When it boils down to safety versus reliability, SMRT had to prioritise safety first, said SMRT chief engineer Ng Chong Joo, according to The Straits Times.
At the Committee of Inquiry (COI) on Monday, Mr Ng repeatedly emphasised that rail operator SMRT Corp focuses on the condition of the running rail instead of the power-supplying 'third rail' during maintenance. This is because the running rail determines safety, and the third rail, reliability.
Collapsed sections of the the power-supplying third rail had caused the two major disruptions in December, affecting over 200,000 passengers.
Mr Ng was questioned by COI panelists and explained that SMRT manages their maintenance system according to priority.
According to The Straits Times, Professor Lim Mong King from the Nanyang Technological University's School of Mechanical and Aerospace Engineering asked: "Don't you think reliability is also important?"
'Yes, it's important,' replied Mr Ng. 'But in a system, there are so many components, so we manage the system according to priority.'
He added that while a problem with the third rail would cause a service disruption, a failed running rail would have 'catastrophic' results.