Hybrid Train Detection allows to increase capacity, while at the same time reducing the necessary trackside train detection devices.

The Hybrid Train Detection (HTD) concept has been developed by the ERTMS Users Group with the active contributions of ProRail and Network Rail. The concept provides the following characteristics:

  1. It is fully compatible with the ETCS Baseline 4 specifications, i.e. it does not change these specifications.
  2. It combines train position reports (including train integrity status) provided by the ETCS onboard with limited implementation of track side train detection (TTD) to determine track occupancy.
  3. It increases the performance (short headways) by using the ETCS train position reports and train integrity information.
  4. It reduces costs due to a substantial reduction of TTD devices.
  5. It allows fast recovery from degraded situations (loss of communication between trackside and on-board, loss of train integrity) by making use of TTD instead of only relying on operational procedures.
  6. It offers an easy migration from pure TTD based implementations to HTD, as well as directly from Class B to HTD, because the fitment of train integrity function on-board is not an access criterion for acceptance of trains on a HTD line.
  7. It supports the use of fixed (virtual) blocks, which minimises the impact on operational procedures as used in pure TTD based implementations.

Based on the above-mentioned characteristics, the HTD concept provides a very attractive solution for the railway sector to increase the business case for the implementation of ERTMS/ETCS.
The HTD concept has been tested in the ENIF test facility, provided by Network Rail, in Hitchin UK in 2018. The tests have been successful. Some minor issues where detected, upon which the HTD specifications were corrected, but the concept appeared to meet the expectations in a real live implementation.

The current version offers the possibility to use information from individual axle counter points to improve performance.

The HTD concept (document 16E042) is publicly available and can be downloaded from this website.