Because it's not about how fast you can get somewhere, it is about how far you can go in a given time.
Some of the promoters of the Hyperloop like to say “We’re selling time”. But Emily Badger, writing in the New York Times, reminds us of the very important point that in fact, they are selling space. That’s because every time technology evolves and provides faster transportation, people naturally spread out.
When you give people greater speed, they don’t use it to save time; they use it to consume more space. As a result, cities have spread outward as transportation technology has evolved. Horse-drawn carriages enlarged pedestrian towns. Streetcars enabled streetcar suburbs. Highways made exurbia possible.
It all comes down to how far you can get in 30 minutes. There is even a general law about it, knowns as Marchetti’s constant.
Mr. Marchetti noted supporting historical clues: Ancient Rome, Persepolis and Marrakesh were about five kilometers across, or the maximum distance most people can travel in an hour on foot. He diagramed the growth of Berlin, which appeared to expand concentrically as transportation advances enlarged the land people could cover.
So what happens when the Hyperloop or other technology can take you hundreds of miles in 30 minutes?
Philadelphia and Washington could become linked the way Manhattan and Brooklyn are today, if the travel costs are comparable (recall, before approval of the New York subway, that the two boroughs were separate cities).
You don’t need a Hyperloop either, just high quality fast trains like the Shanghai mag-lev. Then you get from New York to Washington in about the same time it takes to subway from Times Square to the Barclays Center in Brooklyn.
Badger then looks at what self-driving cars or autonomous vehicles do the the picture. She wonders, “If a car becomes a traveling office, will people even mentally measure their commutes as 'travel time'?” I suspect that the AV will be less like an office and more like a living room, and it will render the concept of commute time meaningless.
In either scenario, the result is probably the same: endless sprawl. When it comes to housing, the next generation will probably Hyperloop ‘till they qualify.