The Safety standards for Railway (CENELEC – EN 50128, EN 50129, EN 50126) have introduced unified requirements for building Safety related electronic systems, which consist of software and hardware. Before the establishment of the CENELEC standards, countries had local standards, which were not as stringent as the CENELEC standards. The standardization lead to a unified
understanding of Safety and quality, which is definitely positive, but it also forced companies to adopt a more costly development and certification process for Safety systems.
Both Safety standards EN 50128 (Software for Railway control and protection systems) and EN 50129 (Safety-related electronic systems for signalling), define generic (software) applications and generic (hardware) products, which can obtain an independent Safety approval. When building a complex Safety system, these generic products can be reused, including their existing certification artefacts. With this approach a Safety-related electronic system can be composed out of pre-certified software and hardware modules.