What is BS EN 50668 – Signalling and control systems about?  
BS EN 50668 is a European standard that discusses railway applications. It outlines best practices for maintaining both performance and quality of signalling and control systems.
BS EN 50668 specifies minimum functional requirements for urban rail signalling and control systems:
- Which operate on line of sight or using automatic interlock signalling with intermittent train control
- Not covered by the existing UGTMS standard EN 62290 series
- Not forming a part of an urban traffic control system but possibly interfaced with such systems. 
Note: BS EN 50668 is not applicable to command-and-control systems for urban rail using continuous data transmission and continuous supervision of train movements by train protection profile (already covered by the EN 62290 series).
Who is BS EN 50668 - Signalling and control systems for? 
BS EN 50668 on signalling and control systems for non UGTMS Urban Rail systems is relevant to: 
- Manufacturers, designers and operators of railway
- Railway infrastructure
- Train operating companies (TOCs)
- Railway authorities
- Regulatory bodies
Why should you use BS EN 50668 - Signalling and control systems?  
Railway signalling systems facilitate the safe operation of the railway network, and their dependability and maintainability have a direct impact on the railway network's capacity and performance, in terms of both infrastructure and trains.
BS EN 50668 is restricted to minimum functional requirements which allow users to define more specific requirements based on the given framework of the system requirements at the top level. 
BS EN 50668 covers the following areas:
- Independent points
- Single-track track sections
- Level crossings
- Route control area
BS EN 50688 also provides hazard analysis for the aforementioned areas, that provide you with the specific mitigation measures and functions to be implemented.
BS EN 50668 ensures that the signalling system and their components are suitable for use on street alignment or off-street alignment. As a user, BS EN 50668 can assist you establish a smooth functioning rail system, and prevent unwanted occurrences such as collision with road traffic and derailment.
