The GB rail industry has employed high integrity software (HIS) for many years, primarily within signalling systems. There is now an increasing complexity to such systems, and also a more widespread application within rolling stock and electrification systems. It has been recognised that there is a weakness in the current capability of the rail industry as buyers to effectively specify, procure, and manage the lifecycle of such software compared to traditional electro-mechanical systems. This weakness has been brought into sharp focus by a small number of operational incidents in recent years which were caused by software or data preparation errors.
On behalf of the High Integrity Software Group (HISG), a subgroup of the System Safety Review Group (SSRG), this research aimed to define and share good practice in the area of software for high integrity railway applications. It provided the core material to support the preparation of guidance on being an informed client of software-based systems, including considerations of their specification, procurement and whole-life management. The research has drawn on good practice within the rail and other sectors, both in GB and internationally, and identified where to find relevant standards and other guidance.
To aid industry implementation, the findings are published in SPARK making them immediately available to users. To take this forward, the HISG and RSSB will work with cross-industry members to review the findings of this research to establish how this knowledge can be used to form the basis of a Railway Group Standard Guidance Note.
The finished guidance will benefit the infrastructure manager, train operators, and the rolling stock companies, as they will be able to precisely specify what is required from the software including lifetime management. Also, train builders and software suppliers will be in a better position to deliver what is required. This is expected to lead to optimised development and testing time for software, which should reduce its purchase cost and delivery lead time.