Research on high-speed rail network optimization based on comprehensive efficiency, equity and environmental issues

High-speed rail (HSR) networks worldwide expanded in the recent decades, and especially China showed significant progress in implementing HSR within relatively short period of time. Economic efficiency was the primary motivation for the HSR 4X4 corridor expansion in the early phase while equity and environmental considerations are gradually taking the dominant position when extending the network to 8X8 corridors. The expansion of HSR into less developed regions and the associated debt accumulation problems raise the question what the limits are to HSR growth. Extended integrated as-sessment methods can be applied to support the decision making on the optimal network design under consideration of economic, environmental and social equity goals. The problems arising in China share similarities with other countries that are developing HSR networks, in particular in the European Union. Mirroring the Chinese way with international experience, a solution approach for optimal HSR network design is sketched out.