Contrôle de vitesse par balises
KVB or Contrôle de Vitesse par Balises (it could be translated by Speed control by beacons) is a train protection system used in France and in London St Pancras station. It checks and controls the speed of moving trains.
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.
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.
- (French) Page about the KVB and the Crocodile
- (PDF) Lines in France equipped with KVB, 2009
- (French) Avis du conseil général des ponts et chaussées, 2008
- (French) Bilan LOTI du KVB, 2008
- This article incorporates information from