Singapore’s rail system has once again come under scrutiny, as Joleen Teo, a mathematical and theoretical physicist by training, publicly challenged the Ministry of Transport’s claims of strong reliability.
Her intervention came after Acting Transport Minister Jeffrey Siow defended Singapore’s rail system as among the most reliable in the world.
In a TikTok video published on 25 September, Teo questioned the use of mean kilometres between failure (MKBF) as the primary metric of reliability.
She argued that mathematics should not be used as an excuse to normalise train breakdowns.
Based on her own estimates, Teo suggested that rail reliability is “on track for a 20 per cent drop” from 2024 to 2025, which she said should not be considered an achievement.
Teo went further, estimated that train delays had already cost commuters 2 million lost hours worth S$47 million by July 2025, potentially rising to 4 million hours and S$81 million by year’s end.
“Let’s maybe not normalise train delays, and start doing our jobs,” she urged.
As of 3 October, Teo’s video has garnered over 167,000 views and nearly 10,000 likes.
Jeffrey Siow said zero train disruptions unrealistic but pledges stronger commuter support
Just days before Teo’s remarks, Acting Transport Minister Jeffrey Siow addressed Parliament on 22 September in response to multiple questions from Members of Parliament regarding a series of train disruptions over the past two months.
While acknowledging mounting public frustration, Siow cautioned that “zero disruptions” is an unrealistic expectation.
He stressed that the government’s goal remains to “absolutely minimise” disruptions, given the inconvenience faced by commuters.
“What is equally important is when a disruption inevitably happens, we can support commuters, and guide them to continuing their journeys safely, with their understanding and cooperation,” he said.
SMRT had earlier assured the public that the incidents were isolated and not systemic.
Figures released by the Land Transport Authority (LTA) on 5 September revealed that overall MRT reliability, measured by MKBF, had fallen to its lowest level in five years.
Source: LTA
Siow told Parliament that Singapore’s MKBF stood at 1.7 million train-kilometres in the 12 months to August 2025.
While this remained above the 1 million benchmark set in 2017, it was a marked decline from the 2022–2023 peak of over 2 million.
He added that Singapore’s figures were higher than Hong Kong’s MTR but lower than Taipei’s metro, while performance on long service delays was comparable to Tokyo’s metro networks.
He said he had asked LTA to publish such international comparisons regularly, acknowledging that Singaporeans often measure their MRT’s reliability against these systems.
MKBF and its limits
Members of Parliament pressed the government on whether MKBF targets should be raised or if yearly improvement goals should be introduced.
Siow replied that beyond 1 million train-kilometres, the metric becomes less meaningful because small variations can drastically change the figures when incidents are rare.
He pointed to the Downtown Line’s MKBF, which was 8 million in 2023 and 2024 but fell to 4 million this year following a single additional disruption.
Importantly, Siow acknowledged that MKBF does not measure the severity of incidents.
A complete service stoppage is treated the same as more frequent but shorter disruptions, even if trains remain moving and passengers are able to continue their journeys.
He added that LTA also considers commuter impact and imposes penalties on operators for serious disruptions.
PAP MP Tin Pei Ling had asked if MKBF remained a fair measure of performance as the network expanded.
Siow argued that reliability should be assessed relative to network size, saying: “As the rail network doubles, reliability would still be considered improved if the number of disruptions does not double.”
He emphasised that while MKBF had its limits, it remained useful for benchmarking and tracking long-term trends.
Teo highlights blind spots in government data
In her video, Teo strongly criticised MKBF as inadequate.
She highlighted that the metric counts any delay over five minutes as a “fault”, which she argued trivialises real disruptions.
Her analysis pointed out that in 2025, most significant delays lasted an hour or longer.
She estimated that 89 per cent of long delays occurred on lines operated by SMRT.
Teo also noted that MKBF treated incidents unevenly, citing the infamous six-day East–West Line breakdown in 2024, which cost SMRT more than S$10 million.
The incident, she said, was measured the same way as a six-minute disruption under MKBF.
She raised questions about the omission of the Thomson–East Coast Line (TEL) from the LTA’s 5 September report.
According to her hypothesis, TEL suffered three major breakdowns within four months, and its inclusion would have lowered reliability figures even further.
Declining performance across lines
Teo further illustrated her point with line-by-line comparisons. She estimated that the North–South Line had seen reliability fall by nearly half, while the Downtown Line also registered a drop of around 50 per cent.
The North East Line and Circle Line showed only marginal improvements.
Her calculations, based on publicly available and crowdsourced data, suggested a decline in reliability across the system, which she projected as a 20 per cent overall drop from 2024 to 2025.
“Even if you treat my calculations right now as ballpark figures, having the order of millions of hours lost to train delays is simply unacceptable,” she said.
Lost commuter hours and economic cost
Teo broke down her estimates into commuter hours and economic cost.
Based on available data up to July 2025, she calculated that around 2 million commuter hours had already been lost this year.
Extrapolating for the full year, she projected 4 million hours.
She then calculated the economic cost by multiplying these lost hours against Singapore’s median hourly wage, reaching S$47 million already, and as much as S$81 million by year-end.
“And this is just for the lost work,” she added.
“It’s not even including the cost of actually servicing and getting the trains back up and running, like the S$10 million spent on the East–West Line breakdown.”
Teo said the financial implications were compounded by operators receiving government subsidies while reporting profits, even as commuters endured more disruptions.
She criticised the fare hike of 18.9 per cent, contrasting it with SMRT’s reported profits of S$6.2 million.
“We get more delays, they earn more money — good deal, right?” she remarked.
Public engagement and transparency
Teo concluded her video by calling for greater transparency in rail reliability reporting.
She argued that Singapore’s ability to improve its rail system depended on accurately assessing performance, which required more comprehensive data.
She announced plans to release her calculations, data plots, and visualisations on a public Github account, inviting others to review and improve upon her estimates.
“At the end of the day, improving our rail system involves being able to accurately self-assess our performance — and we cannot do that when you’re just using mathematics as an excuse.”
@suchabohr mathematical breakdown of MRT breakdowns. these numbers gonna make me break down crying fr #tiktoksg #fyp #sg #singapore ♬ original sound – jo teo
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