Indian Railways aims to implement the first stretch of the Maglev project in less than three years’ time. Swiss Maglev pioneer, BHEL in talks for Indian journey
New Delhi: Moving ahead with the introduction of the high-speed Maglev (magnetic levitation) trains in the country, the Indian Railways has asked Rail India Technical and Economic Service (RITES) to prepare a detailed project report within the next six months. The railways aims to implement the first stretch of the project in less than three years’ time.
“We would be very closely associated with RITES as they would collect all the required data after which we would together do the analysis of the sufficiently high clientele sectors where Maglev can be implemented,” said Nitin Chowdhary, Executive Director, Mechanical Engineering (Development), Ministry of Railways.
Maglev trains which run at a minimum speed of 350 km per hour (kmph) and maximum 500kmph without touching the ground are based on the magnetic levitation technology wherein the train is elevated 1 to 6 inches above the ground through a system of magnets thereby making the train move frictionless at high speeds.
The project would be implemented on a PPP (public-private partnership) basis as a joint venture between the railways and a private company wherein the railways would contribute 26% of the equity.
“Two private companies can also form a JV within themselves but the resultant JV would have to in turn work with us in a joint venture by sharing the technology for the project and not be our competition instead,” explained Chowdhary.
According to Chowdhary, the objective is to have a core incubator group with a mandate to develop Maglevs in India. The group will brainstorm with the industry as well as the railways. The close knit group will also oversee the development of the Evacuated Tube Transport (ETT) for freight which would run along the Maglev trains.
Refuting the notion that Maglev would be too expensive a project to generate positive returns, Chowdhary said, “Developing Maglevs won’t be as expensive as people are thinking it to be since we have spoken to a lot of vendors about it and it seems doable.”
He added that for people the priority has shifted towards saving time and if Maglev can provide that with high-end quality service, then passengers will be willing to spend a higher fare amount.
In September this year, six companies, including Bharat Heavy Electricals Ltd and Switzerland-based SwissRapide AG, had evinced interest in developing Maglevs in India. The railways had invited expressions of interest for Maglev trains in July this year. One of the world’s foremost maglev firms – the Zurich-based SwissRapide and the country’s leading electrical systems major Bharat Heavy Electricals Ltd (BHEL) are in talks to work jointly on urban rail projects based on magnetic levitation (maglev).
Maglev is a transport system in which trains glide above a track, supported by magnetic repulsion and propelled by a linear motor, and move at speeds of upto 500 kilometres per hour. Aida Von Schulman, Managing Director (Business Development) of SwissRapide said, “We are now in the process of establishing a partnership with BHEL, within the intent to approach the Ministry of Railways to start the feasibility study for an airport to city centre link project in Kolkata, Chennai or Hyderabad.”
Incidentally, both SwissRapide and BHEL are among the six firms that answered the Railway ministry’s call for Expressions of Interest for Maglev-based Ultra High-Speed Rail Systems in September this year.
SwissRapide is currently building the 135-km high-speed line linking Bern, Zurich and Zurich International Airport using Maglev technology, with line speeds planned at over 550 kmph. The start of commercial operations of the SwissRapide Express is planned for the end of 2017. It is also working on an ultra high-speed line between capital cities of Finland and Estonia, Helsinki and Tallinn respectively, christened FinEst Link.
BHEL is an old hand in the field of railway power systems and has built several of the country’s train motors and locomotives. According to Schulman, the calling card for the Maglev system could be reduced costs – compared to other forms of conventional high-speed rail systems, commonly called as bullet trains – in the longer run.
“Since SwissRapide Ultra-Highspeed Maglev Rail is generally twice as fast point-to-point than conventional high-speed rail, for most service levels, our Maglev rail then only requires single track construction, thus reducing the cost of Maglev up to 30 per cent lower than conventional high-speed rail. Also, since our maglev rail is twice as fast as conventional rail, only half as many trains are required, which also reduces the overall costs,” Schulman said in her email reply.
