Site:           Railway Technical Research Institute (RTRI)
                Maglev System Development Department
                Yamanashi Maglev Test Line
                2-8-38 Hikari-cho, Kokubunji-shi
                Tokyo 185, Japan
                http://www.rtri.or.jp/
Date Visited:   23 June 1996
WTEC Attendees: D. Gubser (report author), 
                D. Larbalestier, 
                M. Suenaga
Hosts:          Fuminao Okumura, Deputy General Manager, 
                   Planning Division, 
                   Maglev System Development Department, 
                   Railway Technical Research Institute
                Shoichi Hashimoto, Director of Engineering, 
                   Chief of Construction Office, 
                   Railway Technical Research Institute, 
                   Yamanashi Test Line Construction Office

BACKGROUND

Japan's national superconducting Maglev (magnetic levitation) project aims to produce high speed (550 km/hr) commercial ground transportation in the 21st century. The Maglev project began in 1962 with testing of linear induction propulsion; in 1972 the first experimental superconducting Maglev test vehicle was operated; by 1979, a test vehicle attained a top speed of 517 km/hr at the Miyazaki Test Track; and in 1987 a two-car manned unit attained a speed of 400 km/hr on the same test track. Also in 1987, the Railway Technical Research Institute (RTRI) was formed as a research foundation and took over the research and development work for the Japanese Railway (JR) system. The Yamanashi Maglev test line, located in Yamanashi Prefecture, about 2-2.5 hours west of Tokyo by train or expressway, was approved for construction in 1989 with management by RTRI and JR.

The Yamanashi test line is the first section of a new high speed railway, the Chuo Shinkansen line, that is being constructed between Tokyo and Osaka, inland from the present coastal Shinkansen line. When completed, this section will be 42 km in length, 80% in tunnels, with a maximum incline of 4%. It will cost $3.4 billion. The initial construction is 18.4 km in length and was to be completed in 1997.

The 550 km/hr speed of the superconducting Maglev compares with the 350 km/hr of the fastest Japanese train today; 250 km/hr for the Shinkansen (bullet) trains; and 450 km/hr for the projected top speed of the German Maglev train. The German magnetic levitation work uses permanent magnets (not superconducting), and magnetic attraction forces (North to South poles) with active feedback control for stability, versus the magnetic repulsion (North to North poles) of the superconducting version, which produces intrinsically stable operation. The German version is in a more advanced state of development, but the Japanese superconducting version will attain a higher speed, will travel with a greater train/track separation (8-10 cm vs. 1-2 cm), and will be quieter in operation -- all important features that keep the Japanese fully committed to the longer term development of their superconducting Maglev. Cryogenics is not an issue with the Japanese Maglev project.

PRINCIPLE OF OPERATION

At the heart of the Maglev system are the superconducting magnets used to levitate, guide, propel, and brake the train (Fig. Maglev.1). Levitation is caused by magnetic repulsion between the on-board superconducting coils (race track design, 5.3 tesla at the Nb-Ti coil windings) and the magnetic fields induced in nonsuperconducting track coils (figure-8 design) located on the sides of the U-shaped track. The figure-8 design provides stability to the train motion by balancing against both up and down motion. At equilibrium, the superconducting coils pass the figure-8 coils at the midpoint or crossover of the figure 8. No net circulating current is induced in the figure-8 coils in this case. If the train falls below the midpoint, induced currents are set up in the track coils, creating a repelling force from the bottom half of the figure-8 loop, and an attractive force from the top half of the loop (and verse versa if the train were to rise above the equilibrium point). Currents are induced in the track coils by the moving superconducting coils, and levitation begins after the train reaches a speed of 100 km/hr. For lower speeds, wheels are used. Guidance is provided by the same magnetic forces that repel the train from the track coils. Since the track coils are located on the sides of the track, induced currents from sideways motion repel the train if the train moves closer to that side. Propulsion is provided by linear induction where an ac magnetic field propagates down the track on a separate set of coils and pulls the superconducting magnets on the train if the phase is ahead of the train (acceleration) or retards the motion if the phase is behind the train (braking).

