Tyler Cowen from the blog Marginal Revolution discusses A cost-benefit analysis of high-speed rail, following up on the critique of Glaeser by Avent and Freemark and others.
... "I'm not sure what discount rates he is using but even if we put that problem aside this screams out: don't do it. Given irreversible investment, lock-in effects, and required hurdle rates of return, this still falls into the "no" category. And that's an estimate from an advocate writing a polemic on behalf of the idea. I'm not even considering the likelihood of inflation on the cost side or the public choice problems with getting a good rather than a bad version of the project. How well has the Northeast corridor been run? "