Infrastructure is a dull business. The guy talking about pipes and wires is not generally the life of the party (to my chagrin). But infrastructure is all the rage these days, with economists calling for broad stimulus, and Barack Obama’s transition team planning big investments in the American economy.

The excitement seems to be catching. Even staid legislators are feeling energized by the new push to rebuild America. Last week, Senators John Kerry (D-Mass.) and Arlen Specter (R-Penn.) introduced the High-Speed Rail for America Act, a bill that would authorize $23 billion in bond sales to fund rail infrastructure generally, and true high-speed networks (with speeds in excess of 150 mph) in California and the Northeast corridor. If passed it would be the second bill this year to help lay the groundwork for high-speed rail investments.

The arguments in favor of high-speed rail are straightforward and familiar. It’s green. It relieves congestion on highways and at airports. And by improving connections between cities, it boosts economic productivity.

But it’s worth asking about the bigger picture. Is high-speed rail just a shiny new toy for high-rolling businesspeople, or is it a meaningful contributor to the green economy?

Ben Adler asks this question in a recent piece at Campus Progress, saying:

While making the trip from Los Angeles to San Francisco by high-speed rail instead of by flying would save some CO2 emissions, the bigger problem is not that you can’t get from L.A. to San Francisco fast enough by train, it’s that you can’t get around L.A. or San Diego, the nation’s second and eighth largest cities, respectively, without a car…

But the idea of long-distance high-speed rail is primarily of interest to business travelers and the relatively wealthy. The people who need subways, trolleys, and buses to get around the fringes of L.A. are poor and working class. Sure, when the Google gang comes down to L.A. they can take the high-speed train instead of flying, but the housekeepers who commute from East L.A. to Westwood by bus or car won’t see their lives change at all.

Now, this is rather an unfortunate portrayal of the market for inter-city rail; in fact, many lower- and middle-income individuals find themselves needing to travel between cities, and it hardly seems equitable or green to force them to pay to drive or fly. But the bigger story is that investment in high-speed rail is likely to strengthen central cities and increase demand for local transit.

Why? Because high-speed connections between central city terminals increase the return to living and working in central cities. This is crucial. For decades, inter-city transportation has primarily been oriented around automobiles — freeways and airports dropped miles from city centers. Because businesspeople require cars to travel, they own cars. And because they own cars, they often find it inconvenient to live in dense, walkable, centrally located communities.

And this influences the shape of the metropolitan economy. Business corridors grow up around highways and airports, and those job centers continue to attract residents to exurban developments. Given this kind of urban structure, the constituency for transit and the economic utility of transit are somewhat reduced. Sadly, local transit has failed to obtain the funding it deserves because the squeakiest wheels — businesses and suburban, upper-income households — have not seen that funding to be in their interest.

The northeastern corridor of the United States offers the embryo of an alternative. There, a legacy of density, transit, and inter-city rail supports central city economies. This, in turn, helps to support strong central city residential populations and a constituency for local transit spending.

It shouldn’t be any wonder, then, that this corridor is home to some of the most ambitious transit planning around today. Washington and New York are each adding new heavy rail intra-city lines, and streetcar, light rail, and bus investments are planned up and down the corridor. These investments will help grow local economies, and they’ll also provide faster, greener, more convenient transit to those unwilling or unable to purchase a car.

We have to remember that to build healthy, walkable cities we need robust urban economies. And to get those economies we have to make the transportation investments we’ve been unwilling to make in the age of highways. High-speed inter-city rail is an indispensable part of that equation.