SINGAPORE - While estimated lifespans of rail assets provide a guide on when they need to be replaced, they typically deteriorate at different rates and are changed out on an ad-hoc basis said Transport Minister Lui Tuck Yew.
Using the example of timber sleepers, Mr Lui told Parliament on Tuesday said while two different sets were used, the one which was installed later actually wore out more quickly than the older one, due to factors such as the type of wood and how it was treated.
He was replying to Non-constituency MP Gerald Giam's questions on whether replacement of rail assets was done on a timely basis in the light of the breakdown of the North-South and East-West Lines during the peak hour on July 7.
Timber sleepers are used to hold train tracks in place.
Mr Giam said the website of rail operator SMRT website indicated that sleepers last between 15 and 25 years, which meant replacement works should have been completed by 2002 or 2012, given that the MRT started operations in 1987. Mr Giam pointed out that SMRT only started replacing the sleepers in November 2012.
In response, Mr Lui said "the important thing is actually to monitor them on a consistent level, replace them on an ad-hoc basis as and when necessary".
"But when it reaches what is considered a critical threshold, then you want to consider changing them out, replacing them en masse, and in this case, we are doing so with concrete sleepers," he added.
Upgrading of track components also need to be prioritised, he said. For example, the replacement of the third-rail, which supplies power to the trains, faced a "slight delay" and could only be completed by 2017.
This was because there was a need to "de-conflict" the ongoing works, such as the sleeper replacement and the upgrading of the signalling system.
Mr Giam in his third clarification, later asked if Mr Lui agree that "a lot of these replacement works should have actually been started earlier on, pre-2012, in order to be able to complete... before the end of life of the system?"
To which Mr Lui replied: "I think it's not always clear when the end of life is. There may be an estimate given but because of varying conditions that can always change.
"And in any case I suspect that perfect foresight is as rare as 20/20 hindsight is common."