Last decade’s excitement about the prospect of high-speed rail in the United States gave way to disappointment over project cancellations and mounting costs. Instead of conventional high-speed rail (where trains run at 200 miles per hour), several ventures have come forth with proposals to build new, even faster technologies, such as magnetic levitation (maglev) and underground vacuum tubes (Hyperloop). These proposals would operate very high-speed trains separate from the conventional rail network. But are these technologies really a good fit for D.C. and the rest of the Northeastern United States? There are reasons for skepticism.

You might have heard of Hyperloop, the brainchild of Tesla Motors and SpaceX CEO Elon Musk, which promises to run trains at airplane speeds through vacuum-sealed tubes. But despite fawning press coverage, Hyperloop would need to clear some major technological and practical barriers to become reality: Musk’s original idea was riddled with technical errors, and the more serious attempt by Hyperloop One to build a working demonstration has only been able to match the speed of high-speed rail. Aside from the technical challenges, the service still has serious practical problems to grapple with, such as securing the vacuum tubes against vandalism or terrorism.

Maglev is a more interesting proposition.  Though the main progress is currently happening in Japan, a U.S.-based company supported by the Central Japan Railway Company (JR Central) is pitching JR Central’s SCMaglev technology for a Baltimore-Washington line, which it claims would connect the two cities in 15 minutes. [Note: This paragraph originally stated that Siemens was the company involved. The article has been corrected to reflect this change.]

Japan has had a conventional high-speed rail network since 1964, called the Shinkansen (also known as the “bullet train.”) It was the busiest high-speed rail network in the world until China recently overtook it, but its passenger density remains higher than that of the Chinese network. With the Tokyo-Osaka line aging and nearing capacity, private operator JR Central is investing in a parallel maglev line, called the Chuo Shinkansen, to open in stages between 2027 and 2037.

Unlike Hyperloop, however, JR Central’s maglev technology has been extensively tested. JR Central began research into this technology in 1963 and opened a short test track in 1977, and after privatization began more intensive commercial testing in 1997, on a test track to be incorporated into the Chuo Shinkansen. The planned commercial top speed is around 314 miles per hour, well below the maximum achieved in tests. (There is also a short orphaned line in Shanghai, using technology owned by Siemens.)

However, while maglev is both technically feasible and safe, it is not a good fit for the economic and geographic needs of the Washington region, or for the Northeast Corridor in general. Maglev would not provide a very large reduction in door-to-door travel time even if it could serve central locations, such as D.C.’s Union Station or New York’s Penn Station. Moreover, serving such locations in the first place is inherently more difficult than on conventional rail, which could increase costs considerably. Finally, whereas more or less any conventional train can run on any conventional track, maglev is vendor-locked: the two well-tested systems in the world, Siemens’ system and JR Central’s system, are incompatible, which would increase costs even further.

The relationship between speed and distance

The higher top speeds that these new rail technologies promise is most useful on long-distance lines with trips that would originally take multiple hours. This is because super-fast rail speeds won’t actually save passengers that much time for shorter trips, such as the trip from D.C. to Baltimore.

Think of it this way: People travel between their home and their ultimate destination (such as a hotel), and not just between train stations. Therefore, the full trip time includes both access time at the home end and egress time at the destination end.

For example, people who live in Tenleytown need about half an hour to reach Union Station by Metrorail, and would probably leave 40 or 45 minutes before the train’s scheduled departure time, to cushion against delays on Metrorail. At the other end, they might need to spend another 20 minutes traveling from the train station, such as Baltimore Penn Station or New York Station, to their ultimate destination. This additional travel time—somewhat more than an hour—is independent of train speed.

If the total access and egress time is an hour, then increasing the speed of the train has diminishing returns beyond a certain point. Reducing the travel time of a train from three hours to an hour and a half through high-speed rail means reducing door-to-door travel time from four hours to two hours and a half, a sizable reduction. But then reducing train travel time further from an hour and a half to 45 minutes means reducing door-to-door travel time to 1:45, a noticeable but not game-changing improvement.

The travel times described above are for New York-Washington trips. But for closer-in connections, faster trains save even less time. The Acela Express connects Washington and Baltimore in half an hour today, whereas JR Central says maglev would do the same trip in 15 minutes. While a 15-minute trip time between Washington and Baltimore sounds like a game changer, in reality, the total trip time (including travel to and from the stations) is likely to be more like 1:15, down from 1:30 today—only a minor improvement.

This is why the maglev line under construction in Japan aims at fairly long distances. The plan is to connect Tokyo and Osaka in a little more than an hour, down from two and a half hours by the Shinkansen today. This line is planned to open in segments due to its high construction cost, but the first segment, Tokyo-Nagoya, is much closer in distance to the New York-Washington trip than Baltimore-Washington. Today, the Shinkansen connects Tokyo with Nagoya in an hour and a half, and the under-construction maglev train will cut this to 40 minutes. There are no plans to open intermediate segments between Tokyo and some of its suburbs, because at such a short distance, maglev provides too little of a time benefit for the cost of construction and operations.

