Amtrak’s latest Next-Generation High-Speed Rail plan is now up to $151 billion, from a prior cost of $117 billion. This is partially a small cost escalation, but mostly including Master Plan upgrades to the legacy line. Per kilometer of route length, this means the project has now crossed the $200 million/km mark, a higher cost than 60%-underground Chuo Shinkansen maglev. The primary cause of the high cost of Amtrak’s project is the heavy amount of deep-cavern urban tunneling: nearly a tenth of the cost is the Gateway Tunnel, a rebranded bundling of ARC into the project, and a similar amount is a similar project in Philadelphia. At least this time they’re serving Rhode Island with a stop in or near Providence rather than Woonsocket.

In contrast with this extravaganza, it is possible to achieve comparable travel times for about one tenth the cost. The important thing is to build the projects with the most benefit measured in travel time reduced or reliability gained per unit of cost, and also share tracks heavily with commuter rail, using timed overtakes to reduce the required amount of multi-tracking.

I propose the following general principles, guiding any future development in the corridor:

1. Rolling stock is cheaper than infrastructure. This is not true everywhere, but the Northeastern US and Japan both have high infrastructure-to-equipment cost ratios. A Shinkansen train today costs about $4 million per car judging by how much Taiwan pays. A 16-car train every 15 minutes from Washington to Boston, with a one-way travel time including turnaround of about 3:30, would require 30 sets, or 480 cars, or $2 billion. Therefore, it makes financial sense to demand more of the rolling stock: some tilting as present on the Talgo, Pendolino, N700, or E5; high initial acceleration as present on the N700-I; and high power-to-weight ratio as on the Talgo and Shinkansen models, or even possibly an all-cars-powered Pendolino.

The difference between an average and a top-rate train could easily amount to 20 minutes between Washington and Boston. Making up those 20 minutes with infrastructure, once the easiest projects have been completed, would cost far more than $2 billion.

2. Speed up commuter trains instead of bypassing them. The place where this is most obvious and useful is the Boston-Providence segment. I have nothing to add that I didn’t already say in my pair of posts on the subject last year. Something similar is true between Baltimore and Washington. It is more difficult between New York and New Haven, but at least there are curves that have to be bypassed anyway, and so the track sharing can be reduced to a manageable degree given the line’s heavy commuter traffic.

This requires fixing agency turf battles, which costs a lot of political capital but is almost free to the taxpayer. In contrast, long multi-track segments, often with new viaducts, easily run into the billions. Amtrak’s single biggest question mark east of New York is the string of tunnels from Penn Station to New Rochelle to Danbury, all so that it doesn’t have to share tracks with Metro-North. It could buy the commuter operations and subsidize them forever and still come out ahead of all those tunnels.

3. The regulations should be based on service needs. As a corollary of #1 and 2 and the every minute counts philosophy they espouse, the regulations should allow trains that can operate safely. Here safety is determined by actual practice and track record, rather than what the FRA thinks safety is, which has an incidental relationship with reality. That Shinkansen trains do not meet UIC standards should not be even a minor issue; trains in Japan are safer than in the UIC’s prime-mover European countries.

4. On shared segments that aren’t bypassed, build infrastructure that allows higher speeds. This is a corollary of #2: if legacy routes are to be upgraded rather than bypassed, there’s no point in assuming present-day speed limits, such as Metro-North’s 75 mph/120 km/h limit in Connecticut, will remain in place, and therefore projects should be built with high radius of curvature. Assume that large portions of the New Haven Line will host trains going at 240 km/h.

5. Make sure station throats allow full speed. Every non-geometric restriction on speed – tunnel diameter, track condition, switches – should be eliminated. Higher-speed switches are cheaper than new concrete pouring; more precise track maintenance is cheaper than most people realize, standing at about $100,000 per double-track-km on average; Shinkansen trains’ noses are designed (and European trains’ noses can be modified) to allow full speed through narrow tunnels, as Shinkansen construction standards minimize tunnel diameter to reduce costs.

The time cost of even a short segment inhibiting full-throttle acceleration in station throats is higher than most people realize. A kilometer a train has to wend at 50 km/h when it could go 200, such as the Penn Station throat, is worth 54 seconds. At stations closer to full-speed zone, this speed-restricted kilometer slows the train’s acceleration to full speed further down the line, and thus it comes at the expense of a kilometer at 300-360 km/h, raising the time cost even further.

6. Fix curves in higher speed zones. This applies mainly to the S-curve flanking I-287 in Metuchen: its curvature is not terrible, but because to its south there are no geometric speed restrictions for tens of kilometers and to its north the curves are also reasonably gentle, its bang for the buck can be surprisingly high.

7. Worry about track capacity when all other capacity factors have been optimized. An intercity railroad that runs 8-car trains is definitionally not at capacity. Running 16-car trains requires lengthening a small number of platforms, most at easy locations. Doubling train capacity across the Hudson chokepoint requires building a new tunnel under the river. Amtrak currently runs 4 trains per hour into Penn Station at the peak; if after everything else has been built it has exhausted the capacity of 4 trains per hour each with 16 cars and a thousand seats, its operating profits will let it pay for any further expansion.

With the above seven principles, one could come up with a reasonable set of projects of immediate significance. With a total cost in the single-digit billions, they’d eliminate most of the barriers to full-speed travel between New York and Washington, and leave New York-Boston with just one major problem section between Stamford and Milford. Best-practice trains, even ones optimized for a straighter route – for example, Shinkansen or the Talgo, but not the Pendolino, which is both heavier and less powerful but has a much larger degree of tilting – could go from Boston to Washington in about 4 hours, or not much more.

Getting this further down to 3 hours would require further investment according to the same principles, but even 4 hours, by virtue of the markets to and from New York, would generate the profits required to pay for them. Moreover, the contrast between fast travel on bypass segments in eastern Connecticut or straight legacy segments in Rhode Island and New Jersey and the remaining slower problem segments would create political will to complete the system. The areas with the most NIMBY resistance should be left for last, because today’s train riders as well as Amtrak itself are not nearly as powerful as they will be if the mostly NIMBY-free projects cut train travel time from 7 hours to 4.