In Japanese root cause analysis, if a Man – made mechanism fail, the true Root Cause is not a failure of technology BUT a Man Mistake ad the following will show.
Q1 – why did the NEASW rail.breakdow?
A1 – because the power tripped.
Q2 – why did the power trip?
A2 – because of electrical short circuit.
Q3 – why was there a short circuit?
A3a – because insulation had weakened.
A3b – because of water drip onto wires at third rail.
Q4a – why had insulation weakened?
A4a – SMRT Man Dud not have periodic checks and maintenance plans. ( stop at Man Mistake and do Mistake Proofing )
Q4b – why did water drop onto wires at third rail?
A4b – because man did not maintain roofing for no – leak. ( stop at Man Mistake and do Mistake-proofing).