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Science
16 March 2025

Integrated Strategies Cut Port City Freight Emissions

Combining fleet electrification with road improvements offers significant emission reductions for Shenzhen.

An Integrated Approach Combines Fleet Electrification and Road Network Development to Cut Emissions

Port cities, recognized as pivotal hubs within global supply chains, are grappling with the dual challenges of rising traffic emissions and increased vulnerability to climate-related impacts. A new study focusing on Shenzhen, one of the world's busiest port cities, reveals significant opportunities for emission reductions through integrated strategies combining fleet electrification and improvements to road networks. The research highlights the necessity of tackling emissions from the road freight sector, especially as China moves toward its ambitious carbon goals.

The study analyzes more than 1.2 billion GPS signals from heavy-duty trucks (HDTs) operating within Shenzhen, providing high-resolution data to project emissions from 2016 to 2035. The results indicate potential emissions cuts of up to 34% for carbon dioxide (CO2) and 43% for nitrogen oxides (NOx) when combining the electrification of heavy-duty fleets with enhancements to road connectivity, surpassing the benefits of electrification alone.

“An integrated strategy decreases road freight emissions, cutting peak carbon dioxide and nitrogen oxide emissions by 34% and 43%, respectively, compared to electrification-only scenarios,” wrote the authors of the article.

Road freight continues to be a significant contributor to emissions in China’s transport sector. Despite efforts to encourage modal shifts and reduce reliance on trucks, the fleet has increased by 92% over the past decade due to rising trade demands. Heavy-duty trucks are responsible for more than three-quarters of emissions from the road transport sector, worsening public health risks associated with air pollution.

The study emphasizes the urgency for port cities to implement effective emission reduction measures, particularly because they are home to heavily populated urban zones. Shenzhen alone is responsible for 80% of China’s containerized cargo handling and suffers from concentrated HDT activities leading to high emission levels near residential areas, thereby heightening health risks for its citizens. The study found significant correlations between population density and the emissions produced by HDTs, underscoring the disproportionate impacts of truck emissions on densely populated regions.

Utilizing high-resolution emissions inventory models, the research incorporates traffic flow simulations to evaluate how improved road networks influence emissions. “While fleet electrification supported by net-zero emission grids is necessary, it is insufficient without addressing congestion and enhancing connectivity through expanded road networks,” wrote the authors of the article.

The findings have broader implications for urban planning, proposing strategies to improve freight transport infrastructures. Enhanced connectivity could lead to more direct routes and less congestion, resulting in reduced travel times and emissions. The expected adoption of electric trucks and advanced infrastructure shows promise for reducing long-term emissions, especially when paired with renewable energy grids.

Projections indicate continued growth of the heavy-duty truck fleet within Shenzhen, forecasted to expand to 66,000 units by 2035. With increasing freight demand, the study warns of anticipated increases in emissions without strategic infrastructure improvements combined with fleet electrification.

The research supports policymakers by offering actionable insights based on observed real-world data. Through spatially explicit emission inventories, city planners can develop targeted strategies for varying urban contexts globally. Port cities can adapt this study's framework, facilitating emission reductions where most needed—particularly within high-traffic zones and areas with elevated public health risks.

“This comprehensive approach guarantees immediate and long-term sustainability in port cities,” the study concludes, stressing the importance of integrating fleet electrification with road network enhancements to meet carbon neutrality goals.

Encouragingly, the tools developed may serve as templates for other cities seeking to reduce emissions effectively. By emphasizing the dual strategies of electrification and infrastructural development, urban areas can confront their significant transportation emissions and work toward healthier environments for residents.

Overall, this research highlights the urgent need for port cities like Shenzhen to take integrated action. Policymakers and urban planners have the opportunity to achieve meaningful reductions in emissions, fighting against the backdrop of growing urban freight demands influenced by global supply chains.