An interfering signal in the Circle Line tunnel, within the operating frequency band of the trains' signalling system, could be the cause of disruptions to normal train service in the past week, SMRT and the Land Transport Authority (LTA) announced in a joint statement on Saturday (Sep 3).

SINGAPORE: An interfering signal in the Circle Line tunnel, within the operating frequency band of the trains' signalling system, could be the cause of disruptions to normal train service in the past week, SMRT and the Land Transport Authority (LTA) announced in a joint statement on Saturday (Sep 3).

The interfering signal could be a possible cause of the intermittent loss of train-to-track communications but experts have not yet been able to verify the source, SMRT and LTA stated. The Circle Line has seen trains slowing down during peak hours for five consecutive days, due to issues with the signalling system.



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On Friday, SMRT announced it would switch off mobile signals at four Circle Line stations for two hours the same evening, “to eliminate telecommunication signals as a possible cause” and more tests were also conducted throughout the night between 1 am and 4 am.



“However, as there was no incident last evening, the tests were inconclusive. In fact, since 4 pm yesterday, there has not been any intermittent loss of signal communication of train-to-track communications,” SMRT and LTA said.



The transport operator and the authority said investigations will continue. “Should and when an incident recur, SMRT and LTA have worked with the Infocomm Development Authority (IDA) and mobile network operators to suspend telecommunication signals along stretches of CCL for short periods of time for further tests. If temporary telecommunication signal suspensions have to be carried out, there will be in-train and station announcements along the affected stretches,” the statement said.