Transport is one of the sectors in which Romania must reduce the pressure on the climate and on air quality. According to Romania’s Long-Term Strategy for reducing greenhouse gas emissions (GD 1215/2023), between 1990 and 2019 emissions from the transport sector rose by 41%, reaching 18,937 kt CO₂ equivalent in 2019, with road transport as the dominant source — around 96% of the sector total.
source: https://sgg.gov.ro/1/wp-content/uploads/2023/11/ANEXA-1-21.pdf
On the DN1 – Otopeni – Bucharest corridor, this reality is visible day after day: the link between the capital, the northern area and Henri Coandă International Airport depends largely on cars, taxis and other road vehicles. Metro Line 6 changes that calculation, offering a public transport alternative that is fast, predictable and with far lower operational emissions per passenger.
Car versus metro
Here is a comparison, taking as a reference the road distance of roughly 16–17 km between the Gara de Nord area and Henri Coandă International Airport / Otopeni. Our World in Data indicates, on the basis of UK government reporting factors, around 170 g CO₂e/km¹ for a petrol car and around 35 g CO₂e per passenger-km for national rail transport.
For urban electric systems of the light rail / metro type, the 2024 UK government methodology (DESNZ – GHG Conversion Factors) indicates an average of 26.16 g CO₂e per passenger-km, and for the Glasgow Underground a value of 34.70 g CO₂e per passenger-km. These values are international benchmarks for comparison, not official factors specific to Metro Line 6 or to Romania.
Applying these benchmarks to a distance of 16–17 km, a car journey with a single occupant generates approximately 2.7–2.9 kg CO₂e one way, or 5.4–5.8 kg CO₂e for a return trip. For urban electric transport (26–35 g CO₂e per passenger-km), the same journey would generate approximately 0.42–0.60 kg CO₂e one way, or 0.83–1.19 kg CO₂e return.
The difference is significant: for every passenger who chooses the metro instead of a private car, the estimated saving is around 2.1–2.5 kg CO₂e one way, or 4.2–5.0 kg CO₂e for a return journey. Assuming a car with a single occupant, the metro can have a carbon footprint some 5 to 6.5 times smaller per passenger-km, depending on the emission factor used and on how heavily the system is loaded.
The other emissions matter too
CO₂ is not the only relevant pollutant. Road traffic generates nitrogen oxides, carbon monoxide and particulate matter, PM10 and PM2.5. According to the European Environment Agency (EEA) – Emissions of air pollutants from transport, the pollutants emitted by transport contribute to the deterioration of air quality and put pressure on human health. Although exhaust emissions have fallen in recent decades, particles from the wear of brakes, tyres and road surfaces remain an important component of the pollution generated by road transport.
The electric metro produces no exhaust emissions along its route. Therefore, for journeys transferred from car or taxi to the metro, Metro Line 6 will help reduce local emissions in the areas it crosses and ease the pressure created by road traffic on the Otopeni – Bucharest corridor. The benefit is not only climatic but also urban: more public transport means more predictable mobility, a more efficient link with the airport and a real alternative for the residents, employees and visitors of the northern area of the capital.
Metro Line 6 is a public utility project of national interest, which provides the link between the metro network and Henri Coandă International Airport and contributes to the development of the trans-European transport network TEN-T. The project is not only an investment in infrastructure, but also an urban mobility measure with direct effects on emissions, air quality and connectivity between Bucharest and the airport.
¹CO₂e/km = carbon dioxide equivalent per kilometre. CO₂e (CO₂ equivalent) is a unit of measurement that includes not only carbon dioxide (CO₂) but also the other greenhouse gases, expressed as CO₂ equivalent. Cars also emit methane (CH₄) and nitrous oxide (N₂O), not just CO₂. CO₂e adds them all into a single figure, converting them according to their global warming potential. In practice, for a car the difference from pure CO₂ is small, so when the article says “170 g CO₂e/km”, it can be read as “roughly 170 g of greenhouse gases per km, expressed as CO₂”. Per km means per kilometre travelled, with a single passenger in the car (or per passenger-km for public transport, where the emissions are divided by the number of people in the vehicle).
Sources:
Romania’s Long-Term Strategy (GD 1215/2023) | Our World in Data – Travel Carbon Footprint | UK Gov GHG Conversion Factors 2024 | CNAB – Statistical data 2024 | EEA – GHG emissions from transport | EEA – Pollutants from transport
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