Wednesday, 28 December 2016

MRT disruptions caused by signalling faults

Mystery of Circle Line's signalling problem solved

The mysterious signal interference which interrupted service on the Circle Line MRT in recent months is a mystery no more.

According to the Land Transport Authority (LTA) & train operator SMRT, investigations showed that signalling problems on the Circle Line were caused by an intermittent failure of the signalling hardware on one train.


Between Nov 2 & 6, the hardware failure on the train - No. 46 - had caused trains in the proximity of it to lose signalling communications.

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Delays on East-West Line due to track fault

A track fault caused delays for up to an hour on the East-West Line during morning rush hour on Wed (Jan 4).

The East-bound stretch from Boon Lay to Clementi stations was affected, train operator SMRT first said in a tweet at 7:47am.

It warned commuters to expect an additional 10 minutes travelling time, which it later revised to 15 minutes.

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SMRT's East-West Line suffers 3 faults in less than 24 hours

The East-West Line suffered three faults in less than 24 hrs, with the most recent one on Fri morning (Dec 23).

The 1st one happened on Thursday night. SMRT, posted on Twitter at about 7.30pm, an alert on the track fault, telling commuters to expect an additional 15 minutes of travel time from Outram Park station to Eunos station towards Pasir Ris station. By 8.24pm, the fault had been cleared, according to a post on SMRT’s Twitter page.

The 2nd fault happened at about 5.33am on Friday, and halted services between Outram Park station and Aljunied station.


East-West Line experienced fault three times in less than 24 hours

Singapore Mass rapid Transit (SMRT) has announced this early morning (23 December) that there was no train service between Outram Park and Aljunied on its East-West Line (EWL) due to a traction power fault near Bugis.


These delays meant that there were three delays along EWL in less than 24 hours. The first one occurred last night from Outram Park station to Eunos station towards Pasir Ris due to track fault and passengers were asked to add 15 minutes of additional travelling time.


Many of the commuters went to social media to express their disappointment. Many of them said that it was not only ten minutes delay as they got stuck at least 20 minutes. Some even said it was more than 40 minutes delay.


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Mysterious signal fault returns to cause disruption on Circle Line

The crowds at Bishan station on the Circle Line. Foto: shark_kul/Twitter

A mysterious signal fault on the Circle Line has returned to frustrate commuters, with travel times delayed by at least half an hour during the morning rush hour on Wed (Nov 2).

The CCL last saw a signal fault on Aug 29, when commuters were hit 5 days in a row with delays that SMRT attributed to the signaling fault.

SMRT has been trying — unsuccessfully so far — to identify the source of the problem, including shutting off mobile phone signals on Sep 2.

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Circle Line hit by third MRT signalling fault in 4 days

Train services on the Circle Line slowed to a crawl during the rush-hour commute yesterday, as another signalling fault — the 3rd in 4 days — hit the MRT network.

Operator SMRT said train services on the line were affected between 6am to 9am yesterday, after a defective signal connector was found between Mountbatten & Stadium MRT stations. This added about 20 minutes of travelling time for commuters, as trains ran at slower speeds and SMRT engineers tried to rectify the fault. SMRT spokesperson Alina Boey said additional trains were deployed to cope with the crowd build-up along the line.

On Monday, a track circuit failure between Yew Tee and Kranji stations caused trains to slow down, resulting in commuters being late for work and school. The affected commuters included some Republic Polytechnic and Nanyang Polytechnic students who were late for their examinations.

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3rd service disruption on SMRT this week caused by signal fault


A signal fault on SMRT's Circle Line on Thursday morning caused another service disruption -- the 3rd this week alone. SMRT tweeted at 7:36am that a signal fault would cause an additional delay of 20 minutes travelling time from Paya Lebar to Dhoby Ghaut. At 8:53am, it tweeted that train services between the two stations were operating normally again.