The firm plans to introduce the same kind of technology that powers the 30-km Shanghai Maglev Transrapid which has been tested to 505 kmph but uses 430 kmph as its cruising speed. It has travelled over 30 million kilometres, since its commissioning in January 2004.
About Maglev Trains
Maglev (derived from magnetic levitation) is a transport method that uses magnetic levitation to move vehicles without making contact with the ground. With Maglev, a vehicle travels along a guideway using magnets to create both lift and propulsion, thereby reducing friction by a great extent and allowing very high speeds.
Maglev trains move more smoothly and more quietly than wheeled mass transit systems. They are relatively unaffected by weather. The power needed for levitation is typically not a large percentage of its overall energy consumption; most goes to overcome drag, as with other high-speed transport. Maglev trains hold the speed record for trains.
Compared to conventional trains, differences in construction affect the economics of Maglev trains, making them much more efficient. For high-speed trains with wheels, wear and tear from friction from wheels on rails accelerates equipment wear and prevents high speeds. Conversely, Maglev systems have been much more expensive to construct, offsetting lower maintenance costs.
Germany, Japan and the U.S. started to develop Maglev transport system in the 1970s, with the aim of improving the capacity and efficiency of their public transport.
Despite decades of research and development, only three commercial Maglev transport systems are in operation, while one more is under construction. In April 2004, Shanghai’s Transrapid system began commercial operations. In March 2005, Japan began operation of its relatively low-speed HSST “Linimo” line in time for the 2005 World Expo. In its first three months, the Linimo line carried over 10 million passengers. South Korea became the world’s fourth country to succeed in commercializing Maglev technology with the Incheon Airport Maglev beginning commercial operation on February 3, 2016.
High-speed transportation patents were granted to various inventors throughout the world. Early United States patents for a linear motor propelled train were awarded to German inventor Alfred Zehden. The inventor was awarded U.S. Patent 782,312 (14 February 1905) and U.S. Patent RE12,700 (21 August 1907). In 1907, another early electromagnetic transportation system was developed by F. S. Smith. A series of German patents for magnetic levitation trains propelled by linear motors were awarded to Hermann Kemper between 1937 and 1941. An early Maglev train was described in U.S. Patent 3,158,765, “Magnetic system of transportation”, by G. R. Polgreen (25 August 1959). The first use of “Maglev” in a United States patent was in “Magnetic levitation guidance system” by Canadian Patents and Development Limited.
As for radiation caused by Maglev rails, the electro-magnetic radiation inside Maglev train carriages is subject to the same limits as radiation in underground carriages. At the same time, compared with underground railways, mid-speed Maglev trains consume less energy, cost less, and can be constructed more quickly.
In the public imagination, “Maglev” often evokes the concept of an elevated monorail track with a linear motor. Maglev systems may be monorail or dual rail and not all monorail trains are Maglevs. Some railway transport systems incorporate linear motors but use electromagnetism only for propulsion, without levitating the vehicle. Such trains have wheels and are not Maglevs. Maglev tracks, monorail or not, can also be constructed at grade (i.e. not elevated). Conversely, non-Maglev tracks, monorail or not, can be elevated too. Some Maglev trains do incorporate wheels and function like linear motor-propelled wheeled vehicles at slower speeds but “take off” and levitate at higher speeds.
The two notable types of Maglev technologies are:
- Electromagnetic suspension (EMS), electronically controlled electromagnets in the train attract it to a magnetically conductive (usually steel) track.
- Electrodynamic suspension (EDS) uses superconducting electromagnets or strong permanent magnets that create a magnetic field, which induces currents in nearby metallic conductors when there is relative movement, which pushes and pulls the train towards the designed levitation position on the guide way.
Another technology, which was designed, proven mathematically, peer-reviewed, and patented, but is, as of May 2015, unbuilt, is magnetodynamic suspension (MDS). It uses the attractive magnetic force of a permanent magnet array near a steel track to lift the train and hold it in place. Other technologies such as repulsive permanent magnets and superconducting magnets have seen some research.