Fig. Maglev.1. Coil systems.

TRAIN SPECIFICATIONS

The cars on the Maglev have slightly smaller dimensions than the present high speed Shinkansen train in order to improve air resistance, and they are considerably (30%) lighter. To reduce the weight on the train as much as possible, the cars have aluminum alloy bodies, and even the seats are constructed of a lightweight composite structure. The outer skin will be shaped in a futuristic design to minimize aerodynamic drag and reduce noise -- two front end designs are being tested. One design, manufactured by Mitsubishi Heavy Industries (MHI), has a "double cusp" feature that looks much like a duck's bill; the other design, manufactured by Kawasaki Heavy Industries (KHI), has a wedge-shaped nose. A decision on which design is better will be made after test runs on the Yamanashi test line.

A three-car train (77.6 meters long, 2.9 meters wide, and 3.3 meters high) has been constructed by MHI, KHI, and Nippon Sharyo, Ltd., at a cost of $55 million. The cars carry almost the same number of passengers as the present Shinkansen train. The superconducting coils are located between cars so as to reduce passengers' exposure to the magnetic field. Iron shielding will be used to further reduce the field to a level of about 20 gauss in the intercar passageway and much less in the passenger compartments. The train will "fly" with an 8 cm to 10 cm separation between the track and the body of the train.

The Maglev train will not have an on-board driver. Cameras located at the front of the train and fiberoptic cabling relay all information back to the control room, where operation is monitored and computer-controlled by a sophisticated traffic control system. Operators are currently conducting simulated train test runs in the control room to determine optimum operational parameters.

TESTING

The 18.5 km track will test/demonstrate several key aspects of the high speed Maglev transportation system:

• high speed runs at 500 km/hr with safety and comfort
• reliability and durability of vehicle and ground facility and equipment, including the SC magnets
• structural standards specifying a minimum radius of curvature and steepness of gradients
• distance between track axes, taking account of two trains passing each other (approach speeds of 1,000 km/hr)
• vehicle performance related to tunnel cross-section and the pressure fluctuations in the tunnel
• turnout performance
• environmental conservation
• multiple train traffic control system
• operation and safety system and maintenance standards
• control system between substations
• economy of construction and operation

Simulations of many of these tests were already underway at the time of the WTEC team's visit, affording training of control room operators. Actual testing was to begin in 1997.

ISSUES

The two largest issues for the Maglev project are (1) construction cost and (2) projected ridership. Costs of a Maglev line are about 50% greater than those of the high speed Shinkansen track. The largest cost item is the track rails. Advanced designs are being considered to reduce the number of coils and the amount of copper in the track coils. Similarly, alternative construction techniques are being used to minimize construction costs. The issue of ridership is simply a matter of trying to estimate the passenger traffic between Tokyo and Osaka in the future with both the Shinkansen line and the Maglev line being operative. The Maglev line will reduce the transit time from 2½ to 1½ hours, but the cost of a ticket will undoubtedly be more expensive.

ASSESSMENT

The Maglev project is a national project and is unique to Japan. Major construction of a commercial track is underway, and the project is funded for the next three years to complete the 42 km track. There appear to be no technical barriers to completing the Maglev project, although construction cost is still an issue. No one is predicting the future of the project after three years, but this author expects that if the economy improves, the project will continue to expand, and more track will be constructed. The completion date for opening the new high speed transportation line is far in the future, and the WTEC panel's hosts were unwilling to predict a completion date, even if all goes well. An estimate of 2030 to 2050 would perhaps be a realistic guess for beginning commercial operation of a superconducting Maglev train.

A fallback position should the Maglev prove to be too expensive is to convert the track to a conventional Shinkansen line. There is a definite commitment to a second high speed rail line, regardless of type, to provide alternative routes in case of major disruptions in one route. Thus, the new line will continue to be built. National pride and past development of the superconducting Maglev train make the future look promising for this application of superconducting technology. This project is a prime example of the Japanese long term vision and commitment to advanced technology.