Tilting train

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The X 2000 train on a US tour at Union Station, Chicago, Illinois, in 1993. This composite image shows the extent to which the train can tilt in either direction.

A tilting train has a mechanism that enables increased speed on regular railway tracks. As a vehicle rounds a curve at speed, objects inside the train experience centrifugal force. This can cause packages to slide about or seated passengers to feel squashed by the outboard armrest due to its centripetal force, and standing passengers to lose their balance. Tilting trains are designed to counteract this discomfort. Two types are the Italian Pendolino and the Spanish Talgo.

In a curve to the left the train tilts to the left to compensate for the g-force push to the right, and vice versa.

The train may be constructed such that inertial forces cause the tilting (passive tilt), or it may have a computer-controlled power mechanism (active tilt).

Contents

[edit] Rationale

An ICE-T (DB class 411) leaves a curve. Note the different inclinations of the cars.

Aeroplanes and bicycles tilt in place but automobiles and 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 tilt makes the overall acceleration vector act downwards, rather than pushing them to the side, minimising discomfort. Vehicles with high centers of gravity rounding sharp curves at high speeds may topple over, and banking helps counteract this risk.

The particular angle of tilt ("superelevation") is determined by the intended vehicle speed — faster speeds require more banking. But with a growing desire in the 1960s and 1970s to build high-speed rail networks, a problem arose: the amount of tilt appropriate for high-speed trains would be over-tilted for slower-speed local passenger and freight trains sharing the lines. France, building its TGV, avoided the problem by building a new rail network for high-speed trains which minimized curves, likewise Japan's bullet train and other high speed lines have necessitated new infrastructure.

Countries with less land, weaker governmental planning powers or more hilly terrain were unable to follow. 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[citation needed] invested heavily in tilting train technology to overcome the limitations of a rail network in built-up areas, and Italy's Trenitalia has invested heavily in tilting technology to speed trains through mountainous terrain.[1]

Tilting trains are meant to help reduce the effects of centrifugal force on the human body, but they can still cause nausea as they do not reduce the Coriolis effect on balancing systems. The effect could be felt under maximum speed and tilt, when the combination of tilting outside view and lack of corresponding sideways force can be disconcerting to passengers, like that of a "thrill ride". Researchers have found that if the tilting motion is reduced to compensate for 80% or less of lateral force passengers feel more secure.

[edit] History

[edit] Santa Fe Pendulum-suspension car #1100

In 1938 Pullman built for the Atchison, Topeka and Santa Fe Railway an experimental pendulum-suspension "chair" car (coach), which saw service on the San Diegan train among others. Mounted on high springs, the car tilted inwards on curves to counterbalance the cant deficiency with the induced centrifugal force. As it relied on passive components, it was not entirely successful, and the lack of damping produced a sea-sickness inducing rolling motion that doomed the experiment.

[edit] SNCF experiment

In 1956 SNCF experimented with a self-propelled pendulum car, which also relied on centrifugal force. This experiment demonstrated the need for an active suspension system to tilt the coach bodies.

[edit] Talgo

A 1964-era locomotive hauling a Talgo III tilting train.

The first successful European tilting train design was the Talgo in Spain, developed in the 1950s as a lightweight, fast train using passive tilt. The Spanish National Railway, RENFE, adopted the system widely, but was restricted to the Iberian peninsula initially.

The first test of a Talgo in the United States was the John Quincy Adams trainset with Fairbanks-Morse P-12-42 tested by the New York, New Haven and Hartford Railroad in 1957–1958. Due to technical troubles and the precarious financial state of the New Haven railroad, the trainset was set aside. The first full commercial application of passive tilting trains in North America appeared in early 1970s, with the United Aircraft TurboTrain, an adaptation of the second generation of the Talgo. Talgo is currently in its 21st generation of production. 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 trains in its Cascades service in the Northwest.

[edit] UAC TurboTrain

The first tilting train to enter into regular service in North America was the United Aircraft TurboTrain, used by Canadian National Railways, in 1969. Plagued with frequent breakdowns of its turbine power plants, it nevertheless assured daily service between Montreal 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 had a passive tilt mechanism and they inspired the second generation of TALGO trains. Its ride quality was mediocre. Due to the inadequate suspension on the single axle trucks (bogies) between the cars, the tilt system required a direct connection between bogies and coaches. None are currently in use.