In electromagnetic suspension (EMS) systems, the train levitates above a steel rail while electromagnets, attached to the train, are oriented toward the rail from below. The system is typically arranged on a series of C-shaped arms, with the upper portion of the arm attached to the vehicle, and the lower inside edge containing the magnets. The rail is situated inside the C, between the upper and lower edges.
Magnetic attraction varies inversely with the cube of distance, so minor changes in distance between the magnets and the rail produce greatly varying forces. These changes in force are dynamically unstable – a slight divergence from the optimum position tends to grow, requiring sophisticated feedback systems to maintain a constant distance from the track, (approximately 15 millimetres (0.59 in)).
The major advantage to suspended Maglev systems is that they work at all speeds, unlike electrodynamic systems, which only work at a minimum speed of about 30 km/h (19 mph). This eliminates the need for a separate low-speed suspension system, and can simplify track layout. On the downside, the dynamic instability demands fine track tolerances, which can offset this advantage. Eric Laithwaite was concerned that to meet required tolerances, the gap between magnets and rail would have to be increased to the point where the magnets would be unreasonably large. In practice, this problem was addressed through improved feedback systems, which support the required tolerances.
Electrodynamic Suspension (EDS)
In electrodynamic suspension (EDS), both the guideway and the train exert a magnetic field, and the train is levitated by the repulsive and attractive force between these magnetic fields. In some configurations, the train can be levitated only by repulsive force. In the early stages of Maglev development at the Miyazaki test track, a purely repulsive system was used instead of the later repulsive and attractive EDS system. The magnetic field is produced either by superconducting magnets (as in JR–Maglev) or by an array of permanent magnets (as in Inductrack). The repulsive and attractive force in the track is created by an induced magnetic field in wires or other conducting strips in the track. A major advantage of EDS Maglev systems is that they are dynamically stable – changes in distance between the track and the magnets creates strong forces to return the system to its original position. In addition, the attractive force varies in the opposite manner, providing the same adjustment effects. No active feedback control is needed.
However, at slow speeds, the current induced in these coils and the resultant magnetic flux is not large enough to levitate the train. For this reason, the train must have wheels or some other form of landing gear to support the train until it reaches take-off speed. Since a train may stop at any location, due to equipment problems for instance, the entire track must be able to support both low- and high-speed operation.
Another downside is that the EDS system naturally creates a field in the track in front and to the rear of the lift magnets, which acts against the magnets and creates magnetic drag. This is generally only a concern at low speeds (This is one of the reasons why JR abandoned a purely repulsive system and adopted the sidewall levitation system.) At higher speeds other modes of drag dominate.
The drag force can be used to the electrodynamic system’s advantage, however, as it creates a varying force in the rails that can be used as a reactionary system to drive the train, without the need for a separate reaction plate, as in most linear motor systems. Laithwaite led development of such “traverse-flux” systems at his Imperial College laboratory. Alternatively, propulsion coils on the guideway are used to exert a force on the magnets in the train and make the train move forward. The propulsion coils that exert a force on the train are effectively a linear motor: an alternating current through the coils generates a continuously varying magnetic field that moves forward along the track. The frequency of the alternating current is synchronized to match the speed of the train. The offset between the field exerted by magnets on the train and the applied field creates a force moving the train forward.
The term “Maglev” refers not only to the vehicles, but to the railway system as well, specifically designed for magnetic levitation and propulsion. All operational implementations of Maglev technology make minimal use of wheeled train technology and are not compatible with conventional rail tracks. Because they cannot share existing infrastructure, Maglev systems must be designed as standalone systems. The SPM Maglev system is inter-operable with steel rail tracks and would permit Maglev vehicles and conventional trains to operate on the same tracks. MAN in Germany also designed a Maglev system that worked with conventional rails, but it was never fully developed.
