Measuring the spatiotemporal variation and evolution of transport network of China's megaregions

Megaregion has become a prominent feature of modern China. Reflecting upon China's recent path of transport infrastructure construction, this research examines the spatiotemporal characteristics of transport network development and its accessibility impacts in China's ten megaregions from 1982 to 2010. Using historical transport network data and multiple national censuses (1982, 1990, 2000 and 2010), we computed two levels of indicators of megaregional transport network: megaregion level and county level, and analyzed the intra-megaregion and inter-megaregion disparities of transport network of the ten megaregions of China. Transport networks at the megaregion level are measured by three indicators: 1) transport network density; 2) infrastructure endowment per capita; and 3) size of transport network's standard ellipse. Two accessibility indicators for measuring transportation network at the county level are calculated: weighted average travel time and potential accessibility. The research results show the following: 1) Road and rail network densities witnessed the greatest growth during the 2000-2010 period, and growth was more significant for railway network. 2) By 2010, average road endowments per capita in inland megaregions became higher than in coastal megaregions, while average rail endowments per capita in coastal megaregions became higher than in inland megaregions. 3) The sizes and directions of the standard deviational ellipses of road and rail network changed continuously during the study period. However the changes of road network ellipses were relatively small, while the changes of railway network ellipses were more significant. 4) Megaregions have all benefited significantly from transportation infrastructure improvement in the past few decades in terms of WATT and potential accessibility, but the three giant megaregions benefited most.