Transrapid (German: [tʁansʁaˈpiːt] ) is a German-developed high-speed monorail train using magnetic levitation. Planning for the system started in the late 1960s, with a test facility in Emsland, Germany, inaugurated in 1983. In 1991, technical readiness for application was approved by the Deutsche Bundesbahn in cooperation with universities. The last version, the 2007-built Transrapid 09, is designed for a cruising speed of 505 km/h (314 mph) and allows acceleration and deceleration of approximately 1 m/s2 (3.6 km/h/s; 2.2 mph/s). In 2002, the first commercial implementation was completed – the Shanghai Maglev Train, which connects the city of Shanghai's rapid transit network 30.5 km (18.95 mi) to Shanghai Pudong International Airport. The Transrapid system has not yet been deployed on a long-distance intercity line. The system was developed and marketed by Siemens and ThyssenKrupp, as well as other, mostly German companies. In 2006, a Transrapid train collided with a maintenance vehicle on the German test track, leading to 23 fatalities. In 2011, the Emsland test track closed down when its operating license expired. In early 2012, demolition and reconversion of the entire Emsland site including the factory was approved, but has been delayed until late 2023 because of concepts for usage as a Hyperloop test track or a maglev track for the Chinese CRRC Maglev. The development of the Transrapid system in Germany has been carried forward in some form by the company Max Bögl, which has developed the Transport System Bögl for short range maglev tracks.
Technology
Levitation The super-speed Transrapid maglev system has no wheels, no axles, no gear transmissions, no steel rails, and no overhead electrical pantographs. The maglev vehicles do not roll on wheels; rather, they hover above the track guideway, using the attractive magnetic force between two linear arrays of electromagnetic coils—one side of the coil on the vehicle, the other side in the track guideway, which function together as a magnetic dipole. During levitation and travelling operation, the Transrapid maglev vehicle floats on a frictionless magnetic cushion with no mechanical contact whatsoever with the track guideway. On-board vehicle electronic systems measure the dipole gap distance 100,000 times per second to guarantee the clearance between the coils attached to the underside of the guideway and the magnetic portion of the vehicle wrapped around the guideway edges. With this precise, constantly updated electronic control, the dipole gap remains nominally constant at 10 millimetres (0.39 in). When levitated, the maglev vehicle has about 15 centimetres (5.9 in) of clearance above the guideway surface. The Transrapid maglev vehicle requires less power to hover than it needs to run its on-board air conditioning equipment. In Transrapid vehicle versions TR08 and earlier, when travelling at speeds below 80 kilometres per hour (50 mph), the vehicle levitation system and all on-board vehicle electronics were supplied with power through physical connections to the track guideway. At vehicle speeds above 80 kilometres per hour (50 mph), all on-board power was supplied by recovered harmonic oscillation of the magnetic fields created from the track's linear stator. (Since these oscillations are parasitic, they cannot be used for vehicle propulsion). A new energy transmission system, version TR09, has since been developed for Transrapid, in which maglev vehicles now require no physical contact with the track guideway for their on-board power needs, regardless of the maglev vehicle speed. This feature helps to reduce on-going maintenance and operational costs. In case of power failure of the track's propulsion system, the maglev vehicle can use on-board backup batteries to temporarily power the vehicle's levitation system.
Propulsion The Transrapid maglev system uses a synchronous longstator linear motor for both propulsion and braking. It works like a rotating electric motor whose stator is "unrolled" along the underside of the guideway; instead of producing torque (rotation) it produces a linear force along its length. The electromagnets in the maglev vehicle which lift it also work as the equivalent of the excitation portion (rotor) of this linear electric motor. Since the magnetic travelling field works in only one direction, if there were to be several maglev trains on a given track section, they would all travel in the same direction thereby reducing the possibility of collision between moving trains.
Energy requirements The normal energy consumption of the Transrapid is approximately 50 to 100 kilowatts (67 to 134 hp) per section for levitation and travel, and vehicle control. The drag coefficient of the Transrapid is about 0.26. The aerodynamic drag of the vehicle, which has a frontal cross section of 16 m2 (172 sq ft), requires a power consumption, at 400 km/h (249 mph) or 111 m/s (364 ft/s) cruising speed, given by the following formula:
P = c w ⋅ A F r o n t ⋅ v 3 ⋅ ( density of surrounding air ) / 2 {\displaystyle P=c_{w}\cdot A_{\rm {Front}}\cdot v^{3}\cdot ({\mbox{density of surrounding air}})/2}
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