Railway signalling
Railway signalling systems are responsible for the safety of trains in terms of preventing collision or derailment.
The signalling system mainly consists of the traffic control system, the interlocking system and external trackside elements in the field:
- the traffic control system offers a human-machine interface which allows the control and operation of the signalling system
- the interlocking system is the main safety component of the signalling system, responsible for ensuring the safety of trains by generating and maintaining a safe path for the passage of a train
- the trackside elements provide the interaction betwen the infrastructure and the train by means of elements such as points, signals, balises and train detection.
This complex system is interlinked with a communications system and with a cabling system. Interfacing between the individual components is a major challenge.

Level crossing systems provide the safety on road-rail crossings, preventing access to the rails to road traffic during foreseen train movements.

Onboard systems on trains ensure that trains follow safely the allocated paths on the infrastructure.

The objectives in railway signalling are interoperability and open access to infrastructure. ERTMS/ETCS is a system that aims to achieve these objectives in Europe, and is on the way to become a global standard.

Railway telecommunications
Railway telecommunications must ensure reliable and quality communication service for the operation of rail traffic. The telecommunications infrastructure is an important part of the railway, as it conveys information required for the operation of trains.

The infrastructure must enable telecom and network services between train stations and working posts, transmission for signalling systems and traffic control, train radio or GSM-R, transmission for supporting scada systems,  passenger information and announcements, transmission of emergency calling systems and video transmission. The transmission related to the signalling systems must be executed safely, therefore safety layers are used in the communication protocols. In addition, security layers are needed when open network architecture is used.

Requirements engineering
Every project has requirements. That is valid for projects describing workflows and procedures or for projects developing software and hardware solutions. In order to make the project a success, the quality of the requirements is essential. The requirements must be complete, precise and unambiguous.

Requirements engineering is a process which relates to the entire development lifecycle and can be roughly apportioned into developing requirements, validating and verifying requirements and managing requirements.