Amtrak presented its 30-year plan for high-speed rail in the northeast corridor between Washington, D.C., and Boston. The plan will cost $120 billion. It will take 30 years to complete. It would shrink the travel time between D.C. and New York to 90 minutes. And it would, in theory, triple Amtrak's ridership.

Sure, I can hear the snickers. Judging from its track record in timeliness, 30 years in Amtrak-time is a geological epoch in human time. The absence of a funding plan will also draw conservative criticism. But remember that the Highway Act, spurred by a $25 billion federal check, took decades to complete and today it provides a backbone for commuter infrastructure and interstate commerce.

High-speed rail makes the most sense where large, dense populations live in clustered mega-tropolises that do business with each other. In other words, there's no more logical case for HSR than in the Wash-Bos corridor, connecting DC, Baltimore, Philly, NYC, Providence, Boston, and the smaller cities sprinkled in between. After all, look at Acela, a brilliantly popular northeast medium-speed rail that now collects more than half of Amtrak's total revenue.

The main problem for the Wash-Bos crowd is the cost of building a dedicated high-speed line through this part of the country. The northeast corridor is really busy, which makes it really prosperous, which makes its land really expensive to purchase, which makes it expensive to develop and build a railroad through. Then you've got construction regulations designed to protect green space and local property laws. As Amtrak noted in its plan:

It is important to note that virtually all of the alignments considered pose a variety of construction and environmental challenges. It was beyond the scope of this study to analyze all potential alignments in significant detail.

For metro futurists, HSR is a heart-throb, and I think deservedly so. But getting from here to the future will be a headache for builders and developers.