Singapore's rail system continued to improve on the whole in the first quarter, even if the absolute number of major breakdowns remained high.

According to statistics released by the Land Transport Authority (LTA) yesterday, the MRT network had one disruption for every 159,000 train-km clocked - compared with one every 133,000 train-km at the end of last year.

Incidents are tallied if they delay journeys by more than five minutes.

As for the absolute number of longer disruptions - in particular those lasting more than 30 minutes - there were four on the MRT network in the first three months, and another four on the LRT network, bringing the total to eight.

For the whole of last year, there were 29 incidents for the entire rail network, which worked out to an average of 7.25 per quarter.

On this front, operator SBS Transit scored well, with no major disruption on its North-East and Downtown lines.

However, the North-East Line was the worst performer when shorter delays were included. The line chalked up one incident for every 93,000 train-km in the first quarter - up sharply from one in 213,000 train-km as of end-2015.

Its Downtown Line fared much better, chalking up one incident per 171,000 train-km - down from one in 45,000 train-km at the end of last year. This was largely because Stage 2 of the line opened in December, leading to longer distances clocked by brand-new trains, which are less likely to break down.

On the LRT front, the overall network clocked one incident for every 43,000 car-km travelled - down from one every 42,000 car- km at the end of last year. The LTA said it uses car-km as a measure for the LRT as the system uses a mix of one- and two-car trains.

National University of Singapore transport researcher Lee Der-Horng said the rail system is facing "new challenges" from its power systems, which have lately contributed increasingly to major breakdowns. "I do not know if there are even deeper root causes (of breakdowns) in our system which may prevent us from having a reliable MRT," he said.

Commuters interviewed, however, said they had noticed a slight improvement.

Finance analyst Kat Lee, 30, said she now encounters a minor glitch every two to three weeks on average - down from once a week.

Typical glitches, she said, would include trains stopping "in between stations for around five minutes".

Remisier Thomas Tay, 56, said he had noticed fewer incidents involving train doors that open and close several times before they are finally closed. "It still happens, but not as often," he said, adding that he was caught in only one major disruption in the first quarter.

In comparison, Hong Kong's MTR had three major glitches in the first quarter. Including minor glitches, it had one incident for every 520,000 train-km.