TGV

A Réseau-class 2nd-generation TGV train at Marseille St-Charles station.

A TGV Atlantique on an enhanced ordinary track.

Duplex double-deck TGVs offer higher capacities (510 total, out of which 182 are in first class) on heavily frequented routes, such as Paris-Marseille.

Duplexes have four rows of seats (two at the bottom, two at the top); the upper and lower levels are linked by staircases. Carriages communicate at the upper level. A wheelchair-accessible compartment is provided.

The original TGV livery was orange, since superseded by blue.

The TGV is France's train à grande vitesse; literally "high-speed train". Developed by Alstom and SNCF, and operated by SNCF, the French national railway company, it connects cities in France, especially Paris, and in some other neighbouring countries, such as Belgium and Switzerland. TGVs or trains derived from TGV design also operate in the Netherlands, Germany, South Korea, Spain, the United Kingdom, and the United States. TGV trains are manufactured primarily by Alstom, now often with the involvement of Bombardier.

The TGV is a passenger train, except for a small series of TGVs used for postal freight between Paris and Lyon, France.

History

The idea of the TGV was first proposed in the 1960s. The first prototype, known as TGV 001, was powered by gas turbines and generated its own electricity from oil, but after the 1973 energy crisis and the consequent sharp rise in the price of oil this was deemed impractical. The first fully electric prototype was completed in 1974, with the final version delivered in 1980 and the service opened to the public between Paris to Lyon on 27 September 1981.

Since then, dedicated lines to Tours/Le Mans, Calais, Brussels and Marseille have opened. A line to Strasbourg is under construction, as are dedicated high-speed lines to Cologne and Amsterdam. Further extensions into Spain and Italy are planned for the future. A high-speed line to London from Folkestone (see Channel Tunnel Rail Link) is also under construction, using SNCF engineering expertise.

The TGV is not the world's first commercial high-speed service, as the Japanese Shinkansen connected Tokyo and Osaka from 1 October 1964, nearly 17 years before the first TGVs entered commercial operation.

The TGV is one of the fastest commercially operating conventional trains in the world. Under test conditions, the TGV has reached speeds of 515.3 km/h (320.2 mph), setting a world record in 1990.

On the 28th November 2003 the TGV carried its billionth passenger since operations began in 1981. The two billion mark is expected to be reached in 2010.

Tracks

The TGV runs on dedicated tracks known as LGV (ligne à grande vitesse, "high-speed line"), allowing speeds of up to 320 km/h in normal operation on the newest lines. Originally defined as a line permitting speeds greater than 200 km/h, this has now been increased to 250 km/h. TGV trains can also run on conventional tracks (lignes classiques), albeit at the normal maximum line speed for those lines, up to a maximum of 220 km/h. This is an advantage that the TGV has over, for example, magnetic levitation trains, as it means that TGVs can serve far more destinations and can use city-centre stations (for example in Paris, Lyon, and Dijon). They now serve around 200 destinations in France and abroad.

The LGVs are similar to normal railway lines, but there are key differences:

