Sustainable Urban Transportation Approaches: Life-Cycle Assessment Perspective of Passenger Transport Modes in Qatar

Transportation is one of the most responsible sectors for human health impact and greenhouse gas emissions. The transportation mode in Qatar is primarily passenger car; consequently, the significant amount of environmental impact can result. Metro system has been introduced as a strategy to transition urban environments into low carbon by reducing emissions from passenger cars. This study compares the environmental impacts of the metro, passenger car, and bus transportation modes using a life-cycle assessment method from cradle to gate for the case of Qatar. GaBi 6.0 software was used to model and quantify the environmental impacts per functional unit of passenger-kilometer. Our analysis demonstrates that metro is more sustainable concerning all impact categories when compared to buses and cars. Most importantly, the metro transport is vital in addressing the critical environmental impacts in the transportation sector, namely global warming, human health particulate matter, and smog. A metro line can reduce approximately 12.3 Mton of CO2 emissions, 457.13 ton of human health particulate matter, and 0.061 Mton of smog air annually. Electricity is the prime contributor to the environmental impact of the metro system; therefore, its impact can be further improved by using a cleaner energy source from renewables.