All big projects have studies that support the financials of the projects. The assumptions supporting China's cost benefit analysis look more realistic than the studies for California's high speed rail.
Here is the cost benefit analysis for California high speed rail.
There is an OECD study from 2009 of high speed rail which looks at the benefits for french high speed rail after the fact.
There is a lengthy study on the economic benefits of high speed rail for Europe
Here is a study of the co-benefits of high speed rail.
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