be essential for the UK to achieve its goal of net zero emissions by 2050.

Increased demand for charging stations must also be met. In the long-term, gas stations should be replaced with charging stations, where vehicles can take turns to charge before resuming their journeys. By then, technologies will likely be advanced enough that it takes less time to charge vehicles, taking minutes instead of hours.

Yet, this will result in more vehicles being welcomed back into city centres. While they would be free from harmful emissions, we cannot ignore that traffic congestion would increase enormously. Where certain vehicles previously had to bypass the city, they would once again be allowed to pass through it with ease.

Planning ahead for a more sustainable, less congested future

Fortunately, there are several solutions to combat both urban traffic emissions and congestion at the same time. For public authorities and city planners in particular, knowing how to influence traffic in order to ensure viable traffic flows and the efficient use of the infrastructure is critical. Traffic is connected to transport, commerce and a healthy economy, and using location technology will continue to be a game-changer for managing how people move around their cities.


However, better traffic management can only improve traffic flow by up to 10%. Therefore, to effectively tackle congestion and permanently put an end to the traditional rush hour peaks in cities, the modal split must be changed. Cycling, public transport and other modes of transport must take a larger share in transportation. These are simple solutions that we currently make too little use of.

Cities may also choose to implement congestion charges or zones where only a limited number of cars are allowed to drive during peak hours. Such a redirection requires greater collaboration between UK city planners, policy makers, employers, and drivers – and it will take time. However, this change is vital to truly minimise transport-related emissions, but still ensure that we tackle urban traffic congestion in a future where low emission zones become redundant.

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