|Each implementation of the magnetic levitation principle for train-type travel involves advantages and disadvantages.|
|EMS (Electromagnetic suspension)||Magnetic fields inside and outside the vehicle are less than EDS; proven, commercially available technology; high speeds (500 km/h (310 mph)); no wheels or secondary propulsion system needed.||The separation between the vehicle and the guideway must be constantly monitored and corrected due to the unstable nature of electromagnetic attraction; to the system’s inherent instability and the required constant corrections by outside systems may induce vibration.|
|EDS (Electrodynamic suspension)||Onboard magnets and large margin between rail and train enable highest recorded speeds (603 km/h (375 mph)) and heavy load capacity; demonstrated successful operations using high-temperature superconductors in its onboard magnets, cooled with inexpensive liquid nitrogen.||Strong magnetic fields on the train would make the train unsafe for passengers with pacemakers or magnetic data storage media such as hard drives and credit cards, necessitating the use of magnetic shielding; limitations on guideway inductivity limit maximum speed; vehicle must be wheeled for travel at low speeds.|
|Inductrack System (Permanent Magnet Passive Suspension)||Failsafe Suspension—no power required to activate magnets; Magnetic field is localized below the car; can generate enough force at low speeds (around 5 km/h (3.1 mph)) for levitation; given power failure cars stop safely; Halbach arrays of permanent magnets may prove more cost-effective than electromagnets.||Requires either wheels or track segments that move for when the vehicle is stopped. Under development (as of 2008); No commercial version or full scale prototype.|
The German Transrapid, Japanese HSST (Linimo), and Korean Rotem EMS maglevs levitate at a standstill, with electricity extracted from guideway using power rails for the latter two, and wirelessly for Transrapid. If guideway power is lost on the move, the Transrapid is still able to generate levitation down to 10 km/h (6.2 mph) speed, using the power from onboard batteries. This is not the case with the HSST and Rotem systems.Neither Inductrack nor the Superconducting EDS are able to levitate vehicles at a standstill, although Inductrack provides levitation at much lower speed; wheels are required for these systems. EMS systems are wheel-free.
EMS systems such as HSST/Linimo can provide both levitation and propulsion using an onboard linear motor. But EDS systems and some EMS systems such as Transrapid levitate but do not propel. Such systems need some other technology for propulsion. A linear motor (propulsion coils) mounted in the track is one solution. Over long distances coil costs could be prohibitive.
Earnshaw’s theorem shows that no combination of static magnets can be in a stable equilibrium.Therefore a dynamic (time varying) magnetic field is required to achieve stabilization. EMS systems rely on active electronic stabilization that constantly measures the bearing distance and adjusts the electromagnet current accordingly. EDS systems rely on changing magnetic fields to create currents, which can give passive stability.
Because Maglev vehicles essentially fly, stabilisation of pitch, roll and yaw is required. In addition to rotation, surge (forward and backward motions), sway (sideways motion) or heave (up and down motions) can be problematic.
Superconducting magnets on a train above a track made out of a permanent magnet lock the train into its lateral position. It can move linearly along the track, but not off the track. This is due to the Meissner effect and flux pinning.
Some systems use Null Current systems (also sometimes called Null Flux systems). These use a coil that is wound so that it enters two opposing, alternating fields, so that the average flux in the loop is zero. When the vehicle is in the straight ahead position, no current flows, but any moves off-line create flux that generates a field that naturally pushes/pulls it back into line.
Some systems (notably the Swiss metro system) propose the use of vactrains—Maglev train technology used in evacuated (airless) tubes, which removes air drag. This has the potential to increase speed and efficiency greatly, as most of the energy for conventional Maglev trains is lost to aerodynamic drag.
One potential risk for passengers of trains operating in evacuated tubes is that they could be exposed to the risk of cabin depressurization unless tunnel safety monitoring systems can repressurize the tube in the event of a train malfunction or accident though since trains are likely to operate at or near the Earth’s surface, emergency restoration of ambient pressure should be straightforward. The RAND Corporation has depicted a vacuum tube train that could, in theory, cross the Atlantic or the USA in ~21 minutes.
