From efficiency to equity: Changing patterns of China's regional transportation systems from an in-use steel stocks perspective

Transportation serves as a bridge for social production, distribution, exchange, and consumption and, thus, plays an important role in boosting the economy. In recent years, the rapid development of China's transportation system has driven a continuous accumulation of steel. In this study, we estimated the in-use steel stocks of 32 types of infrastructure and vehicles in three subsystems (railway, road, and subway) in 31 provinces of China from 1990 to 2019 based on a bottom-up approach. The results show that China's in-use steel stock in the transportation system has increased to 575 Mt in 2019 (34.4% for infrastructure, 65.6% for vehicle). Spatially, this increasing trend shows six diversified patterns among 31 provinces; steel stocks tend to decrease from the east to central and western inland areas. The Gini coefficient curve of the provinces' stocks shows an inverted "U" shape over time, indicating a shrinking regional gap in recent years; this reflects a transition from efficiency to equity. We also measured the steel stock productivity (GDP per stock) in different regions and observed its diverse evolution types. The stock productivities in all regions climbed up initially, but have dropped in recent years, and the most obvious decrease is observed in western China. For eastern regions, vehicles have been the main growth point in recent years, while western regions are vigorously developing infrastructure. Our results help to illustrate the development status and spatial distribution of China's transportation system and could facilitate improved efficiency and the management of future challenges in China's transformation and development.