LS (train protection)

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Driver's cab display LS II
Vehicle receiver LS II to a multiple unit of the series 451
Driver's cab display and control switch with the positions off , start and operation of the LS 90 train control system
LS 90 receiver on a class 471 multiple unit

LS is a train control system used on the railways in the Czech Republic ( SŽDC ) and Slovakia ( ŽSR ). The abbreviation LS stands for Czech Liniový Systém , which can be translated as continuous transmission .

LS is installed in the Czech Republic on all main lines with a permissible speed of over 100 km / h, in Slovakia on main lines with a speed of over 120 km / h. Most Czech and Slovak traction vehicles are equipped with an on-board unit that works with LS.

history

LS was developed based on the Soviet train control system ALSN and introduced at the beginning of the 1960s on the Czechoslovak State Railways ČSD . With LS, the goal was to achieve a smoother operational sequence, in that a changed signal setting can be transmitted to the locomotive at any time, regardless of the location of the train . This requirement required a system with continuous signal transmission . The system has been further developed step by step, with the versions LS II, LS III and LS IV using relay technology. Electronic circuits were used with the LS 90 at the beginning of the 1990s . At the same time, the first report on the uniform European train control system ETCS appeared , whereupon a further development of the Czechoslovak train control system was dispensed with. After the separation , however, only the Czech Republic saw itself bound by this decision. In Slovakia, Mirel has developed an on- board unit with an extended range of functions that works with LS's line equipment. The Czech LS 06 on-board unit has the same functions as the previous versions, but has been brought up to date through the use of microprocessors .

functionality

The trackside part of the system consists of coded track circuits that work with a carrier frequency . The data transmission between the coded track circuits and the on- board unit takes place via inductively coupled air coil antennas above the rails . Over routes with 3000 V direct current or with diesel locomotives to be operated, a carrier frequency is 50 Hz for use in alternating current lines and in railway stations , the carrier frequency is 75 Hz. These two carrier frequencies allow the transmission of four amplitude modulated signal information (including stop position). Depending on the signal position, one of four different square-wave frequencies is modulated onto the carrier frequency. As soon as a traction vehicle enters a track circuit equipped with LS, the transmission of the signal information begins, which the signal shows at the end of the block section . The vehicle antennas in front of the first axle receive the signal information. The driver's cab display consists of four lights to show the four pieces of signal information. Underneath there is another blue light that prompts you to operate the alertness button when it is switched off .

frequency Signal sign Display on
the vehicle		 speed
5.4 Hz free travel green maximum train speed
3.6 Hz Attention yellow 120 km / h
1.8 Hz 40 and be careful yellow ring 40 km / h
0.9 Hz Stop red 30 km / h
- without transmission - 120 km / h

When driving on sections without LS track equipment, the vigilance button must be operated regularly. On sections with LS track equipment, the vigilance button is only to be pressed when the signal signs caution and 40 and caution are transmitted . If this is not done, a horn will sound after one of the deadlines has elapsed and an emergency brake will be triggered after another 4 seconds . There is no braking distance monitoring. The vigilance control is not active at speeds below 15 km / h and the hand or parking brake applied .

Successor system standardized across Europe

In the foreseeable future, LS will be replaced by the standardized European train control system ETCS. In the Czech Republic there is a 22 km long test track equipped with ETCS Level 2 between Kolín and Poříčany . In Slovakia, the route from Bratislava - Rača to Nové Mesto nad Váhom is equipped with ETCS Level 1 .

With regard to ETCS, LS is listed as a Class B system (Class B system). A Specific Transmission Module (STM) is available for LS .

See also

literature