• The radius of curves is higher so that trains can travel at higher speeds round them without increasing the centripetal force felt by passengers. This radius is usually greater than 4km, but new lines have minimum radii of 7km to allow for future increases in speed.
• If used only for high-speed traffic, lines can incorporate steeper gradients. This facilitates the planning of LGV routes and reduces the cost of construction. The momentum of TGV trains at high speed means that they can climb steep slopes without greatly increasing their energy consumption, and they can coast down. On the Paris-Sud-Est LGV there are gradients of 35‰ and on the German high-speed line between Cologne and Frankfurt they reach 40‰.
• Track alignment is more precise. Ballast is built into a stronger profile. There are more sleepers per km and all are made of concrete (either mono- or biblocs, the latter being when the sleeper consists of two separate blocks of concrete joined by a steel bar). Heavy rail (UIC 60) is used, and the rails themselves are more upright (1/40° as opposed to 1/20° on normal lines). Continuous welded rails in place of shorter, jointed rails means that the ride is comfortable at high speeds, without the usual 'clickety-clack' vibrations induced by rail joints.
• Track must be at least standard gauge (1.435 m) or wide gauge to allow speeds greater than 200 km/h. Japanese and Taiwanese LGV networks are therefore separated from the original narrow gauge network. On the Iberian peninsula, however, which uses wide gauge track on normal lines, standard gauge is used on LGVs so that they remain compatible with the rest of Europe.
• If tunnels are required, their diameter must be greater than that required by the gauge of the trains travelling through them, especially at the entrances. This is to limit the effects of air pressure changes.
• There is a minimum speed limit, that is to say trains which are not capable of high speed may not use LGVs, and their use is limited for the most part to passenger trains. Mixed traffic imposes severe restraints on the use of a high-speed line. Capacity reduces sharply if trains of differing speeds are on it. Freight trains and passenger trains passing also poses a risk due to the possible destabilisation of cargo caused by the air currents around the passing trains. Night use by slower traffic when TGVs are not running is also not possible. The line infrastructure is maintained at night so regular freight flows would not be viable. The steep gradients on TGV lines limit the weight of slow freight trains. Slower trains would also mean that the maximum track cant (banking on curves) would be limited, so for the same maximum speed LGVs would need to be built with curves of even higher radius. A mixed-traffic LGV would therefore be more expensive and difficult to plan to take account of the relief of land and obstacles. Mixed-traffic LGV lines are therefore limited only to a few certain stretches of less-used track, namely on the Tours branch of the LGV Atlantique, and on the planned Nimes/Montpellier branch of the LGV Mediterranée.
• LGVs are all electrified. Apart from the constraints involved in refuelling and carrying fuel on board trains, diesel traction cannot produce the continuous thrust required for high-speed running. Apart from the Italian high-speed line between Rome and Florence, which is currently electrified at 3 kV DC (the same as the rest of the Italian network, although conversion to the European standard for LGVs is planned), LGVs are electrified at high voltage AC: 15 kV 16.7 Hz in Germany and Austria, and 25 kV 50/60 Hz everywhere else, including future Italian high-speed lines.
• Catenary wires are kept at a higher tension than normal lines. This is because the pantograph causes oscillations in the wires, and the wave must travel faster than the train to avoid producing standing waves (high amplitude oscillations caused by the pantograph running under an already oscillating wire) which would cause the wires to break. This was a problem when attempting the rail speed record in 1990 when the tension had to be increased further still to accommodate train speeds of over 500 km/h.
• LGVs are fenced along their entire length to avoid animals on the line. Level crossings are not permitted and bridges over the tracks are equipped with sensors to detect if anything has fallen onto the line.

LGV Signalling

The TVM (or Transmission Voie-Machine) system is used for signalling on LGVs. Information is transmitted to trains via electrical pulses through the rails, giving indications (speed, target speed, stop/go) directly to the train driver through dashboard-mounted visual indicators rather than lineside signals - trains are travelling too fast to be sure of seeing lineside signal aspects. Trains are under the driver's control, though there are safeguards against driver errors that can safely bring the train to a stop.

The line is divided into signal blocks, the boundaries of which are marked by blue boards with a yellow triangle. The indicators on the dashboard show the maximum permitted speed for the block where the train is and also a target speed based on the profile of the line. The maximum permitted speed is based on factors such as the location of trains ahead (with steadily decreasing maximum permitted speeds in blocks closer to the rear of the next train), junctions, speed restrictions, the maximum speed of the train and an approaching end of LGV. As trains cannot usually stop in the distance of one signal block (which varies between a few hundred metres and a few kilometres), drivers are alerted when there is a requirement to slow down gradually several blocks in advance.

Two types of signalling are in use on the LGV: TVM-300, the older system and TVM-430. TVM-430 was first installed on the LGV Nord to the Channel Tunnel and Belgium, and supplies trains with more information that the older system, allowing the on-board system to generate a continuous speed control curve in the event of an emergency brake activation, and force and guide the driver to control the speed without releasing the brake. However, drivers can always anticipate braking as they know the maximum authorized speed in the block in front of them as well as in the block which they are in from the signalling system.

The signalling system is permissive, i.e. the driver of a train is permitted to proceed into an occupied block section without first obtaining authorization. Speed in this situation is limited to 30km/h (proceed with caution) and if the speed exceeds 35 km/h, the emergency brake is applied and the train stops. If the board marking the entrance to the block section is accompanied by a sign marked NF, the block section is not permissive, and the driver must obtain authorization from the OCC prior to entering.

