DataHub v1 is the original DataHub catalog of 11,000+ open datasets, now migrated to PortalJS Arc.
Dataset

High-speed-rail-by-country

Summary of the amount of operational, planned and under construction high speed rail lines in different countries around the world.

Download & API
High speed rail lines by countrygdocs/spreadsheet
Google doc showing KM of operational, planned and under construction high speed line in each country
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Sources & license