[UPDATE 18 August, 9am: Normal train service has resumed on NEL after overnight repairs, says SBS Transit]
Two faults on the North-East Line (NEL) on Friday affected thousands of commuters as repairs took almost the entire day.
Early on Friday morning, a power fault on the the S$4.6 billion dollar train line resulted in delays of up to 50 minutes for passengers on the line.
In a statement, SBS Transit, which operates NEL, said that a signalling fault that had been discovered later at 2:45pm has been fixed.
"Train frequencies, however, continue to be lower due to the traction power fault which will only be resolved at the end of revenue service today," the transport operator said.
Train frequency during the evening peak period is expected to be between 7.5 and 8 minutes, and journey times from Punggol to Harbourfront is expected to be in the range of 33 and 35 minutes, it added.
The cause of the initial delay in the morning was traced to a fault in the traction power system.
To restore the line to normalcy, the traction power system had to be shut down, said SBS Transit.
As that would mean there would be no train services on NEL between HarbourFront and Dhoby Ghaut "for a period of time", the transport operator said that management decided to undertake the repair works, which are expected to last about two hours, after the end of service on Friday.
SBS Transit explained that in the morning, a stainless steel U-shaped bolt holding the cantilever arm of the overhead power cables broke in the northbound tunnel between HarbourFront and Outram Park Stations. The bolt's breakage caused power wires to be misaligned.
To avoid the risk of damage to the trains and overhead power wires, a section of the tunnel was closed, which forced trains to only turn around at one point in the tunnel instead of two normally, SBS Transit said.
In its statement at 5:43pm, SBS Transit said that free bus shuttles are being activated and will run during the evening peak period from 5:30pm along the entire line.
In the morning, SBS Transit sent two separate SMS alerts to inform commuters of potential delays and apologising for the inconvenience caused.
The first at 708am said services between HarbourFront and Dhoby Ghaut station would be delayed by about 10-15 minutes due to a power fault.
The second at 740am merely said train service was due to a power fault and that additional journey time of about 15 minutes in both directions may be expected.
But even up till 930am, commuters were still reporting several delays lasting for more than a few minutes at each station.
At around 1050am, the announcement at train stations was updated to inform commuters of a 30-minute delay.
Frustrated commuters took to Twitter to ask NEL to update its breakdown alerts.
Twitter user @PrincessLayla tweeted, "NEL Darling, your 10-15 mins has stretched into half an hour".
Veteran blogger @mrbrown tweeted "Power Fault at NEL Punggol-Harbourfront is causing peak hour delays. Each stop takes 10 mins wait before train leaves".
A student who only wanted to be known as Lim was stranded at the HarbourFront station for over 20 minutes and said he was confused by the NEL updates.
He told Yahoo! Singapore, "I've been waiting here for the last 20 minutes and there has been no train. I spoke to the staff here and they said that the trains will take around 30 minutes between each station if I want to take the train."
Commuter Nicole Quek was also among those affected.
She said her journey from Punggol to Outram station took longer than 50 minutes, resulting in her being late for work by 20 minutes.
"Based on their announcement, I reported 15-20 minutes late for work, but it took the train longer than 50 mins from Punggol to Outram station.... I will appreciate if SBS Transit could verify their facts before making any announcement."
She added that what made matters worse was that at Chinatown station, an announcement said the train would terminate at the station, resulting in many passengers alighting the train. As it turned out, it was a wrong announcement and no one bothered to clarify.
At 3pm, an SBS Transit spokesperson said, "We apologise that the delay on NEL is now extended to 30 mins due to a new fault that has been found in our signalling system."
Earlier in March, 90,000 commuters were affected when the NEL line was hit by two separate delays lasting hours between the Dhoby Ghaut and Harbour Front stations due to snapped cable lines.