In early January 2022, a prototype mag- lev train was rolled out in southwest China’s city of Chengdu, one of the latest developments in magnetic levitation trains. The domestically developed locomotive uses high temperature superconducting and will travel with a designed speed of 620 km/h, according to Southwest Jiaotong University, one of the train’s designers. Maglev trains, levitated from the tracks and propelled by powerful magnets to avoid wheel-rail friction, are de- signed to break the speed bottlenecks facing high-speed trains.
The floating maglev train has a long history, and developing the revolutionary technology does not go as frictionless as the trains float over the tracks. What are some of the most notable maglev projects in history, and what is the status of maglev trains today?
The repelling force of magnets
To make a vehicle float, the repelling force of magnets is an intuitive way. To create the required magnetic field, electromagnets, or permanent magnets, are attached to the underside of the vehicle. This is a dynamic system because when the magnets installed in the train move along coils of wire arranged on the guideway, electric currents are generated within the coils. These induction currents, in turn, produce magnetic fields that repel the magnets in the train. This magnetic flux allows the train to float. A disadvantage of this technology is that the magnetic field is only generated when the vehicle is moving fast enough to produce the required induction current.
Another option is to attach a curved construction to the underside of the train that embraces the guideway. At both ends of the C-shaped arm, there are electromagnets, which exert an attraction on the magnetic material at the bottom of the guideway. An advantage of this electromagnetic suspension approach is that with this technology, hovering always works, even when the train is stationary.
The first commercial maglev project
The world’s first commercial magnetic levitation transport system was launched in the UK in Birmingham on August 16, 1984. Three fully automatically controlled low- speed trains were in operation, floating at a height of 15 millimeters and a maximum speed of 42 kilometers per hour above the track between Birmingham airport and the nearby intercity station. The six-meter vehicles in question each had six seats and 34 standing places. The weight of the three- meter-high vehicles, including passengers, was eight tons in total.
However, the transport system suffered several setbacks. For example, one of the companies involved had decided at one point that the bottom of the maglev vehicle was too weak. This led to the vehicle being reinforced with an extra layer of fiberglass. However, this increased the weight of the already relatively heavy vehicle to such an extent that the electromagnets could no longer keep the train afloat. Another issue was that the conventional speedometers did not work because there was no contact with the concrete guideway. By 1995, there was no choice but to discontinue the maglev.
The Berlin M-Bahn
Between 1989 and 1991, the inhabit- ants of Berlin could use the M-Bahn, also known as Magnetbahn. The line was 1.6 kilometers long, and there were three stations: Kemperplatz, Bernburger Platz and Gleisdreieck. The floating train operated at a cruising speed of 80 kilometers per hour. Originally, the M-Bahn was to start operating in May 1987, but a terrorist attack on April 18, 1987, disrupted the planning. A second attack at Kemperplatz station was foiled by the security service at the last moment.
In the meantime, however, an important event took place, which the initiators of the M-Bahn could hardly have foreseen— the fall of the Berlin Wall on November 9, 1989. The event completely changed the local transport concept; it now made more sense to restore the U-Bahn, which used to run between Gleisdreieck and Potzdamer Platz before the construction of the Wall, for the route of the M-Bahn to become part of the U2 line. The demolition of the M-Bahn began two months after its official opening in July 1991 and was completed in February 1992.
In the Netherlands, there were also plans for a maglev route between Schiphol airport and Groningen, but the project team decided in 2006 that the construction would be too expensive.
Six maglev projects in operation
At this moment, six commercial maglev projects are in operation worldwide: two in South Korea, one in Japan and three in China. What is striking is that in five cases, they are low-speed floating trains; only in Shanghai does the maglev reach a high average speed of more than 400 kilometers per hour, an interesting fact because one of the selling points of maglev is the exceptional high speeds it can achieve.
There are also several maglev projects worldwide in preparation. Brazil, for instance, floats an experimental maglev train between two university buildings. In the US, there are plans for a maglev connecting Baltimore and New York City called the Northeast Maglev, among others. In Fenguhuang, China, a low- speed maglev line is under construction, and in Japan, a 286-kilometer-long route be- tween Tokyo and Nagoya is expected to be finished around the year 2027. Thus, in the next decade, maglev trains could gain a more prominent role in the world of transportation.
Rijkert Knoppers studied mechanical engineering at Delft University of Technology and is author of the book Maglev Trains, the Attraction of Levitation.
Image: A maglev train prototype using the high temperature superconducting (HTS) maglev technology is unveiled in Chengdu, southwest China's Sichuan Province, January 13, 2021. /CFP. Credit: CFP