On Wed, an SMRT spokesman said that the upgrading programme to update the signalling system across the entire SMRT network would take up to two years, and warned commuters that delays would continue in the meantime. She said it would eventually "address many of the signalling-related incidents we are facing today". On Tuesday, another track fault struck the North-South Line, causing passengers to suffer delays a day after thousands of commuters saw their travel disrupted in the morning rush hour on Monday.

The latest disruption lasted about half an hour and affected south bound services between Ang Mo Kio and Marina Bay stations.

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'Intermittent signal interference' causes delays, train disruption on Circle Line during morning peak hour
A signal fault caused delays and long commuter queues at stations along the Circle Line. FOTO: @SHARK_KUL/TWITTER

Commuters were left frustrated after a signal fault caused significant delays on the Circle Line (CCL) on Wed (Nov 2) morning.

The fault, described by operator SMRT as an "intermittent" one, culminated in the disruption of train service between Botanic Gardens & Marymount MRT stations in both directions at around 9.10am. The disruption later extended beyond Marymount to Serangoon station.

Free regular bus services were also made available at all stations along the line.

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Circle Line signal fault that caused train disruptions on Wednesday morning similar to September delays: LTA, SMRT

The signalling interference that caused train service disruptions on the Circle Line (CCL) on Wednesday (Nov 2) morning could be similar to the week-long series of mysterious delays that plagued the same MRT line in September.

A joint statement by the Land Transport Authority (LTA) and CCL operator SMRT on Wednesday afternoon said preliminary investigations indicate the possibility of an interfering signal that could have disrupted communications.

Should similiar signalling faults occur, LTA and SMRT said they have arranged with the Infocomm Media Development Authority (IMDA) and mobile network operators to suspend telecommunication signals along stretches of CCL for short periods of time to assist in investigations.

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LTA may cut mobile network signals along Circle Line while investigating signalling faults


It's been a troublesome past few weeks for Circle Line operators SMRT, and even more vexing for the commuters who've been affected by service delays. Longer waiting times and slower trains have hit the underground MRT line four times in the last 3 weeks, and most of them occurring in the rush hours.

The worst of it took place yesterday morning, when delays stretched up to 4 hours as disruptions affected the line from Serangoon to Botanic Gardens MRT stations. One commuter even claimed that a lady fainted when everyone got stuck in the train, with no ventilation and non-functioning air-conditioning.

Investigations conducted by the Land Transport Authority (LTA) and SMRT determined that an interfering signal could have disrupted the communications, thus leading to signalling faults that've caused the delays. They've yet to establish the source of the interfering signals for now.

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Signalling faults disrupt NEL services

The crowd inside Hougang MRT station (left) at 10.24am yesterday. SBS Transit said service resumed at 10.28am – nearly 3½ hours after the first glitch occurred

About 35,000 commuters on their way to work just after 8:00am yesterday were hit by a major breakdown on the North East Line (NEL).

It was the 4th incident that lasted more than 30 minutes this year on the 12-year-old line.

Operator SBS Transit said a signalling glitch at 7:08am affected service between Sengkang and Punggol stations. It was fixed at about 7:20am.

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Unprecedented train disruption along 4 lines caused by power dip, says SMRT
Commuters on the platform at Jurong East MRT station last night. The screen shows a notice about the disruption in train service. FOTO: DIOS VINCOY JR FOR THE STRAITS TIMES

A power fault triggered an unprecedented breakdown of train services along 3 MRT lines and one LRT line last night, disrupting the journeys of thousands of commuters near the end of the evening peak.


The trip, which occurred at 7:53pm, also led to blackouts and a loss of air-conditioning at all affected stations. They were without power except for emergency lighting.

Train services were unavailable for between 30 minutes and 2 hours, and free bus shuttle services were deployed.

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Faults affect Circle Line for whole day


Rail operator SMRT was unable to fix a signalling fault that affected service on the Circle Line for the whole of yesterday.


The glitch, which the operator described as "intermittent signalling issues", slowed train speeds and reduced service frequency during the morning peak period.

Commuters took to social media to complain of packed stations. Other users tweeted that faulty sensors were causing train doors to shut on commuters.

