Electricity and magnetism will propel the future transportation system, and it will make our travel safe, smooth, but faster than other conventional transport system. The new transportation technology is magnetic levitation or Maglev, and in this transportation technology, the train remains suspended and move in the air freely without any support but, under a strong electromagnetic field. The speed of maglev vehicles can be between 300 to 500 kmph. The technology is based on the familiar property of magnets that the opposite poles attract and same poles repel. For example, the north pole of a magnet will attract the South Pole of other magnet and repel the similar pole. So, it is possible that a magnet can remain suspended in air over the strong magnetic field of another magnet.
A permanent magnet has fixed magnetic field, but the field strength of an electromagnet can be increased either by varying the current or by increasing the number of turns in the coil, so, initially the electromagnets were preferred in maglev design to ensure greater field strength. The new concept of transportation is therefore based on the common behaviour of the electromagnets and their magnetic field strength.
In maglev transportation, the current from an electrical source magnetise the levitation coil and produce a strong magnetic field to lift the train off the track, and electromagnetic propulsion move the car along the guideway freely without friction. The guideway structure is the main element in maglev rail because it directs the vehicle, support the load of the vehicle. Linear motor is the most common propulsion used in the maglev transportation system and operates like a rotational electric motor but, it is stretched out horizontally instead of being wrapped in a cylinder. (Stewart, J., 2012)
The technology to use the electromagnetic force in transportation has already attracted the interest of many countries because, it is much higher energy efficient, faster than the other modes of transport, less expensive, effective to cut down the demand of fossil fuel, reduce air pollution, and congestion in road traffic. (Jordan, J., 2008)
The three prime functions of maglev technology are levitation, propulsion and guidance and basic elements of maglev are the vehicle and guideway. The levitation of train is caused either due to attractive or repulsive force between the magnets mounted on the train and the electromagnets in the track or guideway. Vehicle paths in EMS and in EDS system are called guideway and track respectively. (Yaghoubi, H., 2013)
So, in almost all the applications, the maglev technology applies either the attractive force or the repulsive force of magnets for levitation of the train. Suspension on the attractive force of two magnetic fields is electromagnetic suspension (EMS) and on the repulsive force is electro-dynamic suspension (EDS). Germany and Japan have already tested and implemented their maglev project, suspension system in Germany makes use of EMS and Japan uses the EDS maglev. (Balestreire, M., & Hollenberger, J., 2005)
Electromagnetic suspension (EMS): Conventional electromagnets are used in this suspension and arranged at the bottom of the maglev. An alternating current through the electromagnets of the train and the ferromagnetic guideway, and consequently produce a strong magnetic field. The electromagnets of the train and the magnetised guideway attract each other and this attractive force levitate the train off the track and propel to move the train without track contact or without friction by maintaining a significant distance between the train and guideway. In this system the interlocking between the carriage and the guideway prevent the train to derail and make it easy to travel steep uphill. Constant power supplies are required to the electromagnets to keep the train off the track even at rest, so, the EMS maglev needs no auxiliary wheels to rest on and an emergency battery power supplies are provided to deal with a sudden power failure.
Electro-dynamic suspension (EDS): In this suspension, superconducting magnets (SCM) at very low temperature are placed at the bottom of maglev train to ensure better flow of current, to prevent energy loss due to heat generation, and to attain greater magnetic field. In maglev system, when the superconducting magnets on board pass through the levitation coils, an induced current is generated in the coil, and the induced current produce induced magnetic field. The generated magnetic field of the train and levitation coil repel each other, and lift the train off the track. The EDS is much stable in the suspension category, because, the restoring force generated due to repulsion between levitation coil and SCM keep the train aligned, and it is easy to carry heavier loads without affecting the minimum distance between the train and the track. In a sudden power failure the superconducting magnets continue to levitate the train till the critical speed of levitation, and the train can come to rest on Auxiliary wheels.
Maglev vehicles can be configured for different modes, and for both high speed and low speed transportation. Low speed is suitable for short distance travel and high speed vehicles are used for long distance travel. However the electrical equipments of the passengers require to be shielded from the strong electromagnetic field generated by the superconducting magnets.
The maglev runs on electricity and magnetism and it needs no other fuel. Initially the maglev will cost very high for the infrastructure development but, in the long run it will be reduced to very low and at the same time the reduction in fuel demand for running maglev is a very important aspect for the sustainability of this transportation.(Balestreire, M., & Hollenberger, J., 2005)
The proposed project of the underground version of maglev train is Swissmetro, it will run in a speed of 200 kmph under normal air pressure and by reducing the air pressure the train will run in much higher speed up to 600 kmph. (Swiss Metro: Travel below the alps in a Subway-Torpedo., n.d.)
Indutrack is a new approach in maglev design that requires no levitation power for a moving train. To levitate the train in motion, neodymium-iron-boron (NdFeB) permanent magnets are mounted on the train in Halbach Array, the arrangement induces the current in the track coil, and the track coils produce an induced electromagnetic field of strong repulsive force in respect to the permanent magnets. When the train is at rest there is no levitation and the train is supported by auxiliary wheels. So, the arrangement of permanent magnets in Halbach Array has added more efficiency in Indutrack than the EMS and EDS, it is more economic because, it has eliminated the necessity of expensive cryogenic technology for cooling the superconducting magnets in EDS, and in a sudden power failure the train slow down on their own and lower the levitation with the decreasing speed.
The Indutrack could provide the boost for future rocket launch program of NASA. In future, the Maglev launching system would accelerate a space shuttle up to 600 mph speed without the use of any on board fuel, and due to this reason weight of a rocket will be much less than the conventional rockets.
So, in the Advanced Space Transportation program of NASA, the Maglev technology would propel the future space shuttles, and take a spacecraft along a track with better safety and reliability, and at significantly low cost for per pound of pay load. (Advanced Space Transportation Program: Paving the Highway to Space, n.d.)
The maglev transportation system is cost effective, economic, and by shortening the travel time the transportation system reduced the energy consumption. In future, the widespread implementation of maglev in public transport for different distances can save considerable energy consumption, and able to add more comfort and safety in the journey to be a part of a major mode of transport in everyday life.
Reference:
Advanced Space Transportation Program: Paving the Highway to Space. (n.d.). Retrieved October 16, 2014, from http://www.nasa.gov/centers/marshall/news/background/facts/astp.html_prt.htm.
A new approach for magnetically levitating trains and rockets. (n.d.). Retrieved October 18, 2014, from https://str.llnl.gov/str/Post.html.
Balestreire, M., & Hollenberger, J. (2005, April 9). Maglev: Transportation of the future. Retrieved October 19, 2014, from http://www.askmar.com/Inductrack/2005-04-09 Maglev Transportation of Future.pdf.
Bonsor, K. (n.d.). How Maglev Trains Work. Retrieved October 19, 2014, from http://science.howstuffworks.com/transport/engines-equipment/maglev-train1.htm.
Jordan, J. (2008, November). Amtrak: A Crucial Component in America’s Transport Future. Retrieved October 17, 2014, from http://www.limba.net/catalogimages/maglevamtrak.pdf.
Stewart, J. (2012, May 6). Maglevs: The floating future of trains. Retrieved October 19, 2014, from http://www.bbc.com/future/story/20120504-the-floating-future-of-trains.
Swiss Metro: Travel below the alps in a Subway-Torpedo. (n.d.). Retrieved October 19, 2014, from http://www.articlesextra.com/swiss-metro-alps-tunnel.htm.
Yaghoubi, H. (2013, February 19). The Most Important Maglev Applications. Retrieved October 19, 2014, from http://www.hindawi.com/journals/je/2013/537986/.
