Is there a breakdown of the estimated costs anywhere?

I see a lot of speculation over how "it's expensive because of X" (e.g., unions, land owners, regulations, etc.), but I don't think I've ever seen a detailed breakdown of the estimated costs which would support anyone's hypotheses as to why it's actually as expensive as it is.

For all I know, the high-speed rail project is going to cost $231B because it calls for using osmium rails in its tracks.