Thirty years ago to the day - Nov 7, 1987 - Singapore's MRT system started operations, making the Republic the first South-east Asian country to have a metro. But the mood in Parliament yesterday was far from celebratory, dampened as it were by an unprecedented tunnel flooding at Bishan station which crippled a large part of the North-South Line on Oct 7 and 8.

A good half of the sitting was devoted to soul-searching on why SMRT - Singapore's dominant rail operator - has not been getting things right in recent years.

On top of answering piercing questions ranging from worker morale to human resource management to SMRT's now infamous "deep-seated cultural issues", Transport Minister Khaw Boon Wan delivered a 39-paragraph ministerial statement which focused on what caused the tunnel flooding and what actions have been taken since.

Mr Khaw said there was no need for a formal public inquiry, as the cause of the flooding - which he described repeatedly as "sad" and "embarrassing" - was clearly attributable to maintenance lapses on the part of SMRT.

It was not because of any inadequacy in the design of flood protection measures, he said.

Yet, he revealed that the sump pit pumps at Bishan station have now been upgraded to models which can handle silt and sludge better. And as importantly, the pumps will now be controlled by parallel float switches for better system redundancy. This was to overcome the current weakness in the system, where a switch to protect the pumps from operating at low water levels overrode the other float switches.

Even though each of the three pumps had its own float switch, this fourth switch detects low water levels to prevent the pumps from overheating when there is little or no water in the reservoir.

This override switch was the one found to have failed on Oct 7, preventing the others from activating the pumps.

The system would have been more robust if the fourth "stop" switch had been removed, and each individual pump had its own low-water cut-off. Many modern pumps have this in-built feature.

Why the override switch failed is still a mystery. In fact, Mr Khaw said all the pumps and float switches at Bishan were also found to be in working order after the incident. He said it will take the Land Transport Authority a few more weeks to finish its investigations.

Nevertheless, putting in place a more resilient system is clearly the right thing to do. Such a system, of course, does not absolve an operator from maintenance responsibilities. But it will be more forgiving to lapses than the previous design.

Other mysteries remain. For instance, SMRT said on Monday that even though the maintenance log may have been falsified between December 2016 and June 2017, the pump system was in fact last serviced on July 13 this year.

If true, this would have put the system well within the prescribed quarterly maintenance regimen.

Yet, the system failed on Oct 7, less than three months later.

Another puzzle is why the maintenance team wilfully falsified the maintenance log - not once, but on three consecutive occasions - and how it was able to get away with it.

This shocking revelation - made public by SMRT last week - came just a year after a whole series of standard operating procedure breaches led to two trainee technicians being mowed down by a train near Pasir Ris station.

These puzzles will no doubt be solved as investigations by the LTA and SMRT unfold.

Mr Khaw, meanwhile, said there was no need for a committee of inquiry (COI). Just as well, seeing how lapses continued to surface even after the last inquiry in 2012.

Instead, steps have been taken to review and audit SMRT's work processes. A team of experts from Taipei Metro will conduct "a thorough and independent review" of SMRT's operations. The bonuses of senior supervisors will be tied to the performance of their teams.

LTA and SMRT will form a Joint Readiness Inspection team to supplement SMRT's own internal audit system, which will be headed by ST Kinetics' chief technology officer Richard Kwok. These steps would probably be what a COI would recommend, anyway.

But Nee Soon GRC MP Lee Bee Wah pointed out that if workers lacked pride in what they did, no amount of audit can prevent lapses.

Mr Khaw concurred, adding that it is thus important for SMRT to "create the right organisational culture of professionalism, excellence and discipline". As recent events have demonstrated, that is far easier said than done.