Railway

Definitions, terms, categories, characteristics

A railway is a track for the railway Convoi S , consisted of one or more files of Rail S whose spacing is maintained by a fixing on Traverse S, resting on ballast.
Une way in dead end ends in a Heurtoir (generally improperly called ridge-plow). According to the countries and the ways, they are public or private. Their management can be sub-contracted or assured in control. Special ways are devoted to the trains at high speed (TGV) .

The changes of ways are generally done by needles (or shuntings ): a train does not choose its direction, with rare exceptions. The bridge-turnings are used for the garage of the engines in Rotonde S.

Categories of ways

The ways are classified in several main categories, each one implying a maximum speed and a load with the axle. One distinguishes as follows:
  • the main roads, assigned to the circulation of the trains,
  • the lanes assigned to service road interns great railway complexes;
  • the shunt tracks, assigned to the operations, which can be old displaced main roads,
  • the sidings are shunt tracks assigned to the parking of rolling stock.
The distinction between the garage and shunt tracks is not always obvious. These ways can belong to more total networks including the Ferroutage, within the framework of the Intermodalité of transport.

Characteristics of a way

The principal parameters which characterize a railway are:
  • the type of rail used (weight, length, section),
  • mode of Fixing of the rails to the cross-pieces,
  • the length of the rails in way (normal bars fished or long welded rails)
  • the spacing of the rails, and allowed tolerances,
  • the type and density of the cross-pieces (travelage),
  • the layout longitudinally (radii of curvature and cant),
  • the vertical alignment (slope or slope),
  • the support (ballast or concrete),
  • the carrying capacity per linear meter or with the axle,
  • the speed of the trains (ways at high speed).

Spacing of the rails

There exist several standards of spacing of the rails: See the article spacing of the rails for more information.

Characteristics of a line

A railway line can be made up of only one way: one speaks in this case about “single track” or often about two ways: line with double track, more rarely three ways or more.

Other parameters which characterize a railway line, in addition to the type of way:

If it is an electrified line, the characteristics suitable for the electric feeding system:

  • standard of Catenary,
  • height of the overhead line,
  • standard of current (continuous, alternate, tension, frequency).

These characteristics will determine in particular the speed limit authorized on the line and the towing total weight, function also of the characteristics of rolling stock. In France for example, there mainly exist two types of currents: 1500 V continuous and 25 Kv alternate (on the LGV).

All these parameters must be taken into account to ensure the Interopérabilité railway networks.

It is necessary to note, concerning the French rail network, of the notable differences with the close networks, in addition to the diversity of the systems of indication:

  • with the Iberian peninsula, difference in spacing of the rails,
  • with the Great Britain, difference of gauge,
  • with the Germany, difference of current of traction (15000 V 16 2/3 Hz in Germany, 25000 V 50 Hz or continuous 1500 V in France)
  • with the Belgium, difference of current of traction (3000 V = in Belgium and 25000 V ~ 50Hz on the LGV and some lines.)

the private railways connecting of the factories or industrial sites (mining, coal-chemical industry, petrochemistry, etc) was sometimes called riding.

Maintenance

The manager of the way must take care has to ensure in all circumstance the safety and the regularity of circulations like, for the lines circulated by passenger trains, comfort.

With this intention, it must make sure that the state of wear of the various components of the way remains in an acceptable fork compared to the auquelles requests they are subjected.

When a specific failure of the one of the components (for example a rupture of rail) occurs, this one is replaced punctually. On the other hand, when the general state of one of the components is not satisfactory any more and is likely to involve a number of specific repairs too important, the whole of the components of this type will be replaced entirely (for example, general wear of the cross-pieces whereas the rails are always good, or conversely).

If all of the components of the way are noted at the end of the lifetime, then the worn way will be replaced by a new way. With the SNCF, such an operation of replacement, door, is called RVB (Renewal Sees and Ballast).

The geometrical state of the way affects great the comfort felt by the passengers, but also, in certain cases, with respect to safety. It must thus also be to him maintained in an acceptable fouchette according to the type of trains circulating on the way (presence or not of passenger trains) and the speed of the fastest trains on the section concerned.

The regular monitoring and maintenance must also relate to the whole of the works of art and the ground works (fill or distinct) being used for the establishment of the line.

When these operations of maintenance cannot be concluded, a provisional solution is to lower the speed authorized on the section in bad condition in order to continue to guarantee safety.

If the absence of maintenance had suddenly persisted, the only solution, extreme, guaranteeing safety are to close the line with any traffic, such as for example with the beginning of the year 2007 on the Ligne of the Causses connecting Béziers to Neussargues in the center of France.

The manager of the way must in addition also take care that the vegetation does not damage the way nor the equipment which is dependant for him (installations of indication or electric traction for example), that the dead sheets do not accumulate on the rails (because they make obstacle with a good adherence of the wheel on the rail, harming acceleration as with braking and involving, inter alia, of the problems of regularity).

Not to pollute the ground water (around the zones of Vittel or Evian in France for example, exploited for their water), the ways can be thermically weeded, instead of épandre of the pesticides Weeding S.

A management adapted and more respectful of the environment would make it possible to confer on the accesses of the railway a more important role of biological Corridor. It is along the ways that animals such as Hérisson S or squirrel can still enter downtown. The ways which cross channels or highways are sometimes borrowed (of night in general) by large mammals such as Sanglier S or Chevreuil S.

Environment

The rail is recognized like one of the means of the most interesting transports as regards Sustainable development and of safety.

But construction, operation, the maintenance and the end-of-life of the railways pose problems Environnement with, even if they are recognized quite less than those posed by the Route S and Autoroute S. For example:

  • noise and the vibrations
  • chemical weed control of the ways
  • the management of polluted sites in the past by the Creosote, of the Weeding S, the Hydrocarbon S, or the After-effects of war.
  • a contribution to the ecological Fragmentation of the ecosystems and populations animal and thus vegetable (because number of vegetable Propagule S must be transported, even partially digested by animals to ensure dispersion, the mixture and the evolution of the individuals and Gène S within the species and in the territory).

Case of the LGV

This contribution to fragmentation ecological, minor with the traditional trains (and quite less than for the roads), is major for TGV:
  • if their double fence protects the trains from the collisions with the large mammals, they constitute also a barrier tight with the circulation of many animals.
  • the Microclimate which is established on the ballast not vegetalized (not of evapotranspiration), and very draining is also opposed to their crossing per many species.
  • the effect of blast and brutal Overpressure/depression with the passage of the trains to more than 200 km/h can shock or wound mortally many species, to 1 meter or even more distance from the way.

The compensatory conservative measures and being expensive, they often were not envisaged or were installation on the first ways at high speed. And they remain very rare on the recent ways, which in addition, as the road ways can induce Remembrement S with the consequences even more negative on the Environnement.

Possible measurements

For strongly reducing fragmentation by ways TGV, one would need “transparent” ways much more for circulation of the flora and fauna (écoduc S more and broader, and correctly positioned, with more passages in viaduct and tunnels).

And when the opportunity arises new écoducs of it should be built where the ecologists will consider it relevant on the current ways (cf note annexed to the Diagram of collective service “ Natural spaces and Ruraux ”/IFEN, following the Law of orientation and durable installation of the Territory, which envisages this type of solutions in the areas particularly fragmented by the transport infrastructures).

See too

External bonds

  • detailed Diagram of a railway

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