How many people here are actually affected by train disruptions?
According to a survey by public transport app and mapping provider Moovit, more than half of commuters here were affected by at least one disruption in the past month.
Moovit, which claims it has around one million users here and 60 million users globally, conducted the online poll, which had 1,038 respondents.
Some 54.3 per cent said they experienced at least one disruption in the past month. Of these respondents, about a third said they had experienced one delay, another third said they experienced two, while the last third experienced three or more incidents.
If the poll is statistically representative, it would mean half of the estimated one million rail commuters faced a delay in the past month.
Most commuters affected (60.1 per cent) had their journeys delayed by up to 20 minutes, while the remainder experienced delays of more than 20 minutes, Moovit found.
DAILY V MONTH-LONG EXPERIENCE
On any given day, even with a major breakdown, the vast majority of commuters aren't affected. But because disruptions, especially minor ones, occur a few times a month, the cumulative chance that people experience them rises over a one-month recall period.
ECONOMIST WALTER THESEIRA, from the Singapore University of Social Sciences.
The poll was conducted between May 8 and 11. A similar poll Moovit conducted in Hong Kong found that 48 per cent of respondents experienced a disruption in the past month. Of this, 46 per cent encountered one incident, 33 per cent experienced two, and 21 per cent faced three or more.
National University of Singapore transport researcher Lee Der-Horng said the survey results were "not surprising".
Dr Lee said that if the rail network had one disruption per 200,000 train-km this year (it was 174,000 train-km last year), there would still be one delay every four days on the North-South Line and one per 3.6 days on the East-West Line.
He said the statistical projection is based on an average train frequency of one every four minutes.
"This means that even if we are able to achieve the 200,000 or 400,000 train-km target, train passengers will still experience breakdowns two or three times a month," he said, adding that having a network that is "breakdown-free is simply not possible".
Economist Walter Theseira from the Singapore University of Social Sciences said that if 98 per cent of daily trips are reliable, the monthly risk of encountering at least one unreliable trip is 33 per cent.
"On any given day, even with a major breakdown, the vast majority of commuters aren't affected," he said. "But because disruptions, especially minor ones, occur a few times a month, the cumulative chance that people experience them rises over a one-month recall period."
For example, he noted that if 97 per cent of daily trips are reliable, the corresponding monthly risk jumps to 46 per cent.
He added that the Moovit survey has a much longer recall period than the annual commuter satisfaction survey commissioned by the Land Transport Authority.
"Instead of asking about the last trip, it asks for the commuter's recollection over the last month," Dr Theseira noted.
In the month preceding the Moovit poll, there were at least half a dozen incidents on the rail network which resulted in delays of up to 25 minutes each.
Four were on the North-South Line, while the East-West, North-East and Downtown lines each had at least one.
Retiree Anthony Ng, 67, said he did not experience any rail delay in the past month. "So far so good," he said, but qualified his response by saying that he uses the trains only twice a week, and during off-peak hours.
Engineer Benjamin Yeo, 48, who switched from driving to taking public transport about a year ago, said he, too, has had an incident-free month.
However, Nanyang Technological University undergraduate Andrew Lim, 24, was among those affected by the Downtown Line disruption two weeks ago. It took him 40 minutes to travel from Bukit Panjang to Newton in the morning - twice as long as it usually takes.
Commenting on the survey findings, Government Parliamentary Committee for Transport chairman Sitoh Yih Pin said: "There is always room for improvement regardless of the statistics. It is clear that we are constantly striving to improve rail reliability... I hope that Singaporeans can be understanding and patient as the Government continues to work hard at improving rail reliability."