Active ISA

What is the purpose of Independent Safety Assessment (ISA)?

For high levels of criticality, it is accepted good practice to obtain independent opinion on the quality of safety work. In some sectors this opinion is required by the regulator in the form of a contracted ISA, in other sectors acquiring second opinions is seen as a risk reduction exercise for system delivery. Whether the use of independent opinion is mandated or chosen, the independent opinion needs to deliver specific value. Altran Praxis has provided independent safety opinion in all of its sectors.

What is activeISA™?

activeISA™ is an approach to assessment developed by Praxis. The approach was created in response to a customer survey targeted at identifying innovation in ISA services. The survey identified that a truly value adding independent safety assessment should:

Provide a fresh view of the system risk – little benefit is obtained simply by repeating what has already been done, line-by-line reviewing of the original work, or of just checking process compliance.
Be proactive – the purpose of an Independent Safety Assessment is to assist the customer deliver a safe system on time and to budget, not to reactively review documents and add risk to a schedule.
Be tailored to the risk of the new system – assessment effort should be proportional to the risk the system introduces and use the most appropriate assessment technique.
Be justified – assessment opinion should be transparent, justified and open to critique. Where restrictions on the support from the independent assessment exist, they should be clearly justified and be limited in number to precisely the right set.

activeISA™ is a structured assessment method to deliver these requirements. activeISA™ contains a process and an underlying toolkit from which assessment techniques can be selected, dependent upon the safety risks of the system under assessment.

Why can Praxis be trusted as an independent safety assessor?

Praxis wrote Network Rail’s Yellow Book approach to Safety Management, a standard that is still actively used within the Rail industry. Praxis is also one of a small number of organisations accredited to train on the Yellow Book.
Praxis wrote the Application Note on ISA for the Yellow Book.
Praxis has been used as an independent safety assessor in all of its key markets, in the UK, Europe, the far East and Australia.
Praxis has carried out ISAs on military aircraft, control and instrumentation of new build nuclear reactors, railway re-signalling schemes and vehicles.
Praxis has been used to assess systems from tens of thousands of pounds to billions of pounds of value, as well as assessing blue-chip organisations and large multi-national development programmes.
Praxis staff include senior members of safety professional bodies, for example both current and past Chairmen of the Safety and Reliability Society are employed.

Case reference

Alstom's Tilt Authorisation and Speed Supervision (TASS) system

Challenge

A key supporting technology for Virgin Rail's high speed tilting trains is Alstom's Tilt Authorisation and Speed Supervision (TASS) system. On high-speed trains TASS authorises tilt where permitted, removes tilt authority in a safe manner where tilt is not permitted and supervises speed. Alstom wanted to procure an independent safety assessor to support the introduction of TASS onto the UK mainline railway including the Pendolino.

Engagement and approach

Praxis was the independent safety assessor for Alstom's Tilt Authorisation and Speed Supervision (TASS) system. The work included assessment of a range of safety (HAZ ID, HAZ Log, PHA, SHA, SILs, safety requirements, safety cases), quality, system design, hardware design and EMC/environmental qualification documents against the CENELEC standards and "Yellow Book 3". Praxis audited all aspects of safety and quality management, competency, system and hardware design processes and products, and played a key role in the assessment of the TASS trials and design safety cases. TASS is a benchmark application of Praxis' approach to assessment embodied in activeISA™.

Outcome

TASS was successfully introduced onto the UK mainline railway and Virgin's challenging timescales for passenger service were met. In addition Praxis was also awarded the Notified Body role for TASS and was able to offer Alstom cost-benefit across these dual elements of assurance.

Altran Group