How sustainable is safety?

SFAIRP (so far as is reasonably practicable) principle in rail industry often uses standards as baseline safety argument and looks what else can be done for safety benefit, over and above standards. Only where specific constraints prevent application of the standard, in such cases SFAIRP will apply to lowering the practice below standard, only to a balanced point. 

"SFAIRP principle does not challenge the standard but rather relies on it and works for safety benefit to improve the practice or guard its concessions". 

Sustainability is at the spectrum of asset performance, which typically competes with safety. Sustainability has not been deemed historically as a valid trigger to deviate from standards, which are perceived as holding an acceptable balance of performance vs safety. Swaying the balance of standard must come with the argument contributing to both domains - performance and safety. 

While showing relevance of sustainability to performance is obvious, it is harder to connect it with safety. If sustainability could demonstrate a safety benefit with monetary equivalent, then a cost benefit analysis could demonstrate SFAIRP. Otherwise, it stays to be an ages old dilemma of performance vs safety. Practice and practitioners, governance and governors - all find blame game not helping. 

Where sustainability increases reliability of safety controls or reduces cumulative risk for maintenance - such initiative has demonstrable quantitative safety benefits, e.g., light bulbs to LED replacement in switchboards or station lighting. But where sustainability degrades core safety controls without providing equivalent safety benefit - it shall be rejected, e.g., using less concrete or steel to reduce safety factor from x2 to x1.8.

In addition, sustainability could be interpreted as a competency continuity within organisation, where human recourses policy ensures cross generational transfer of skills via mentorship programs and strategic grouping of work force on projects.