The transport sector produced 20% of direct CO2 emissions in 2014 (Worldbank). Almost all (95%) of the world's transportation energy comes from petroleum-based fuels, largely gasoline and diesel. urban transport accounting for about 40% of end-use energy consumption (IPCC, 2014). For example, in the EU, urban mobility accounts for 40 % of all CO2 emissions of road transport and up to 70 % of other pollutants from transport. Looking at public transport use, in 2015, 243 billion public transport journeys were made in 39 countries around the world. This figure represents an 18% increase compared to 2000 (UITP, 2017).

Cities themselves are usually in the best position to find the right responses to these challenges, taking their specific circumstances into account. A central approach is to leverage opportunities in public purchasing such as transport service contracts, infrastructure development or vehicle fleet innovation.

These opportunities offer entry-points to apply sustainable public procurement in support of a low emission transport sector. For instance, public authorities award contracts to service providers only if contributing to low carbon mobility. In addition to emission reduction, there are other benefits coming with a sustainable transport sector such as cleaner air, noise reduction, public safety and lower congestion levels.