Yet another entry about high-speed rail

The national bloggers continue to debate the feasibility of a high-speed rail link between Houston and Dallas.  Up to bat:  Megan McArdle.

I think reasonable people can disagree about the feasibility of HSR, especially since we’re just trading  back-of-the-envelope calculations of HSR’s costs and benefits.  Although I’ve argued HSR opponents underestimate the benefits to business-class passengers, in the interest of fair and balanced coverage, let me point to Richard Green’s discussion of a more rigorous effort to tote up the costs and benefits.  The authors of that particular study give HSR the thumbs down.

And while I’m in a contrary mood, let me suggest one other potential cost of a Houston-Dallas line.

Everyone agrees that in order for such a line to succeed, it must draw airline passengers to rail.  Lots and lots of airline passengers.  If the airlines lose, say, half of their Houston-to-Dallas traffic, they will have to cut the number of flights between Houston and Dallas.  Obviously.  Many consider that a feature, not a bug.

But what about the effect on other routes?  American is able to offer service from Dallas to virtually every American city because of the huge number of passengers flowing into DFW every day.  Cutting that inflow will reduce the economies of scale that support so many flights.  Ditto with Southwest out of Hobby.    Houston is a huge feeder for DFW, if the number of Bush-to-DFW flights is any indication.  Similarly, Love is a huge feeder for Hobby, judging by the 24+ daily flights.  Networks can be delicate things.  Shrinking one route could sicken other segments. 

HSR could very well make it easier to get from Houston to Dallas and vice versa.  But it could very well make it harder to get anywhere else.