ALSN ( Continuous Automatic locomotive signaling - Автоматическая Локомотивная Сигнализация Непрерывного действия ) is a train control system, based on main routes in the countries of the former USSR, for example, is installed in Lithuania, Estonia, the Russian Federation, Belarus. On high- speed lines, the extended version of AS - EN is installed that works with dual carrier frequencies. The modern train control systems with KLUB- U cab signaling are also equipped with sensors for ALSN / ALS EN wayside equipment.


The term ALSN ( АЛСН - автоматическая локомотивная сигнализация непрерывного действия ) is composed of ALS literally " Automatic locomotive signaling " ( АЛС - автоматическая локомотивная сигнализация ) and the variant specified N for " Continuous effect " ( Н - Непрерывного действия ). Other variants of the same scheme are ALST ( АЛСТ ) for " Point-type Automatic locomotive signaling " ( автоматическая локомотивная сигнализация точечного действия ) and ALSR ( АЛСР ) for " Radio- Automatic locomotive signaling " ( автоматическая локомотивная сигнализация с использованием радиоканала ). The term AS -ARS ( АЛС - АРС ) refers to " Automatic locomotive signaling with automatic speed regulation" ( автоматическая локомотивная сигнализация с автоматическим регулированием скорости ) for systems in automated driving.


ALSN includes the cab signaling and automatic Zugbremseinrichtung. The system is supported on coded track circuits. These are built with conventional relay technology.

Data transfer to the train done with 50, 25 or 75 Hz carrier frequency and numerical coding. On the vehicle are four signaling concepts - 3 codes and code absence - transferred.

The driver are displayed:

  • Sound announcement in case the code is changed to a more restrictive code
  • Aspect of the on-board signal, corresponding to the received code

It monitors:

  • Confirmation of the absence of a code every 40-90 seconds
  • Confirming a restrictive by driver within 15 seconds
  • Continuous speed supervision after passing the STOP field-side signal

The emergency brake is triggered in the following cases:

  • Audible warning is not acknowledged by the driver
  • Passing the STOP field-side signal
  • Exceeding the predetermined actual signal speed value

ALSN will regard ETCS out as a Class B system.