Avignon TGV station.

TGV Stations

There has been a tendency to build new stations serving smaller locations in suburban areas or in the open countryside some miles away from the town, so as to be able to make a stop without incurring too great a time penalty. In some cases, such as the station serving Montceau-les-Mines and Le Creusot, the station was built in the middle between the two towns. Another example is the Haute Picardie station between Amiens and Saint-Quentin. This latter one was rather controversial, criticized in the press and by local government as too far from either town to be useful, and sited near a trunk road rather than a connecting railway line: it was often nicknamed la gare des betteraves, or 'beetroot station'.

A number of major new railway stations were built, some of which have been major architectural achievements in their own right. Avignon TGV station (left), opened in 2001, has won particular praise as one of the most remarkable stations on the network, with a spectacular 340m-long glazed roof that has led to the building being compared to a cathedral.

Rolling stock

A TGV train in Rennes, in Brittany.

TGV trains depart from Gare Montparnasse in Paris to western and south-western destinations.

File:Eurostar at Vauxhall.jpg

Long Eurostar trains connect London with Paris and Brussels through the Channel Tunnel.

TGV rolling stock differs from other types in that trains consist of semi-permanently coupled multiple units. Bogies are located between the carriages, supporting the carriages on either side, so that each carriage shares its bogies with the two adjacent to it. Locomotives at either end of the trains have their own bogies.

This design means that in the case of a derailment, the locomotive derails first and can move separately from the passenger carriages, which are more likely to stay upright and in line with the track. This is unlike normal trains which tend to split at the couplings and jacknife.

The disadvantage of the design is that it is difficult to split sets of carriages. The locomotives can be removed normally by uncoupling them, but to split the carriages requires the use of lifting equipment in maintenance depots which can lift an entire set at once. Once uncoupled, one of the carriage ends is left without a bogie at the split, so a bogie frame is required to hold it up.

SNCF operates a fleet of about 400 TGV trainsets. Six distinct types of TGV trains operate on French lines:

Type:	TGV Sud-Est
Years of Construction:	1978 - 1988
Sets built:	111 1/2 (103 bi-current for passenger use, 5 bi-current half-sets for La Poste (see below), 8 tri-current)
Entry into service:	1981
Composition:	2 power cars, 8 carriages (including 2 powered bogies)
Mass:	385 t
Length:	200 m
Width	2.81 m
Max. speed:	300 km/h (sets 1-102), 270 km/h (sets not upgraded)
Power:	6,450 kW
Capacity:	345 seats
Note:	A special version of this TGV, the TGV La Poste, without seats and painted yellow, is in service for the postal freight of La Poste.
Type:	TGV Atlantique
Years of Construction:	1988 - 1992
Sets built:	105 bi-current
Entry into service:	1989
Empty Mass:	444 t
Composition:	2 power cars, 10 carriages
Length:	237.5 m
Width	2.9 m
Max. speed:	300 km/h
Power:	8,800 kW
Capacity:	485 seats
Type:	TGV Réseau
Years of Construction:	1993 - 1996
Sets built:	79 (49 bi-current, 30 tri-current)
Entry into service:	1993
Empty Mass:	383 t
Composition:	2 power cars, 8 carriages
Length:	200 m
Width	2.81 m
Max. speed:	320 km/h
Power:	8,800 kW
Capacity:	377 seats
Type:	Eurostar/BR Class 373, known previously as TransManche Super Train (TMST)
Years of Construction:	1993 - 1994
Sets built:	76 half-sets, plus 1 spare power-car (66 tri-voltage, 10 quad-voltage). Ownership by SNCF: 16 full-sets, SNCB: 4 full-sets, Eurostar (UK): 18 full-sets (of which 7 for regional use, see below).
Entry into service:	1994
Mass:	752 t
Composition:	2 power cars, 18 carriages (including 2 powered bogies); 7 shorter trains (14 half-sets) consist of 2 power cards and 14 carriages, being built for UK Regional Eurostar use. Three of SNCF 18-car sets are used for French domestic use and painted in TGV colours. Five of 14-car sets are in a pool on lease to GNER for UK domestic use; 2 in "GNER" colours and 3 in white with Eurostar logos covered up or removed.
Length:	394 m
Max. speed:	300 km/h (the warning plates in the cab state 320km/h)
Power:	12,200 kW across 12 axles
Capacity:	766 (540+206) seats, 558 (444+114) seats on shorter Regional sets.
Type:	TGV Duplex
Years of Construction:	1996 - 1998, 2001 - 2002
Sets built:	42 (30 in first batch, 12 in second batch)
Entry into service:	1996
Mass:	386 t
Composition:	2 power cars, 8 carriages
Length:	200 m
Max. speed:	320 km/h
Power:	8,800 kW
Capacity:	512 seats
Type:	TGV POS
Entrance into service:	2006
Mass:	423 t
Composition:	2 power cars, 8 TGV Réseau carriages
Length:	200 m
Max. speed:	320 km/h
Power:	9,600 kW
Capacity:	375 seats

