A study by Alstom and consulting company Carbone 4 in France has revealed that tramways have a smaller CO2 footprint than bus rapid transit (BRT) systems. 

As part of the study, it was found that urban transport emissions worldwide are expected to double to nearly one billion tonnes of CO2 equivalent per annum by 2025.

Rail has been identified as a key contributor to cut greenhouse gases (GHGs) and is expected to reach the target set at Conference of Parties COP21 last year to keep temperature rises below 2°C.

Carbone 4 associate director Julien Blanc said: “Reducing greenhouse gas emissions from transportation is both a key issue and an exciting challenge.

“Tramways are of course part of the solution and these infrastructures will benefit from all the improvements in cleaning the electricity mix.”

The study involved comparison of the carbon footprint of  tramways and BRT systems. Results revealed that trams have a low environmental impact when in operation and is the greenest urban transport mode.

"Reducing greenhouse gas emissions from transportation is both a key issue and an exciting challenge."

The comparison gives a better understanding of the performance of both systems over the entire lifecycle, including their construction, operation and maintenance.

Alstom sustainable development director Cécile Texier added: “The survey conducted with Carbone 4 illustrates that rail systems have a lower carbon footprint that other motorised modes.

“It also shows that optimised system like Attractis, an innovative integrated tramway system that is simpler to operate and cost-effective, can significantly reduce CO2 emissions from the construction phase.”

After performing an analysis on a typical 10km line operated in Belgium, Alstom and Carbone 4 found that a tramway system generally emits around half the CO2 of a BRT system operated with diesel buses.


Image: The study involved comparison of the carbon footprint of tramways and BRT systems and found that the tram has a lower environmental impact. Photo: © Alstom.