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Tilting trains are trains the upper part of which, where the passengers are seated, can be tilted sideways. In a curve to the left, it tilts to the left to compensate for the centrifugal push to the right, and conversely. The train may be constructed such that Inertia l forces themselves cause the tilting, commonly referred to as Passive Tilt , or it may be actively induced by a Computer -controlled mechanism, referred to as Active Tilt . RATIONALE Aeroplanes and bicycles simply tilt in place; but automobiles and railway trains cannot do this on their own. To make their turns easier, the roadway of a high-speed highway or railway is canted inward around the curve. To a passenger in such a vehicle, the outward centrifugal force is countered by an inward gravitational one, thus removing the discomfort. (It should be noted that vehicles with high centers of gravity rounding very sharp curves at very high speeds may in fact topple over altogether; banking would also be the answer to counteract this threat. However, since passenger comfort becomes an issue at much lower speeds and gentler curves, railway designers, having kept their passengers comfortable, do not need to worry about trains overturning.) The particular angle of tilt ("superelevation") is determined by the speed at which it is intended that vehicles will pass — faster speeds require more banking. But with a growing desire in the , building its TGV , avoided the problem by building a special new rail network for the high-speed trains which minimized curves, likewise Japan 's Bullet Train and many other high speed lines have necessitated new infrastructure. Other countries, with less elbow room, weaker governmental planning powers, and more hilly terrain, were unable to follow. Specifically, Spain 's national railway RENFE took a domestic invention, the TALGO , and developed it into a reliable high speed train for a low traffic density railway; British Railways (the UK state railway) invested heavily in tilting train technology to overcome the limitations of a rail network constructed through built-up areas early on in railway history when running speeds were very slow; and Italian State railways has invested heavily in tilting technology to speed trains through Italy's mountainous terrain. Even though tilting trains are meant to help reduce the effects of centerfugial force on the human body, tilting trains can still cause Nausea to anyone as they do not reduce the Coriolis Effect on balancing systems. HISTORY TALGO The first tilting trains were the TALGO trains of Spain , developed in the 1930s as a lightweight, fast train using passive tilt. The TALGO is still in production in their 21st generation. TALGO trains are in service in various parts of Europe, and built under licence in Latin America and Asia. In North America, Amtrak uses TALGO trainsets in its Cascades service in the US Northwest, having earlier experimented with them in the Northeast Corridor . Turbo The first tilting train to enter into regular service in North America was the United Aircraft Turbo train, used by Canadian National Railways , in 1969. Plagued with frequent breakdowns of its turbine powerplants, it nevertheless assured daily service between Montréal and Toronto until it was retired in 1984, having been replaced by Bombardier LRC trains. United Aircraft Turbos were also used by Amtrak between Boston and New York in the early 1970s. The UAC Turbo was inspired by the TALGO , and had a Passive Tilt mechanism; its ride quality was rather mediocre due to the use of single axle trucks (bogies) between the cars. Pendolino Another tilting train to enter into regular service was the Pendolino . The original ETR 401 train was built by FIAT in 1975 for the Italian State Railways following a prototype in 1970 and ran successfully for many years. The Pendolino project ticked over on a low budget developing a hypothetical successor until the early 80s when the go ahead was given to build a new fleet, which was the ETR 450 . Later developments of this train ( ETR 460 and ETR 480 ) have been very successful and are used throughout Europe. Advanced Passenger Train In the 1970s and 80s , following the success of its InterCity 125 , British Rail built a tilting train called the Advanced Passenger Train . The APT-E (E for experimental) was powered by gas turbines and the APT-P (P for prototype) was electric. The train was advanced in both name and nature. Not only did it tilt, it had hydro-dynamic brakes, it was articulated and it had two power cars in the centre of the train The latter was necessary because the use of a "buzz bar" to send the 25kV supply along the train and thus allow the power cars to be placed at the ends of the consist was not acceptable at that time. Due to all this complexity the train was never reliable enough to go into service and so the project was scrapped, although the project was purchased by the Pendolino group to enlarge their technology portfolio. During tests some passengers reported that the tilting motion made them nauseous. Subsequently it was learned that this could be prevented by reducing the tilt slightly, so that there was still some sensation of cornering. Much of the technology developed for the power cars was subsequently used in the InterCity225 (Class 91) trains which run on the East Coast route from London to Leeds and Edinburgh. Light, Rapid, Comfortable Canada's contribution is the LRC (Light, Rapid, Comfortable) train, built by Bombardier . This train is rather conventional, having separable carriages instead articulated trailers, and whose it can be intermingled with conventional non-tilt cars. In the United States, Amtrak experimented with the LRC in 1980, but retired it a few years later. In Canada, it entered service in 1981, and the carriages remain in use today. The LRC tilt-mechanism is power-assisted, driven by accelerometers. The ride quality is very smooth, even on relatively low-end tracks. Bombardier have since used updated versions of the LRC carriages are for Amtrak 's Acela Express and the experimental JetTrain . Deutsche Bahn 403 class Another early train with tilting technology was ). An attempt was made to use tilting technology to improve speeds on the extremely twisting Rhine Valley route. Shortly after the train went into service, the tilting technology was disabled as many passengers experienced motion sickness due to sudden and heavy tilting. InterCity Neigezug Switzerland got its first tilting train ever in its territory (discounting the Cisalpino , which entered Switzerland in 1996 ) on May 28 , 2000 . The ICN (''InterCity Neigezug'', or InterCity Tilting Train) entered service, running first from Geneva via Biel / Bienne and Zürich to St. Gallen . It was a major carrier in the national exhibition Expo.02 . TECHNOLOGY Many of the problems with motion sickness are related to the fact that a traditional servo system cannot respond instantaneously to the change in trajectory forces, and even slight discrepancies whilst not being noticeably perceivable cause nausea due to their unnatural nature. The original ETR 401 used individual gyroscopes in each carriage so there was inevitably a lag, even though nausea had not been a major problem with this train. The APT was supposed to supersede this problem by using gyroscopes at the ends of the train and a master slave control system which defined a "tilting curve" for the whole train. It would appear that the technology of the era was not able to implement this technique as well as required. Modern tilting trains have the blessing of the latest signal processing technology which reads the line ahead and is able to anticipate a very precise control signal to the individual carriages and complaints about nausea have become a thing of the past. Some tilting trains run on Narrow-gauge lines. In Japan there are many narrow-gauge lines in mountainous regions, and tilting trains have been designed to run on these. In Australia the link between Brisbane and Cairns by the QR Tilt Train , which uses tilting trains, now claims to be the fastest narrow-gauge link in the world, running at 160km/h. TILTING TRAINS AROUND THE WORLD Trains with tilting by inertial forces:
Trains with tilting controlled by accelerometers:
Trains with tilting controlled by a computer:
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