Within the U.S., maglev could be useful for longer segments. New York-Washington might be feasible as part of a longer line connecting the Northeast with Charlotte, Atlanta, and Miami. A line between New York and Chicago would also be useful: the two cities are about 800 miles apart by high-speed rail, a trip that a conventional high-speed train could do in about five hours but that maglev could do in three, which would be competitive with air travel. (In Japan, Shinkansen trains connecting cities in three or three and a half hours have a 70 percent share of the market with airlines, but for trips that take five hours their share drops to 10 percent.)

However, committing to building such a long maglev line means committing to spending a very large up-front investment . A maglev line connecting New York, Washington, and Atlanta could be successful, but would require 800 miles of construction. Could such a line be built at reasonable cost? The answer is probably not, and the reason has to do with the “last mile” problem and other challenges of urban construction.

The “last mile” problem

The most difficult infrastructure construction is in urban areas. As the United States was building its rail network in the 19^th century, the First Transcontinental Railroad opened in 1869, but the first connection across Baltimore only opened in 1873—and the first connection across New York didn’t open until 1910, with Penn Station.

Today, the situation is much the same. Outside urban areas, infrastructure construction can take advantage of available rights-of-way along power line corridors, Interstate highways, and railroads. High-speed tracks, especially maglev, must have gentle curves, but it’s usually not that difficult to use exurban land for their necessary sweeping turns. But in urban areas, land is expensive and the only way to build new rights-of-way involves tunneling.

To avoid tunneling, most high-speed railroads in the world use low-speed railroad tracks for the last few miles into major cities. France has the busiest and most extensive high-speed rail network in Europe, the TGV; while TGV lines allow trains to run at 186-200 miles per hour nearly the entire way, the last few miles into Paris and the major secondary cities are on slow legacy track, often shared with commuter trains and low-speed intercity trains. This way, no tunnels are needed except in mountainous areas.

Leveraging existing urban rail approaches to reduce costs is not possible on maglev, which is technologically incompatible with conventional rail. As a result, the Chuo Shinkansen needs to tunnel under the entire Tokyo urban area to reach Central Tokyo. A total of 90 percent of the Tokyo-Nagoya segment will be in tunnel, driving up construction costs, which currently stand at $90 billion for just 255 miles. As a design compromise, JR Central does not reach Tokyo Station, but terminates at Shinagawa, a secondary business district located a few miles out.

In the Northeastern United States, every big city has conventional rail approaches from both sides. Conventional high-speed rail could run to Union Station from the north and continue south to Virginia, and could also make use of existing approaches to Philadelphia 30th Street Station and New York Penn Station. The tunnels to New York are crowded—Amtrak would like to add new tunnels in the Gateway Program—but there is capacity in the existing tunnels today for a long high-speed train every 15 minutes replacing Amtrak’s current service. Maglev could not use existing approaches in the same way; it would need new tunnels under all the major cities of the Northeast, driving up costs.

Vendor lock-in

The last mile problem would increase the cost of civil infrastructure for maglev. But the cost of the technology itself is likely to be elevated as well, because of the problem of vendor lock-in.

Rail tracks are an old technology from the 19th century, but essentially an open one: any train that meets the required clearances can run on them. A rail operator that wishes to buy new trains can procure them from a large number of vendors based in Europe or East Asia; small changes in specs based on local conditions are routine and easy to accomplish. Even more advanced rail technology has multiple vendors: European Train Control System (ETCS) is an open standard that’s increasingly common throughout Europe as well as in much of the rest of the world, with several competing conglomerates manufacturing compatible systems for high-speed and legacy conventional rail.

No such standard exists for maglev. Siemens’ Transrapid system generates magnetic levitation in an inherently different way from JR Central’s system; if the United States installs the JR Central system in the Northeast and is dissatisfied with the technology, it will not be able to simply switch to Siemens. Without the pressure of competition, it is likely that either maglev operator would overcharge American states for its system, making large profits at the expense of the American public.

The situation is different domestically within Japan, as JR Central owns its maglev technology. But everyone else facing the decision of whether to buy proprietary maglev technology or multi-vendor high-speed rail using ETCS signaling should consider the fact that ETCS has ample competition and maglev does not.

For fast trips to Baltimore, conventional high-speed rail wins out

Maglev remains risky, based purely on the fact that it would require commitment to a proprietary technology belonging to a private company. However, it could still potentially be a useful option on some long routes where airplanes typically win out over ground transportation today, including New York-Chicago and New York-Miami. But the route most important to the District in this case—the connection to New York—is too short, and the Baltimore-Washington route that has also been discussed is so short it would not justify even conventional high-speed rail by itself.

For these shorter routes, there’s a stronger case for conventional high-speed rail. The Northeast Corridor has good legacy track alignments into the big cities. A conventional high-speed solution would be able to use this existing infrastructure in ways that maglev could not; relatively little investment would be required within the District, where infrastructure is the most expensive.

In fact, the Northeast Corridor is so replete with good legacy rights-of-way that any cost-efficient solution would need to incorporate Amtrak and conventional rail. The best solution is to commit to making the current system work, upgrading it to high-speed rail standards but maintaining its fundamental characteristic as a mixed system using shared tracks in land-constrained city centers. If the cost of such an endeavor is too high, the cost of maglev is yet higher. If maglev belongs in the U.S., it belongs on other corridors, and quite possibly it belongs in another half-century.

Feature image: The Shanghai Maglev Train in 2012 (Source: “Maglev” by maxtm, licensed under CC BY 2.0)