One complication is the multiple types of power supplies that the trains must accommodate. French TGVs must accommodate 1500 V DC (older lines, especially around Paris) as well as 25 kV AC (newer lines, including LGV). Trains crossing the border into Germany, Switzerland, Belgium, the Netherlands and the United Kingdom must accommodate foreign voltages. This has led to the construction of tri-current or even quadri-current TGVs. Eurostars have an additional complication, in that the trains collect their power from overhead lines for most of the way but have to rely on a third rail system during their journey through the London suburbs.

However, with completion of Section 2 of the Channel Tunnel Rail Link and a new train maintainance depot at Stratford in 2007, Eurostars will no longer use third rail lines to London Waterloo as part of normal operations. It is proposed to remove the then-disused "power collection shoes" from the power cars to reduce maintainance and the chances of the redundant external components contributing to accidents.

Network

France has around 1,200 km of LGV built over the past 20 years, with four new lines either proposed or under construction.

Existing lines

1. LGV Sud-Est (Paris Gare de Lyon to Lyon-Perrache), the first LGV (opened 1981)
2. LGV Atlantique (Paris Gare Montparnasse to Tours and Le Mans) (opened 1990)
3. LGV Nord Europe (Paris Gare du Nord to Lille and Brussels and on towards London, Amsterdam and Cologne) (opened 1993)
4. LGV Méditerranée (An extension of LGV Sud-Est: Lyon to Marseille Saint-Charles) (opened 2001)
5. LGV Interconnexion (LGV Sud-Est to LGV Nord Europe, east of Paris)

Planned lines

1. LGV Est (Paris Gare de l'Est-Strasbourg) (under construction, to open 2006)
2. LGV Rhin-Rhône (Strasbourg-Lyon)
3. Barcelona-Perpignan-Montpellier, which would connect the TGV to the Spanish AVE network
4. Lyon-Chambéry-Turin, which would extend the TGV into Italy
5. LGV Sud-Ouest Tours-Bordeaux and LGV Bretagne-Pays de la Loire Le Mans-Rennes, extending the LGV Atlantique
6. Bordeaux-Toulouse-Narbonne

Amsterdam and Cologne are already served by Thalys TGV trains running on ordinary track, though these connections are being upgraded to high-speed rail. London is presently served by Eurostar TGV trains running at high speeds via the partially-completed Channel Tunnel Rail Link and then at normal speeds along regular tracks through the London suburbs, although Eurostar will use a fully-segregated line once Section 2 of the link is complete.

TGV outside France

TGV technology has been adopted in a number of other countries:

• Thalys, connecting France to Belgium, Germany and the Netherlands
• Eurostar, connecting Great Britain to France and Belgium
• AVE, the high-speed network in Spain
• KTX, the high-speed network in South Korea
• Acela Express, a high-speed tilting train built by TGV participant Bombardier for the United States, which uses TGV motor technology (though the rest of the train is unrelated)

Impact

TGV lines have largely replaced air traffic between connected cities. Brussels–Paris in 90 minutes has increased commuting between the two capitals, and likewise the Paris–Marseille line has greatly reduced travel time. Towns such as Tours are becoming a part of "TGV commuter belt".

External links

• [1] English version of SNCF official TGV website
  • [2] SNCF website for British users
• [3] TGVweb
• [4] The history of the TGV
• TGV - The French High-speed Train Service at h2g2
• LGV2030: an unofficial website about TGV Network in 2030