If you haven't noticed, I mostly blog about urban economics and Austin development. I rarely blog about transportation issues, though, and when I do I mostly write about congestion pricing of roads.
So where are my posts on light rail? That ought to be within my bailiwick.
The short answer is "comparative advantage." There are lots of other people who know more about this stuff and who write about it regularly. MIEK and the Overhead Wire cover light rail all the time (the latter multiple times a day), and they both know far more than I about the technical details -- stuff like acceleration rates and track widths and catenaries. I could try to learn that stuff, but why?
Rail sparks ferocious arguments, and I don't particularly want these to hijack my blog. But for the pro side, see MIEK and the Overhead Wire. Also check out Ryan Avent, who writes about the economics of rail almost daily. Tory Gattis writes more skeptically, although I don't think he's dogmatic. For hard-core opposition, there is the Antiplanner. There are many others, of course, and I don't mean to
sleight slight anyone.
My big-picture thoughts:
1. One "duh": Rail should only be built when a cost-benefit analysis warrants. (It's warranted in New York City, not warranted in McComb, Mississippi; the hard cases are the cities in between.) This doesn't mean that rail should be required to pay its own way. Since highways are underpriced, pricing rail at marginal cost would be inefficient. Since there are subsidies all around, I don't think it's helpful to argue about which mode of transportation gets the most subsidy.
2. Mobility is a good thing. Cars provide more mobility than rail -- unless, that is, the roads are overly congested and cannot feasibly be widened or congestion priced. When estimating the demand for rail along a congested route, it is important to count not only the actual vehicle trips, but the vehicle trips never taken because of the congestion. The trips lost due to congestion are the main deadweight loss from congestion.
3. Rail really does foster dense development along routes because, unlike buses, it represents a more or less permanent commitment by the city. For this reason, it increases property values along the route. One could argue that if the net increase in property value exceeds the cost of construction, the rail ought to be built.
4. High-speed rail. I suspect it's cost-justified in the northeast (especially if airport landing rights were priced properly), and probably along the congested San Diego-San Francisco corridor. I don't know about Texas. I would benefit tremendously from high-speed rail; I fly to Dallas or Houston several times a month and rail would make me much more productive. I just don't know whether that marginal increase in productivity would offset the billions and billions in cost.
5. Austin. I don't think light rail from downtown to the airport is worth much. I won't take it because when I get back to Austin after a day-long deposition in Houston, I want to drive directly home. I think most other business travelers will be like me. Tourists: perhaps not, although I think they'll have to get a car anyway.
I think Cap Metro's commuter rail will be a bust for the reasons MIEK has been arguing for years.
Light rail. I imagine a light rail line from South Congress to downtown, past the state government complex, and up Guadalupe to the Triangle would work. South Congress, downtown, and West Campus are rapidly densifying. The congestion will get much worse, or, more precisely, reach an equilibrium in which lots of trips are forsaken. Getting from downtown to UT is already a big hassle; I'm regularly deterred from making the trip. (I voted for the 2000 light rail plan. If I'm going to shell out for a light rail line, though, I'd want it to go down South Lamar, too.)
Buses. I like them. And I ride them. I get a little bit of exercise, plus I don't like to drive. I think Cap Metro needs to increase frequency of service on the busy routes.
Those are my big-picture thoughts, for what they're worth.