One of the problems with the American rail debate is you have people who like rail and people who like low taxes. The two don't overlap. Thus, the former sees any opportunity to lay rail as an opportunity to hose taxpayers.
"China’s high speed rail with a maximum speed of 350 km/h has a typical infrastructure unit cost of about $17-21m per km, with a high ratio of viaducts and tunnels, as compared with $ 25-39 [million U.S. dollars] per km in Europe and as high as $ 56 [million U.S. dollars] per km currently estimated in California" [1]. The Seattle/Washington per-mile costs above translate to $78 to $625 million dollars per kilometre.
[1] http://www.worldbank.org/en/news/press-release/2014/07/10/co... 2014