Maglev vs. high-speed rail

First of all, there is no point of using a maglev in the city, since its technical advantages are substantial only at high speeds and high distances (inter-city travel). There is simply no space in a city to reach the speed and the full potential of the maglev. So, let's compare it to the corresponding existing mode of the intercity surface travel - conventional high-speed rail. The reasons there is only one maglev line in commercial service on this planet are very different from what many people usually think they are. There are a couple of major advantages of the conventional high-speed rail, often overlooked when discussing potential maglev projects.

The main advantage of the high-speed rail is its compatibility with all those thousands of kilometers of the conventional rail already built. For instance, a conventional high-speed train can operate on the dedicated high-speed rail, but it can also operate on a slower regular section equally well. This is typical, for instance, in France, where TGV trains run not only on the dedicated lines, but also on the conventional railroads with lower speeds. This allows for much wider network with direct service and for gradual growth of the high-speed portion of that network with time. For maglev, only what you built is where your trains can run, but nowhere else. As is with any other transit mode, it is an issue of the transportation SYSTEM, which is all too often ignored when people speak about the maglev. Transportation should not be viewed on a line-by-line basis, it is always a system, and thinking of the system integration is often more important than any particular preferences for a short segment of a particular line.

Besides this major network issue, there is a technical one.

Imagine a conventional high-speed train running at 300 km/h. Now imagine something happened and the electricity got cut off, say, a blackout occurred, like the one in New York a few years ago. What will happen to the train? Well, pretty much nothing: it will continue to roll on the rails before it stops.

Now, think of a maglev LEVITATING about 1 cm above the rail. It is being held up in the air by the electromagnetic field. It is also moving, say, at 300 km/h. Now, imagine the electricity got cut here too, for some weird reasons beyond control of the operating company. The electricity is cut, the electromagnetic field disappears, and the train crushes onto the rail at the speed of 300 km/h. Do you think 1 cm is a small distance? Well, this distance at 300 km/h will be more than enough to cause a major catastrophe. If one surface moves with respect to another at 300 km/h and suddenly they get into contact, a major accident with multiple life losses is almost guaranteed. Think of a high-speed train accidentally "touching" a wall on its side. The effect is the same.

Do you see my point? There is an important difference between the maglev and the conventional high-speed rail. A conventional train is not suspended in the air depending 100% on the electricity - it is standing on rails at all times, and as long as the rails are structurally sound, nothing is going to happen if the power supply is cut. This is not true for maglev. Cut the power, and the maglev train falls on the track. Taking into account possible high speeds involved, this "minor" fall means a major crash. A system failure on many transportation modes is nowhere as drastic as the one for the levitating train. Even for a plane - if a dispatcher is cut off and there is a blackout in the airport, the plane does not directly depend on anything happening on the ground and can land somewhere else. Maglev depends 100% of the reliability of the entire line, not only mechanical reliability (like the ordinary rail) but also electrical reliability. The many-fold redundancy is needed for maglev systems, far exceeding any other form of transportation and thus making it more expensive compared to any other modes.

Last update: October 14, 2006.