[edit] Advanced Passenger Train

Advanced Passenger Train ATP-P pre-production unit

In the 1970s and 1980s, 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 two power cars were deemed necessary for the proposed schedule but the use of a "roof-line" to send the 25 kV 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 full-time service and the project was scrapped, although some aspects of the technology were purchased by the Pendolino group to enlarge its 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) locomotives, which run on the East Coast route from London to Leeds and Edinburgh.

The Economist wrote in its 21 February 1998 issue, "Tilt technology, to be sure, got off to a disastrous start in 1981. That was when British Rail (BR), Britain's old nationalised railway, had to withdraw its so-called Advanced Passenger Train after only three days of scheduled services. Passengers had complained of feeling sick, and there were many technical hitches with brakes and the state-of-the-art suspension. Since that unhappy debut, however, the technology has developed to a point where tilt trains are now being operated throughout Europe."

[edit] Pendolino

A Finnish Pendolino in 2005

Another tilting train to enter 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. The latest development in this line is the ETR 610, which will enter service in Switzerland and Italy (and possibly Germany) in 2007/8 on the Cisalpino routes.

[edit] X 2000

In 1990 Swedish railways introduced a high speed service called X 2000. It uses an active tilting system to be able to run in high speed (200 km/h) on standard track.

[edit] Light, Rapid, Comfortable

VIA Rail Canada LRC

Canada's contribution is the LRC (Light, Rapid, Comfortable) train, built by Bombardier. This train is rather conventional, having separable carriages instead of articulated trailers, and 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 for Amtrak's Acela Express, the third generation of tilting ICE, the new generation of fast British trains (Virgin Super Voyager) and the experimental JetTrain.

[edit] Germany

An ICE TD in regular service in 2002

Deutsche Bahn started tests with tilting trains in Germany with its class 634 in 1967 when some class 624 DMUs were equipped with passive tilting systems. As the passengers experienced motion sickness, the tilting technology was disabled and later removed. The tests continued with the prototypes of the following class 614 units, but due to the again unsatisfying results the serial types were delivered without tilting system.

Another early train with tilting technology was Deutsche Bahn's class 403 (today this number is used by ICE 3) high speed EMU, which entered into service in 1973. Following its InterCity services until 1979, it was also used for airport transfers between Düsseldorf and Frankfurt (see also: AiRail Service). Class 403 was able to tilt 4°, but the fixed pantographs limited this to 2°. Shortly after the train had gone into service the tilting technology was disabled as many passengers experienced motion sickness because the pivotal point was too low.

The next attempt was made with DMUs and the well proven Italian hydraulic active tilting system. Between 1988 and 1990 DB commissioned 20 class 610 units for fast regional traffic. This time the results were quite satisfying and allowed a significant reduction of running times. Class 610 was followed by class 611 which basically was built for the same purpose (fast regional traffic with up to 160 km/h on twisting non-electrified lines). Class 611's tilting system was electric, with a maximum 8° tilt, based on military technology from the Leopard tank. However, after coming into service in 1996 this 50-unit class experienced problems both with the newly-developed tilting system as well as chassis and axles, so it was judged not successful. The tilting system was out of service until 2006, when hardened axles and system updates finally solved the problems. In consideration of these problems DB ordered a full re-engineering, resulting in the development of class 612. Starting in 1998, a total of 192 units were commissioned by DB. The tilting system was reliable, but when in 2004 cracks were detected in a number of wheel sets, again wheels and axles had to be replaced. Today class 612 is back to tilting operation and forms the backbone of DB's fast regional service on non-electrified lines. Additional units were sold to Croatia, where they are used for InterCity services.

Finally in 1999 DB was able to use tilting technology for its InterCityExpress services, when with class 411 and 415 an electric high-speed tilting train was commissioned. While classes 401 to 403 (without tilting technology) were to cover the newly built or modernized high speed lines at up to 300 km/h (class 403), classes 411 and 415 with maximum speed of 230 km/h were designed for older twisting main lines. A total of 60 class 411 and 11 class 415 (shorter version) have been built so far. Both classes worked reliably until late 2008 when cracks were found on an axle during a routine check.[2] The tilting mechanism has been switched off since 23. October 2008[3] and the maintenance intervals were drastically reduced which lead to major service disruptions[4].

