Automatic Block Signalling

Automatic block signalling (ABS) is a method of railway signalling whereby a railway line is divided into a succession of track sections or blocks. Axle counters are installed at the ends of these sections to enable continuous train detection along the rail line. These axle counters then control the stop signals, governing train entry into an automatic block section.  
ABS makes it possible for trains travelling in the same direction to safely follow each other without the risk of rear-end collisions. This makes the use of an ABS system very cost-effective and leads to an increase in capacity. 


  • Shunting movements 
  • Less time available for reset and restart at busy stations
  • Communication between stations depends on available media (dark/ fibre/ quad/ E1 channel).
  • Quick installation and removal during track maintenance work required
  • Failures of the electronics on the track caused by external influences (lightning, traction current, etc.)
  • Maintenance crews on the track can cause temporary influences that affect the axle counters.
  • Limited space between tracks for equipment, personnel, etc.
  • Conventional axle counters generally have very complex hardware that takes up a lot of space.
  • Drilling holes into the tracks is a time-consuming process when installing sensors in complex track layouts.


The Frauscher Advanced Counter FAdC system is flexible in its design/architecture and can be configured for ABS train detection.

  • At the beginning and at the end of each track section, a wheel sensor is installed which, together with other components, forms the counting head.
  • Wheel sensors are connected to axle counting equipment installed at the nearest station and auto location hut (ALH) if available.
  • The information can then be transmitted between stations and ALH locations via an ethernet network, and the track status can be output on one or all of them. 
  • Reset options are available with significantly reduced hardware. 


  • Modular and scalable structure 
  • The FAdC system is very flexible, as it can transmit the track status to any location within the network. 
  • Maintenance friendly and requires less personnel on the track
  • Virtual SIL4-compliant supervisor track section available without the need for additional hardware
  • Compact wheel sensors fit in tight spaces between rails in case of complex track layouts
  • No active trackside electronics: no need for earthing, power cables and additional protective housings.
  • All electronic adjustments are carried out indoors requiring less access to the tracks for such activities.
  • No drilling of holes into the rail required
  • Communication media can be connected either via quad, fibre, or both without requiring a media switchover 
  • Optimised hardware makes the system fail-safe and reliable 
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