China has proposed an ambitious high-speed rail (HSR) program by 2030 to connect all provincial capitals (excluding Lhasa) and large cities with more than half million people. Little attention has been paid to evaluate its potential impacts on ground transportation accessibility. To answer this question, we adopted a door-to-door approach to calculate two indicators: the weighted average travel time and daily accessibility. The results show that the HSR network follows the same spatial patterns of population size and regional development, thus preferentially serving eastern China. The two accessibility indicators suggest that the large-scale construction of HSR network by 2030 will substantially improve accessibility and alter the spatial disparities of accessibility. On average, accessibility of all cities will increase by 61.7%. Geographically, cities with higher accessibility are located in the quadrilateral area of ‘Wuhan-Zhengzhou-Jinan-Nanjing’ on the southeastern section of the ‘Hu Line.’ While the least accessible cities are distributed in peripheral areas. Although the HSR development can benefit accessibility throughout the country, the disparities of accessibility would widen slightly among regions, provinces and cities.

It is well known that the increasing development of transport infrastructure will result in temporal and spatial convergence. As an important component of China’s high-speed rail (HSR) network, an ambitious HSR building program in Jiangsu province will extend the network to cover all cities and 95% of counties by 2030. This study aims to present and analyze the impacts of the evolving HSR network in Jiangsu province over the period of 2010–2030 by developing multi-phased isochrone maps of Nanjing city (the provincial capital of Jiangsu province). During the process, layered cost distance, a new method based on a door-to-door approach in actual travel time calculations, is proposed in order to draw the maps at a more detailed geographical level. Our results are expected to facilitate proactive public policy decisions related to improving the transport network.