High-speed rail in France
As of June 2021, the French high-speed rail network comprises 2,800 km (1,740 mi) of tracks,[1] making it one of the largest in Europe and the world.
In addition to serving destinations across France, the high-speed rail system is also connected to the United Kingdom, Spain, Belgium, the Netherlands, Luxembourg, Germany, Switzerland, and Italy.
Besides its main operator, the SNCF, it is also used by Eurostar, Thalys, Deutsche Bahn, Trenitalia France, RENFE, and the Swiss Federal Railways.
Like most high-speed trains in Europe, TGVs also run on conventional tracks (French: lignes classiques), at the normal maximum speed for those lines, up to 220 km/h (137 mph).
This allows them to reach secondary destinations or city centres without building new tracks all the way, reducing costs compared to the magnetic levitation train project in Japan, for example, or complete high-speed networks with a different gauge from the surrounding conventional networks, in Spain and Japan, for example.
The radii of curves are larger so that trains can traverse them at higher speeds without increasing the centripetal acceleration felt by passengers.
The considerable momentum at high speeds also helps to climb these slopes very quickly without greatly increasing energy consumption.
Eliminating these gaps makes the passage of a TGV over LGV switches imperceptible to passengers, reduces stresses on wheels and track, and permits much higher speeds, 160 km/h (99 mph).
The permitted axle load on LGV lines is 17 t, imposed to prevent heavy rolling stock from prematurely damaging the very accurate track alignment ('surface') required for high-speed operation.
The British High Speed 1 from the Channel Tunnel to London has been built with passing loops to support freight use, but this facility is used infrequently.
Outside France, LGV-type lines often carry non-TGV intercity traffic, often as a requirement of the initial funding commitments.
The Channel Tunnel is not an LGV, but it uses LGV-type TVM signalling for mixed freight, shuttle and Eurostar traffic at between 100 and 160 km/h (60 and 100 mph).
The standard pathway for allocation purposes is the time taken by a Eurotunnel shuttle train (maximum speed 140 km/h (87 mph)) to traverse the tunnel.
On lignes classiques, slower maximum speeds prevent oscillation problems, and on DC lines both pantographs must be raised to draw sufficient current.
An LGV is divided into signal blocks of about 1500 m (≈1 mile) with the boundaries marked by blue boards with a yellow triangle.
Among other benefits, TVM-430 allows a train's onboard computer to generate a continuous speed control curve in the event of an emergency brake activation, effectively forcing the driver to reduce speed safely without releasing the brake by displaying the Flashing Signal Aspects on the speedometer.
The signalling system is normally permissive: the driver of a train is permitted to proceed into an occupied block section without first obtaining authorisation.
When trains enter or leave LGVs they pass over a ground loop that automatically switches the driver's dashboard indicators to the appropriate signalling system.
Since ERTMS is mandated for eventual adoption throughout the European Union,[5] similar installations including ETCS signalling are expected on future LGVs.
One of the main advantages of TGV over technologies such as magnetic levitation is that TGVs can use existing infrastructure at its lower design speed.
LGV route designers have tended to build new intermediate stations in suburban areas or in the open countryside several kilometers away from cities.
The press and local authorities criticised Haute Picardie as being too far from either town to be convenient, and too far from connecting railway lines to be useful for travellers.
As part of their service cooperation with SNCF Voyageurs between France and Germany (formerly named Alleo), Deutsche Bahn operates on the LGV Est since 2007.
In June 2021 there were approximately 2,800 km (1,740 mi) of Lignes à Grande Vitesse (LGV), with four additional line sections under construction.
Some cities are mostly served by TGVs through so called "beetroot stations" (named after Haute Picardie TGV which was surrounded by sugar beet fields at the time it opened) well outside the built up area but conveniently located along the existing LGV.
However, this results in less services between the towns apart from Paris, even if they are situated along the same LGV (e.g. Tours to Bordeaux or Lyon to Marseille), and thus also less suitable interconnections to and between secondary lines.
The vast majority of TGVs serving Paris stop at one of the old terminus stations dating back to the 19th century, before the formation of SNCF.
