Five major MRT service disruptions occurred in just the first quarter of this year, already close to half the total last year, The Straits Times has learnt.
According to figures on the Land Transport Authority (LTA) website, there were five service delays lasting more than 30 minutes between January and March this year.
This was almost half of the 12 such disruptions for the whole of last year; there were eight such delays each in 2012 and 2013.
Incidents this year included a breakdown that lasted four hours and 38 minutes on the North-South Line on Feb 23, between Yew Tee and Kranji stations.
When the number of major service delays in the first quarter of the year is averaged out over 100,000km of train distance travelled, the incident rate is around 0.07. This is up from 0.04 last year, and 0.03 in 2012 and 2013.
It is also higher than the 0.05 in 2011, which saw two major breakdowns on the North-South Line on Dec 15 and Dec 17.
Asked yesterday why the number of major disruptions is creeping up despite the lessons learnt from earlier disruptions in 2011, LTA chief executive Chew Men Leong noted that much has been done to boost MRT reliability since then.
"LTA and SMRT have followed up with the recommendations of the COI (committee of inquiry) to tighten up the maintenance regime," Mr Chew noted.
He said that joint working teams have been formed by the LTA and the public transport operators (PTOs), with the upgrading of key assets on the North-South and East-West lines - such as sleepers, signalling systems and the third-rail - also under way.
He said these efforts have "made useful improvements", but added: "Is it good enough? Is there room for improvement? I would say definitely so."
"We are intensifying overall audits of the PTOs' maintenance regimes, to see how adequate they are and where are the gaps," Mr Chew said at a press conference yesterday to discuss findings on the July 7 disruption which crippled both the North-South and East-West lines.
At the same event, SMRT chief executive Desmond Kuek said that it "takes time" to develop new condition monitoring systems, which are not available off-the-shelf.
Meanwhile, the total number of service delays of more than five minutes has been reduced across the MRT network over the years.
The incident rate per 100,000km in the first quarter of this year was 0.79, down from 1.17 last year.
It was also lower than in 2013 (1.18), 2012 (1.49) and 2011 (1.75).
Separately, four major service delays occurred on the LRT network in the first quarter, all on the Bukit Panjang LRT system. For the whole of last year, just five such service delays took place across the LRT network.