Energy for Maglev trains is used to accelerate the train. Energy may be regained when the train slows down via regenerative braking. It also levitates and stabilises the train’s movement. Most of the energy is needed to overcome “air drag”. Some energy is used for air conditioning, heating, lighting and other miscellany.
At low speeds the percentage of power used for levitation can be significant, consuming up to 15% more power than a subway or light rail service. For short distances the energy used for acceleration might be considerable.
The power used to overcome air drag increases with the cube of the velocity and hence dominates at high speed. The energy needed per unit distance increases by the square of the velocity and the time decreases linearly. For example, 2.5 times more power is needed to travel at 400 km/h than 300 km/h.
Comparison with conventional trains
Maglev transport is non-contact and electric powered. It relies less or not at all on the wheels, bearings and axles common to wheeled rail systems.
- Speed: Maglev allows higher top speeds than conventional rail, but experimental wheel-based high-speed trains have demonstrated similar speeds.
- Maintenance: Maglev trains currently in operation have demonstrated the need for minimal guideway maintenance. Vehicle maintenance is also minimal (based on hours of operation, rather than on speed or distance traveled). Traditional rail is subject to mechanical wear and tear that increases exponentially with speed, also increasing maintenance.
- Weather: Maglev trains are little affected by snow, ice, severe cold, rain or high winds. However, they have not operated in the wide range of conditions that traditional friction-based rail systems have operated. Maglev vehicles accelerate and decelerate faster than mechanical systems regardless of the slickness of the guideway or the slope of the grade because they are non-contact systems.
- Track: Maglev trains are not compatible with conventional track, and therefore require custom infrastructure for their entire route. By contrast conventional high-speed trains such as the TGV are able to run, albeit at reduced speeds, on existing rail infrastructure, thus reducing expenditure where new infrastructure would be particularly expensive (such as the final approaches to city terminals), or on extensions where traffic does not justify new infrastructure. John Harding, former chief Maglev scientist at the Federal Railroad Administration, claimed that separate Maglev infrastructure more than pays for itself with higher levels of all-weather operational availability and nominal maintenance costs. These claims have yet to be proven in an intense operational setting and does not consider the increased Maglev construction costs.
- Efficiency: Conventional rail is probably more efficient at lower speeds. But due to the lack of physical contact between the track and the vehicle, Maglev trains experience no rolling resistance, leaving only air resistance and electromagnetic drag, potentially improving power efficiency. Some systems however such as the Central Japan Railway Company SCMaglevuse rubber tires at low speeds, reducing efficiency gains.
- Weight: The electromagnets in many EMS and EDS designs require between 1 and 2 kilowatts per ton. The use of superconductor magnets can reduce the electromagnets’ energy consumption. A 50-ton Transrapid Maglev vehicle can lift an additional 20 tons, for a total of 70 tons, which consumes 70-140 kW. Most energy use for the TRI is for propulsion and overcoming air resistance at speeds over 100 mph.
- Weight loading: High speed rail requires more support and construction for its concentrated wheel loading. Maglev cars are lighter and distribute weight more evenly.
- Noise: Because the major source of noise of a Maglev train comes from displaced air rather than from wheels touching rails, Maglev trains produce less noise than a conventional train at equivalent speeds. However, the psychoacoustic profile of the Maglev may reduce this benefit: a study concluded that Maglev noise should be rated like road traffic, while conventional trains experience a 5–10 dB “bonus”, as they are found less annoying at the same loudness level.
- Braking: Braking and overhead wire wear have caused problems for the Fastech 360 rail Shinkansen. Maglev would eliminate these issues.
- Magnet reliability: At higher temperatures magnets may fail. New alloys and manufacturing techniques have addressed this issue.
- Control systems: No signalling systems are needed for high-speed rail, because such systems are computer controlled. Human operators cannot react fast enough to manage high-speed trains. High speed systems require dedicated rights of way and are usually elevated. Two Maglev system microwave towers are in constant contact with trains. There is no need for train whistles or horns, either.
