Contrôle de vitesse par balises

This article is about the French railway safety system KVB. For other uses, see KVB (disambiguation).

KVB or Contrôle de Vitesse par Balises^[1] ('Speed control by beacons') is a train protection system used on the French railways and in London St Pancras station. It checks and controls the speed of moving trains.^[2]

KVB consists of:

• The on-board installation, known as bord (aboard), which comprises:
  • an onboard computer (UEVAL) containing a processor, a communication unit and recording equipment
  • A visual interface for the use of the driver, which
    • permits data entry regarding the train's tonnage, length, category, etc.
    • displays information about speed-limit and stop signals. Note that only warnings to stop and information about temporary speed limits are displayed. It does not replicate trackside signals for the driver. This is because the KVB is a relayer of information and does not constitute the entire signal system in force on high speed lines.
  • An antenna, placed under the locomotive, to receive information sent by the ground installations.
• The ground-based or sol (ground) installations, made up of:
  • Beacons or balises - digital or analog transponders placed between the two track rails. These can be fixed beacons (sending a single set piece of information, e.g. placed at a point where there is a change of speed limit) or variable beacons (sending a variety of messages, so that one signal can send different sets of information as required).
  • A code box ensuring that the interface between the existing signal and the beacons can be switched.

The on-board computer generates two speed-thresholds based on the received signals from the balises. If the train is over the speed limit, passing the first speed-threshold, an audible alarm sounds and the control panel indicates to the driver to adjust the train speed without delay. If the second speed threshold is passed, the KVB automatically engages emergency brakes on the train.

The system is an adaptation of a similar Swedish system, which uses an Intel 8085 microprocessor. The first generation French KVB also used that technology.

The next revisions evolved towards a Motorola 68020 processor and the software was re-written using the B-Method.

The decision to implement this technology was made at the beginning of the 1990s following accidents such as the Flaujac crash in 1985^[3] and the 1991 Melun rail crash.^[4]

Every locomotive unit on the French national railway network, except those that operate connected to other locomotives, must be equipped with this system. More than 5,000 engines, including foreign locomotives that travel within France, are equipped. The TGV is equipped with this system for all of its routes over conventional rail lines.

A European system for train control, called ETCS, will replace this and many other diverse systems in the various member states of the European Union.

References

1. ^ "Contrôle" is abbreviated to "K", to distinguish it from "Commande"
2. ^ "Article describing KVB in French". http://www.carreweb.fr/dsp/kvbrsc.html. Retrieved 2008-06-08. 
3. ^ "Report of Flaujac train crash in NY times". The New York Times. 1985-08-05. http://query.nytimes.com/gst/fullpage.html?res=9F01E5D61038F936A3575BC0A963948260&sec=&spon=. Retrieved 2008-06-08. 
4. ^ "1991 Melun rail crash record". http://en.wikipedia.org/wiki/List_of_1950-1999_rail_accidents#1991. Retrieved 2008-06-08. 

External links

Page about the KVB and the Crocodile (in French)

This article incorporates information from this version of the equivalent article on the French Wikipedia.