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Train delay on East-West line due to signalling fault at Aljunied
Commuters were advised to "add 20min travel time between Pasir Ris and Outram Park", on Wed morning (Dec 14). ST FOTO: MELISSA LIN

Train services on the East-West line were delayed on Wednesday (Dec 14) during the morning peak due to a signalling fault at Aljunied MRT Station.

SMRT in a tweet at 8.39am advised commuters to "add 20min travel time between Pasir Ris and Outram Park".

It added that "train services are still available", but advised commuters to refer to bus guides on its site for more details.

Commuters reacted angrily online, with some saying they had been stuck for longer than 20 minutes; others reacted in disbelief at the frequency of breakdowns.

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Signal interference issue plagues Circle Line again

The crowd at Bishan MRT station this morning. foto: n1veda/Tiwtter

A signal interference problem that disrupted train services for 5 days in August and September returned on Wednesday (Nov 2) during the morning rush hour, leaving six Circle Line (CCL) stations, including major interchanges like Bishan and Serangoon, without train service.


The interference caused loss of signal between trains & stations, forcing the trains to come to a stop.


The Land Transport Authority (LTA) and SMRT on Wed said that preliminary investigations indicate that the nature of the faults in the latest incident could be similar.


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Railway signalling


Railway signalling is a system used to direct railway traffic and keep trains clear of each other at all times. Trains move on fixed rails, making them uniquely susceptible to collision. This susceptibility is exacerbated by the enormous weight and inertia of a train, which make it difficult to quickly stop when encountering an obstacle. In the UK, the Regulation of Railways Act 1889 introduced a series of requirements on matters such as the implementation of interlocked block signalling and other safety measures as a direct result of the Armagh rail disaster in that year.


Most forms of train control involve movement authority being passed from those responsible for each section of a rail network (e.g., a signalman or stationmaster) to the train crew. The set of rules and the physical equipment used to accomplish this determine what is known as the method of working (UK), method of operation (US) or safeworking (Aus.). Not all these methods require the use of physical signals, and some systems are specific to single track railways.

The earliest rail cars were first hauled by horses or mules. A mounted flagman on a horse preceded some early trains. Hand and arm signals were used to direct the “train drivers”. Foggy and poor-visibility conditions gave rise to flags and lanterns. Wayside signalling dates back as far as 1832, and used elevated flags or balls that could be seen from afar.

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Full Coverage:

Circle Line signalling problems caused by intermittent
Information Kit - SMRT Corporation
Circle Line hit by third MRT signalling fault in four days
Mass Rapid Transit (Singapore)
Railway signalling - Wikipedia
SMRT | Facebook
Mystery of Circle Line's signalling problem solved
Special report: Obsolete MRT signal system could lead to
MRT: Use proven method of predicting system failures
Circle Line signal fault that caused train disruptions on
Signalling faults disrupt North-East Line services
LTA may cut mobile network signals along Circle Line while
We’re working on it! – SMRT Blog
Service Enhancements - SMRT Corporation
Signalling faults disrupt NEL services, General, News
Train delay on East-West line due to signalling fault at
Signalling faults cause delays along Circle Line | TODAY
Mobile signals may be cut to probe Circle Line disruption
Unprecedented train disruption along 4 lines caused by
MRT services delayed due to 3 disruptions, Singapore News
MRT & LRT News and Updates - MRT Singapore (MRT.SG)
Circle Line breakdown caused by power supply failure: SMRT
Third service disruption on SMRT this week caused by
MRT Disruption Feed | Facebook
Faults affect Circle Line due to "intermittent signalling
Circle Line hit by third MRT signalling fault in four days
Train delay on East-West line due to signalling fault at
Signalling faults cause delays along Circle Line
Mobile signals may be cut to probe Circle Line disruption
Circle Line train service resumes after 3-hour delay
Signal interference issue plagues Circle Line again
Faults affect Circle Line due to "intermittent signalling
Circle Line signal fault that caused train disruptions on
MRT & LRT News and Updates - MRT Singapore
Train Service Improvements: Better Reliability and More


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