While I applaud the Land Transport Authority (LTA) and SMRT for having contingencies and for addressing the train breakdowns promptly, I question the professional opinions and competencies of the rail engineers with regard to the signalling tests (MRT delays may occur as tests continue; June 28).

As a trained engineer, I would not have tested a new system live without a predictable reliability of about 95 per cent. Imagine if a new system being tested in a nuclear plant failed; it would be disastrous.

Was the LTA and SMRT's team unable to predict the new signalling system's reliability before performing a live testing?

If they were able to, then I would say that the many breakdowns pertaining to signalling testing are a statistical phenomenon.

Perhaps the critical paths of failures have not been identified, due to the unfamiliarity of the system.

I hope the team can improve on its reliability predictions formula to ensure that the testing is just a formality to assure confidence, rather than a test of an uncertain system that creates inconvenience, frustration and disruption.

Edward Lee Chee Weng