2023 mobility system stocks

Roads and rail-based mobility infrastructures are the basis for mobility services and underpin several Sustainable Development Goals, but also induce material use and greenhouse gas emissions. A recent study led by our CircEUlar member Dominik Wiedenhofer conducts a global assessment of material stocks in mobility infrastructure (roads and rail-based systems, including bridges and tunnels), their associated material flows, and embodied greenhouse gas (GHG) emissions for 2021.

It combines Open Street Maps data with archetypical designs to estimate material stocks for 180 countries, mapped at a 5 arcminutes resolution. The research reveals a global accumulation of 314 Gt of materials in mobility infrastructure, predominantly in roads, with significant disparities in distribution between countries and across different areas. The annual material flows for infrastructure expansion and maintenance are about 8 Gt/year, equating to around 6% of global resource extraction and leading to 0.36 Gt CO2eq/year, approximately 1% of global GHG emissions in 2021. A notable finding is that two-thirds of these flows are due to maintenance and replacement, indicating a significant resource use lock-in from existing infrastructures.

The results underscore the importance of strategic spatial planning and limitations on infrastructure expansion for sustainable resource use and climate change mitigation. This comprehensive analysis provides insights into the biophysical basis of global mobility services and stresses the environmental impact of infrastructure, highlighting the urgent need for a shift towards more sustainable and efficient mobility systems.