We refer to Mr Shawn Lee Chieh Long’s letter (“What’s LTA’s role in equipment maintenance?”) on 18 October, and Mr Chin Neep Hing’s letter (“Maintenance won’t help if design is flawed”) on 21 October.

Under the October 2016 New Rail Financing Framework (NRFF) arrangement, SMRT remains responsible for providing reliable and well-maintained rail services, which includes ensuring that rail operating assets are in good working condition, replacing faulty components and establishing a comprehensive maintenance regime.

Meanwhile, as owner of the rail operating assets, LTA carries out regular audits of the rail operators’ maintenance records and on-site inspections, and has flagged out maintenance lapses to SMRT for rectification. LTA also regularly meets with SMRT to assess their maintenance plans and has highlighted components due for replacement. To provide stronger oversight, LTA set up a dedicated “Rail Assets, Operations and Maintenance Group” last year to oversee condition assurance and stewardship of our rail operating assets.  However, primary responsibility ultimately remains with the rail operators who must ensure that the assets are in a condition befitting their age or else compensate LTA for them.

The MRT tunnel flooding on 7 October was caused by the multiple failure of redundancies and buffers built into the storm water pump system. First, the malfunction of the “stop” float switch prevented pumps in the storm water pit from activating to discharge water collected. Second, a separate and independent “alarm” float switch also failed to alert SMRT of high water levels accumulating in the storm water pit. Third, the storm water pit, which is sized to contain six hours of continuous rainfall, was already full and therefore unable to cater to the further rainwater on 7 October afternoon. It should have been empty if it had been properly maintained.

From a design perspective, it is very unlikely that both the “stop” and “alarm” float switches fail concurrently, which underscores the importance of regular maintenance and checks. The design of the float switches is also not unique to the Singapore rail system, and is widely utilised in many other submerged pump applications.

LTA has always been committed to working closely with all our rail operators to improve their maintenance processes.

Chua Chong Kheng 
Deputy Chief Executive (Infrastructure and Development) 
Land Transport Authority