How Do Changes in Efficiency Affect Road Transportation Carbon Emissions? Efficiency-Biased Production-Theoretical Decomposition Analysis

Amid global climate mitigation efforts, China’s road transportation sector faces escalating tensions between persistent transportation scale growth and stringent decarbonization commitments. Existing studies have shown that efficiency improvement—defined as the ability to maximize transport output while minimizing resource inputs and reducing undesirable outputs—is one of the important means to achieve carbon emission reduction. However, the quantitative contributions of efficiency improvement in the change of road transport carbon emissions (RTC) still lack a systematic evaluation. This study pioneers an efficiency-biased production-theoretical decomposition analysis framework to investigate the role of efficiency in RTC changes across 30 Chinese provinces during 2010–2020. Key empirical findings include: (1) total factor production efficiency (TFPE) in road transportation increased from 2010 to 2018 but receded amid the pandemic, exhibiting regional disparities—the eastern region registered the lowest TFPE (e.g., Beijing and Shanghai < 0.6), whereas the central region (e.g., Hebei = 1) achieved optimal performance; (2) the expansion of the transportation scale constituted the principal impetus for RTC escalation, while potential energy intensity and TFPE emerged as key mitigating forces—among factor-specific efficiency effects, except for transport output biased efficiency effect, other factor-biased efficiency effects all contributed to reducing RTC; and (3) the potential for efficiency-driven emission reduction varied by region—capital-biased efficiency predominated in the west (32.9% annual average), labor-biased efficiency in the east (33.4%), while energy and carbon-biased efficiencies exhibited limited potential because of technological entrenchment. These results emphasize the need for region-specific policies: western China should prioritize green infrastructure upgrades, while eastern regions should leverage intelligent transport systems and labor training. The findings provide empirical support for optimizing emission control frameworks and inform strategies to harness efficiency potential for achieving China’s dual carbon goals.