Although the defective China-made trains, which are still under warranty, are progressively being sent back to their Chinese manufacturer for repair ("5 of 26 defective China-made trains now fixed, says LTA"; Thursday), it is imperative to pre-empt future problems.

After all, the same consortium is still delivering new trains to Singapore. When it was awarded the contracts in 2014 (91 four-car trains) and last year (12 six-car trains), was it able to assure us that there would be no more of such defects?

How will we ensure that the "localised impurity" that occurred during the manufacturing process will not happen again (" 'Impurities in material' caused cracks on MRT trains"; Thursday)?

In the current scenario, as the hairline cracks are not critical to safety or performance, doing the repair in batches of one to two trains gives a resultant total repair duration of five years - 2014 to 2019 - which, though unpleasant, is still bearable.

Going forward, 103 more trains from this same manufacturer are coming into our fold. Based on a similar defect rate, which is about 75 per cent based on the 35 trains delivered, we are looking at a much longer repair timeframe.

Is repairing them in Singapore an option? If so, the contractor could be made to have teams ready for deployment in Singapore to assist in that.

And as our current depots do not have the required space or facilities, do we intend to build one that has?

Tackling these hard questions will help us take a step towards better public transport reliability.

Seow Joo Heng