- Terrain: Maglevs are able to ascend higher grades, offering more routing flexibility and reduced tunneling.
Comparison with aircraft
Differences between airplane and Maglev travel:
- Efficiency: For Maglev systems the lift-to-drag ratio can exceed that of aircraft (for example Inductrack can approach 200:1 at high speed, far higher than any aircraft). This can make Maglev more efficient per kilometer. However, at high cruising speeds, aerodynamic drag is much larger than lift-induced drag. Jets take advantage of low air density at high altitudes to significantly reduce air drag. Hence despite their lift-to-drag ratio disadvantage, they can travel more efficiently at high speeds than Maglev trains that operate at sea level.
- Routing: While aircraft can theoretically take any route between points, commercial air routes are rigidly defined. Maglevs offer competitive journey times over distances of 800 kilometres (500 miles) or less. Additionally, Maglevs can easily serve intermediate destinations.
- Availability: Maglevs are little affected by weather.
- Safety: Maglevs offer a significant safety margin since maglevs do not crash into other maglevs or leave their guideways.
- Travel time: Maglevs do not face the extended security protocols faced by air travelers nor is time consumed for taxiing, or for queuing for take-off and landing.
The Shanghai maglev demonstration line cost US$1.2 billion to build. This total includes capital costs such as right-of-way clearing, extensive pile driving, on-site guideway manufacturing, in-situ pier construction at 25 metre intervals, a maintenance facility and vehicle yard, several switches, two stations, operations and control systems, power feed system, cables and inverters, and operational training. Ridership is not a primary focus of this demonstration line, since the Longyang Road station is on the eastern outskirts of Shanghai. Once the line is extended to South Shanghai Train station and Hongqiao Airport station, which may not happen because of economic reasons, ridership was expected to cover operation and maintenance costs and generate significant net revenue.
The South Shanghai extension was expected to cost approximately US$18 million per kilometre. In 2006 the German government invested $125 million in guideway cost reduction development that produced an all-concrete modular design that is faster to build and is 30% less costly. Other new construction techniques were also developed that put Maglev at or below price parity with new high-speed rail construction.
The United States Federal Railroad Administration, in a 2005 report to Congress, estimated cost per mile of between $50m and $100m. The Maryland Transit Administration (MTA) Environmental Impact Statement estimated a pricetag at US$4.9 billion for construction, and $53 million a year for operations of its project.
The proposed Chuo Shinkansen Maglev in Japan was estimated to cost approximately US$82 billion to build, with a route requiring long tunnels. A Tokaido maglev route replacing the current Shinkansen would cost 1/10 the cost, as no new tunnel would be needed, but noise pollution issues made this infeasible.
The only low-speed Maglev (100 km/h or 62 mph) currently operational, the Japanese Linimo HSST, cost approximately US$100 million/km to build. Besides offering improved operation and maintenance costs over other transit systems, these low-speed Maglevs provide ultra-high levels of operational reliability and introduce little noise and generate zero air pollution into dense urban settings.
As more Maglev systems are deployed, experts expected construction costs to drop by employing new construction methods and from economies of scale.
The highest recorded maglev speed is 603 km/h (375 mph), achieved in Japan by JR Central’s L0 superconducting Maglev on 21 April 2015, 28 km/h (17 mph) faster than the conventional TGVwheel-rail speed record. However, the operational and performance differences between these two very different technologies is far greater. The TGV record was achieved accelerating down a 72.4 km (45.0 mi) slight decline, requiring 13 minutes. It then took another 77.25 km (48.00 mi) for the TGV to stop, requiring a total distance of 149.65 km (92.99 mi) for the test. The MLX01 record, however, was achieved on the 18.4 km (11.4 mi) Yamanashi test track – 1/8 the distance. No Maglev or wheel-rail commercial operation has actually been attempted at speeds over 500 km/h.