Computer based interlockings: Pioneers of a new railway control system

While solid state interlockings (SSI) control turnouts and signals via classic electrical circuits and often kilometre-long cable connections, CBI technology is based on a fully digital communication architecture. Control commands are transmitted via IP-based fibre optic cables to field elements such as switches and signals. The technology enables complete modularisation, standardisation and decentralised control. Updates and adjustments to software and hardware can be carried out without extensive modifications.

Remote diagnosis, modularity, staff efficiency

The introduction of digital interlocking technology offers numerous technical and organisational advantages. Remote diagnosis allows operating conditions and fault patterns to be analysed and rectified in real time. Maintenance intervals are thus reduced and reliability is increased. The modular design of CBI allows existing systems to be modernised step by step and facilitates the integration of new components. The automated processes and centralised user interfaces help to reduce the number of staff required. At the same time, modern redundancy concepts ensure increased operational reliability and fault resistance, as failures of digital components can be quickly detected and compensated for.

Innovation and implementation

In Germany, the Annaberg-Buchholz CBI and the Emden-Oldenburg large-scale project are considered trendsetting pilot projects. The Annaberg-Buchholz digital interlocking began operation in 2018 as Europe's first digital interlocking and marks the starting point for the nationwide implementation of this generation of technology. It is exemplary for the digitalisation of control and signalling technology and serves as a reference for its gradual nationwide implementation to the German railway network.

The Emden-Oldenburg CBI is being implemented on an approximately 120-kilometre-long main line. It is considered the first project in the north-west to control a central artery in extensive real-world operation, which is of crucial importance for long-distance passenger transport as well as for the rapidly growing freight traffic to North Sea ports. Digitalisation will enable higher train frequencies, denser timetables and more reliable capacity utilisation. Siemens Mobility, Alstom, Thales and voestalpine SIGNALING are major contributors to its implementation, supplying components and control architectures for operation and implementation.

Skilled labour shortage and delivery times

It is not only a lack of skilled workers that is slowing down the implementation of digital interlockings. Lengthy planning and approval procedures as well as delays in the delivery of technological components are also extending the duration of projects.

Erzgebirge CBI – a digital showcase project

With its innovative cloud integration and digital field elements, the Erzgebirge (Ore Mountains) CBI in Annaberg-Buchholz, exemplifies the performance and flexibility of the CBI approach. In addition, a ‘real-world test laboratory’ for digital railway operations was created for the first time in the Erzgebirge, where new software and hardware solutions from manufacturers are tested, operational processes are simulated, training is provided and continuous optimisation takes place. The interlocking thus also serves as a training and further education location for skilled workers. Since it went into operation in 2018, operating costs have been reduced and the availability of the network has been sustainably increased. The Erzgebirge project is therefore considered to be more than a technical success; it is also an economic one. The location now serves as a reference for international railway companies for their own modernisation projects.