Index number 50 /Up-to-Date


BlockSAT system’s electronics.

BlockSAT system’s electronics.

BlockSAT is an innovative system for the signaling and management of railroad traffic patented by SENER that allows safe traffic circulation without the need to install additional elements on the track.

SENER implements innovative technical solutions in all its projects to guarantee the safety of its operations. The latest development is BlockSAT, a new system to manage the railway operations based on GPS positioning and inertial navigation with wireless communications, especially designed for low-density traffic routes in which train detection systems are not in place.

Functioning of the system

BlockSAT is composed of on-board equipment which integrates a set of GPS receivers, Doppler radars and inertial sensors (gyroscopes) which allow the real-time computation of the train’s position and speed, as well as a determination of the occupied segments of track. A wireless communications system (GPRS/3G or satellite where coverage is poor) is responsible for transmitting this data to the control center, where another set of equipment is installed.

The BlockSAT unit at the control center is able to safely establish the possible routes for each train, using the track occupancy information, since the system calculates the incompatibilities. Once each route is created, the control center unit sends movement authorizations and restrictions to the trains. The on-board unit informs the train operator (who should acknowledge its reception) of the movement authorizations and speed restriction on the journey, whilst monitoring the train data at all times (position, track occupation and instantaneous speed) to inform the control center.

Thanks to constant monitoring of the position, speed and track occupation, the on-board unit verifies the completion of the movement authorizations received and ensures that no stop sign is overpassed and any maximum speed is exceeded, thanks to a HMI (Human-Machine Interface) device which generates alarms to alert the train operator. Furthermore, the on-board system is connected to the emergency stop brake, that can be activated if the operator does not succeed to accomplish the received instructions.

Therefore, BlockSAT is an automatic train protection system in which safety is not reliant on the human factor. It has been designed and constructed according to the European Union safety standards and it is a fail-safe system.

BlockSAT is an innovative system because it is the only one on the market that combines GPS signals, inertial navigation and wireless communications, to guarantee that routes are completely safe at all times, without the need for elements on the track to position the train.

Currently, SENER has completed the development of BlockSAT, which has been tested and is undergoing the validation process on freight routes in collaboration with Ferrocarrils de la Generalitat de Catalunya (FGC), which involves the installation of the system in three locomotives and in the FGC operational control center in Rubí (Barcelona).

Performance results during the first tests:

  • • Positioning of the train with an accuracy below 2 m, even in tunnels, where GPS signal is lost.
  • • Speed estimation accuracy below 0.5 m/s.
  • • Optimal detection of track occupancy on parallel tracks after passing a switch point.
  • • Continuous communication with the control center by GPRS link without data-loss.

Subsequent to the validation of BlockSAT in the FGCs freight routes, it shall be implemented as a signaling and operation system on the passenger line from Lérida to La Pobla de Segur, which will be able to be operated from the Rubí control center.

BlockSAT has joined forces with other cutting-edge technological solutions for transport infrastructure from SENER, such as the STElec software for railway traction power simulations, employed by Ferrocarril Metropolità de Barcelona (FMB) in its vehicles; a crosswind prediction system; and Aerotraviesa®, a sleeper design that minimizes flying ballast, which SENER played a key role in developing in collaboration with Adif, Universidad Politécnica de Madrid and the CIDAUT Foundation.


• Upgrades the use of low-density railway lines without large track investments.

• Automatic protection of the rolling stock, regardless of the human factor.

• Centralized control of the trains, with no geographical limitations.

• Flexibility in the management of rail operations.

• Increases in the infrastructure transportation capacity.

• Highest safety levels (CENELEC), reliability and redundancy: fail-safe.


Blocksat  equipment.  Blocksat system’s screenshot.

Copyright SENER 2020