[Updated on 10 November on Transport Minister's comments on the disruption]
[Updated on 4 November on telco services being suspended on Friday 4 November amid tests for signal fault]
Singapore's Land Transport Authority (LTA) and SMRT have arranged with the Infocomm Media Development Authority (IMDA) and mobile network operators to suspend telecommunication signals along stretches of Circle Line (CCL) for short periods of time, if signaling faults were to occur again.
This is to assist in investigating the cause of the faults.
If temporary telecommunication signal suspensions have to be carried out, there will be in-train and station announcements along the affected stretches, LTA and SMRT said in a joint statement on 3 November 2016.
The CCL experienced intermittent loss of signaling-related communications on the morning of 3 November. This led to multiple delays of train services at various locations within the network.
As a precautionary measure, all CCL trains will be manned during evening peak hours for faster response and recovery. SMRT will also deploy additional manpower at train stations to assist commuters.
Primary investigations by LTA and SMRT indicate that the nature of the faults could be similar to those that occurred earlier this year in September. Investigations into those incidents assessed that an interfering signal could have disrupted the communications.
Follow the incidents in September, LTA and SMRT had commenced feasibility studies to strengthen the existing signaling communications network.
For example, they have explored placing an electromagnetic shield on the train to minimise the impact of interfering signals. They also changed the signal system frequency and/or modified the system to provide redundancy in the event of signal interference.
Mobile services along the entire CCL was shut for a full day on Friday (Nov 4), as the authorities escalated efforts to track down the source of a persistent signal fault that's been causing widespread delays.
Telcos M1 and Singtel first announced a suspension of telecommunication signals on the 30-station line for about two hours on Friday morning.
Friday's shutdown of mobile telecommunication signals on the CCL is the second in two days and the most drastic yet by the authorities.
They had previously ordered a smaller-scale suspension of mobile signals on Sept 2, in a similar bid to trace the source of the interfering signal, which resulted in train service delays spanning five days.
Singapore government to reveal cause of disruption soon [Updated 10 November]
The Singapore Government is expected to make known the cause of the signalling interference that has repeatedly tripped up train services on the CCL in recent months, Transport Minister Khaw Boon Wan said in Parliament on 8 November 2016.
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