Much of the technical layout is derived from the ICE 3. Austria's ÖBB has purchased three units in 2007, operating them jointly with DB for services from Germany to Austria. It might be noteworthy that even though DB assigned the name ICE-T to class 411/415, the T originally did not stand for tilting but for Triebwagen (self-propelled car), as DB's marketing department at first deemed the top speed too low for assignment of the InterCityExpress brand and therefore planned to refer to this class as IC-T (InterCity-Triebwagen).

Rather luckless was class 411/415's adaptation for diesel services. In 2001 a total of 20 units were commissioned for use on the Dresden-Munich line, but these class 605 (ICE-TD) units experienced trouble from the start. After the breaking of an axle in 2002, all remaining 19 units (one fell off a working platform) were taken out of service. Even though one year later the trains were admitted to service again, DB judged their operation the be overly expensive. Today they are used for amplifier trains. Starting end of 2007, it is planned to deploy class 605 on the Hamburg-Copenhagen route.

[edit] TGV Pendulaire

In 1998 SNCF bowed to political pressure (the tilt-train was a credible threat to the TGV dedicated high-speed line network) and put in service an experimental TGV pendulaire. Following the test programme, it was converted back to a TGV-PSE train.

[edit] InterCity Neigezug

The SBB RABDe 500 in 2004

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) was made by Bombardier, including a tilting-system designed by SIG (today ALSTOM). It started service on the line from Geneva via Biel/Bienne and Zürich to St Gallen. It was a major carrier in the national exhibition Expo.02.

[edit] Japan

JR Hokkaidō DC283 DMU

In Japan, the beginning of the usual operation of the tilting train is the operation of limited express Shinano (former name of Nagano) by 381 Series electric multiple unit in Chūō-saisen (central west line) of Japanese National Railways in 1972 . 381 was mass-produced based on data of 591 Series electric multiple unit that had been made for trial purposes in 1969.

Though Japanese National Railways became the Japan Railways Group by being divided in 1987, the concept model of 2000 Series diesel multiple unit of JR Shikoku was produced in 1989, and in 1990 it was introduced (with 2000 Series mass production cars) into limited express Shiokaze (sea breeze) and Nanpū (south wind). The development of new cars (both electric and diesel) are continued, and introduction to new line districts are continued one by one.

Moreover, the first tilting Shinkansen train, the N700 Series electric multiple unit, has been introduced since 2007.

[edit] Technology

Many of the problems with motion sickness are related to the fact that traditional servo systems respond inappropriately to the changes in trajectory forces, and even small errors whilst not being consciously perceivable cause nausea due to their unfamiliar nature. The original Fiat 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 overcome 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 are profiting from state-of-the-art signal processing which senses the line ahead and is able to predict optimal control signals for the individual carriages. Complaints about nausea have become a thing of the past.

Some tilting trains run on narrow gauge railways. In Japan there are many narrow gauge lines in mountainous regions, and tilting trains have been designed to run on these. In Australia the service between Brisbane and Cairns by the QR Tilt Train claims to be the fastest narrow-gauge train in the world, running at 160 km/h.

[edit] Tilting trains around the world

Talgo 350 train as used on Spanish AVE high speed lines
Swedish X2 tilt train

Trains with tilting by inertial forces:

Trains with active tilting with sensory information given by accelerometers:

Trains with tilting controlled by a computer:

Trains with active suspension:

[edit] See also

[edit] References

  1. ^ http://www.memagazine.org/backissues/membersonly/june98/features/tilting/tilting.html
  2. ^ Das Geheimnis der Achse. In: Süddeutsche Zeitung, 22. November 2008
  3. ^ Weisung für Triebfahrzeugführer der ICE-T vom 23. Oktober 2008
  4. ^ Neigung zum Riss.. In: Süddeutsche Zeitung online, 26. Oktober 2008

[edit] External links

Retrieved from "http://en.wikipedia.org/wiki/Tilting_train"
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