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Signalling system not at fault for DTL service disruption: Siemens

SINGAPORE — A day after the Downtown Line (DTL) was hit by a seven-hour delay, Siemens said on Thursday (May 4) the signalling system it supplied was not to blame for the fault which caused platform screen doors at Botanic Gardens to malfunction.

Two platform doors cordoned off at Downtown line train platform towards Chinatown station, at Botanic Garden station, on May 3, 2017. Photo: Robin Choo/TODAY

Two platform doors cordoned off at Downtown line train platform towards Chinatown station, at Botanic Garden station, on May 3, 2017. Photo: Robin Choo/TODAY

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SINGAPORE — A day after the Downtown Line (DTL) was hit by a seven-hour delay, Siemens said on Thursday (May 4) the signalling system it supplied was not to blame for the fault which caused platform screen doors at Botanic Gardens to malfunction.

Responding to TODAY’s queries, Siemens said it was supporting rail operator SBS Transit in its investigations and “can already confirm that the root cause is not linked to Siemens”.

However, when contacted, the operator and the Land Transport Authority (LTA) told this newspaper that the cause of the incident has not been ascertained and will require further investigation. They added that one of the two affected doors has been repaired and in operation since the start of passenger service on Thursday morning. Repair work on the second door was scheduled to be carried out after passenger service hours on Thursday.

On Wednesday, city-bound trains on the DTL hit a snarl between 5.45am and about 1pm, the longest trip-up to date to hit the four-year-old rail network. Not only did stops at each station last longer, but trains skipped the Botanic Gardens Station owing to what SBS Transit had described as a “signalling-related fault” which resulted in platform doors failing to open automatically.

When contacted, the supplier of the platform doors, Faiveley Transport, declined comment, referring TODAY to the LTA.

The signalling system on the DTL — called the communications-based train control system — is the same one being tested on the SMRT-run North-South Line (NSL). Plans are also in the pipeline to roll out the system on SMRT’s East-West Line. During earlier trials on the NSL’s new signalling system — which is supplied by Thales — doors had failed to open and shut automatically at times, owing to a software bug. Thales was unable to comment when contacted by TODAY.

Commenting on Wednesday’s incident on the DTL, Assistant Professor Andrew Ng, a railway signalling, control and communications lecturer at the Singapore Institute of Technology, said that if the signalling system was not to blame, malfunctioning electrical circuits or mechanical components in the platform doors could have caused them to stop opening.

Platform doors, he added, run on an interlocking system comprising electro-mechanical or electronic switching devices typically housed in signalling equipment rooms. The system serves as a safety feature that ensures doors open only when trains are in position at the platforms, for instance.

He said the incident could have been due to faulty interlocking switches that failed to activate the platform doors. Only when all the relevant interlocking switches are functioning will the doors open automatically, Asst Prof Ng said.

Wednesday’s incident marked the second time in seven months that the line experienced delays for hours owing to a problem with the platform doors. In October last year, services were disrupted for about two hours after a platform door became dislodged at Sixth Avenue Station because of a loose bolt.

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