Peter Gordon, Robert Cervero, and I discuss the cost-benefit analysis of Los Angeles rail investment in this issue of Public Works Management and Policy.
Here are the citations

Peter Gordon and Paige Elise Kolesar. A Note on Rail Transit Cost-Benefit Analysis: Do Nonuser Benefits Make a Difference?
Public Works Management & Policy April 2011 16: 100-110, first published on March 24, 2011 doi:10.1177/1087724X10397380

Robert Cervero and Erick Guerra
To T or Not to T: A Ballpark Assessment of the Costs and Benefits of Urban Rail Transportation
Public Works Management & Policy April 2011 16: 111-128, first published on March 24, 2011 doi:10.1177/1087724X10397379

and

Lisa Schweitzer
Benefit-Cost Analysis of Rail Projects: A Commentary Public Works Management & Policy April 2011 16: 129-131, doi:10.1177/1087724X11401035

Here are first few paragraphs of my commentary.

The debate in this issue of PWMP reflects a hardy perennial in the transportation community. With some consistency, rail transit fails to meet benefit–cost criteria or ridership forecasts. Planners and transit advocates—often these are the same—respond that benefit-cost analysis is only a partial measure of a project’s worthiness. How, they ask, do you monetize the benefits of something like a trolley that reinvigorates a slumping downtown? Some of the things we could never imagine living without—like the Brooklyn Bridge—would probably have failed a benefit–cost test back in 1866
when the New York legislature authorized it. And now the bridge is an architectural icon in a region whose economic health has come to rely at least in part on the aesthetics of investments made more than a century ago.

As vocal as transit advocates have become in dismissing those who question rail investment based on benefit–cost evaluations, rail advocates have more than earned the suspicion that surrounds them. Promise after promise accompanies the push to get federal dollars for local rail transit projects: for example, transit cleans up the air (not so much); it clears up congestion (not even close); it makes us thin (even though study after study demonstrates transit’s minuscule effects on obesity). Whenever anyone points out that projects have not delivered on their promises, then comes the next flood of promises: Jobs, jobs, jobs! Climate change! Building social capital! Economic development! Retail revitalization! At some point, investments have to be accountable for the promises made on their behalf. Cervero and Guerra contend that the mobility benefits accrue to future generations—future riders. If so, that is an empirical claim we can and should test. Some systems over time will jump over the bar their advocates set for them while others are unlikely to do so.