Reducing Traffic Emissions Requires Parallel Solutions

Including Smarter Management of the Existing Vehicle Fleet

Traffic has rapidly become the largest source of emissions in Finnish cities. According to Helsinki’s Environmental Report (2025), traffic is expected to become the city’s biggest emission source in 2025. Helsinki has made significant progress in reducing emissions from heating and electricity by transitioning from coal to renewable energy (Helsingin kaupunki, 2024).

In Lahti, traffic accounts for approximately 32% of emissions, with over half coming from private cars (Moksu, 2025). According to YLE journalist Mika Moksu, Lahti – considered one of Finland’s most environmentally friendly cities – has not been able to implement politicians’ proposed projects beyond paper (2025).

The share of traffic in total emissions has become a critical bottleneck in achieving climate targets.

Behavioral Change Is Important – But Slow

Ville Lehmuskoski, Director of the Urban Environment Division in Helsinki, stated at ITS Finland’s network day on August 14, 2025, that although 80% of trips in Helsinki are made by walking, cycling, or public transport, and the share of electric vehicles is increasing, this is not enough to meet the city’s ambitious emission targets on schedule. If the targets are missed, the city will have to financially compensate for the consequences.

Sustainable mobility programs in cities have focused on promoting public transport, cycling, and walking. These are essential, as changes in travel behavior can influence traffic structure and emissions in the long term. However, changing behavior is slow and faces many challenges, especially when private cars remain the only realistic option for many people.

Many sustainable mobility projects are large infrastructure investments that require significant funding. In the current economic climate, cities may not be able to finance and implement them as planned, and assessing their impact is difficult.

Efforts to accelerate the adoption of electric vehicles include increasing the number of charging stations. However, the share of EVs in the vehicle fleet remains small, and the renewal of the current fleet is too slow.

Therefore, solutions that immediately affect emissions from the existing vehicle fleet are also needed.

Modern Vehicle Detection Enhances Intersection Traffic Flow

New detection technologies such as cameras, radars, and LiDARs are now affordable and easily replaceable. They enable more versatile and accurate vehicle identification and counting, improving traffic control. Adaptive software solutions utilize rich data more effectively – with AI and analytics, traffic light intersections can be better understood and incoming traffic flows predicted.

Currently, vehicle detection at traffic lights relies almost exclusively on induction loops, which detect vehicles as they pass over them. Induction loops cannot accurately differentiate vehicles or predict traffic, and they are prone to damage, especially in winter when studded tires wear down the asphalt. Repairs require excavation, causing both costs and long traffic disruptions. New detection technologies offer a more flexible and cost-effective solution.

Adaptive Solutions Deliver Immediate Results for Today’s Traffic Challenges

The core of traffic optimization is reducing unnecessary stops and starts. Each extra stop and acceleration increase fuel consumption and emissions. Adaptive solutions that respond in real time to traffic conditions improve flow and reduce emissions immediately after implementation.

If a camera or radar breaks, it can be replaced within hours, minimizing traffic disruption. In Denmark, SWARCO’s adaptive traffic management system demonstrated clear benefits: in a two-week comparison, stops decreased by 20% and starts by 11.5% thanks to the adaptive solution.

Potential to Reduce Emissions at Intersections

Ahn et al. (2002) showed that variations in vehicle speed and acceleration significantly affect fuel consumption and emissions. Based on these findings, starts may account for 50–60% of total emissions at intersections, while idling may contribute around 20–30%.

AI-based calculations suggest that adaptive traffic light control can reduce unnecessary stops and accelerations, lowering emissions at a single intersection by an average of 11%. The savings potential depends on traffic volumes, structural complexity, and vehicle mix. Heavier vehicles produce more emissions, and large, complex intersections are more emission-intensive than smaller ones.

Estimates suggest that one signal-controlled intersection produces about 100–700 tons of CO₂ emissions annually. If adaptive technology were widely implemented across the network, the total impact could reach tens of thousands of tons per year. This estimate does not include additional benefits from reduced traffic disruptions.

Although adaptive solutions alone cannot achieve cities’ ambitious emission reduction goals, they offer a measurable and concrete part of the overall solution alongside vehicle electrification and the promotion of sustainable travel modes.

Conclusion

Reducing traffic emissions requires a combination of parallel solutions. Sustainable mobility and the rise of electric vehicles are vital long-term strategies, but they must be complemented by technologies that deliver immediate impact and do not rely on changing human behavior.

Smart traffic control systems and adaptive solutions offer a cost-effective and quickly deployable tool – a way to support cities’ carbon neutrality goals starting today.

References

Ahn, K., Rakha, H., Trani, A., & Van Aerde, M. 2002. Estimating vehicle fuel consumption and emissions based on instantaneous speed and acceleration levels. Journal of Transportation Engineering, 128(2), 182–190. https://doi.org/10.1061/(ASCE)0733-947X(2002)128:2(182). Also available at: https://www.researchgate.net/publication/252692078_Estimating_Vehicle_Fuel_Consumption_and_Emissions_Based_on_Instantaneous_Speed_and_Acceleration_Levels [Accessed 26 August 2025].

Helsingin kaupunki. 2024. Helsingin CO₂-päästöt vähenivät – liikenteen päästöjen osuus kasvussa. Published June 13, 2024. Available at: https://www.hel.fi/fi/uutiset/helsingin-co2-paastot-vahenivat-liikenteen-paastojen-osuus-kasvussa [Accessed August 26, 2025].

Helsingin kaupunki. 2025. Helsingin kaupungin ympäristöraportti 2024. [PDF document]. Available at: https://www.hel.fi/static/julkaisut/talous-strategia-hallinto/ymparistoraportti-2024.pdf [Accessed August 26, 2025].

Lehmuskoski, V. 2025. ITS Finland verkostopäivä – Digitalisaatio liikenteen päästönieluna. YouTube. [Live recording]. Published August 14, 2025. Available at: https://www.youtube.com/watch?v=A1IpVOg9Igs [Accessed August 26, 2025]. Lehmuskoski’s speech begins at 00:39:10.

Moksu, M. 2025. Virallisesti vihreä Lahti ei pääse eroon autojen päästöistä. Yle. Published March 31, 2025. Available at: https://yle.fi/a/74-20150490 [Accessed August 26, 2025].