Singapore Mass Rapid Transit (SMRT ) and Land Transport Authority (LTA) have just announced that their preliminary investigations into the major service disruption on the Circle Line (CCL), Wednesday (2 November) could be similar to that of the incidents in September this year and said that temporary telecommunication signal suspensions to be carried out to assist in investigations.
CCL experienced intermittent loss of signalling-related communications this morning that led to multiple delays of train services at various locations within the network. Preliminary investigations by LTA and SMRT indicate that the nature of the faults could be similar to that of the incidents that occurred on the CCL in September this year.
SMRT and LTA state that investigation into those incidents assessed that an interfering signal could have disrupted the communications. The source of the interfering signals could not be conclusively established as the incidents subsequently stopped.
Following the CCL incidents in September, LTA and SMRT had commenced feasibility studies to strengthen the existing signalling communications network, for example, explore placing an electromagnetic shield on the train to minimise the impact of interfering signals, and changing the signal system frequency and/or modifying the system to provide redundancy in the event of signal interference.
SMRT and LTA state that this led to the build-up of commuters at affected stations as SMRT staff were making their way to the stalled trains to manually drive them to station platforms.
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.
LTA and SMRT 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, should similar signalling faults recur. If temporary telecommunication signal suspensions have to be carried out, there will be in-train and station announcements along the affected stretches.
Earlier on 2 September, mobile networks for CCL was momentarily shut down for the investigation of the intermittent signalling issues that have plagued the line for the entire week. However, the cause of the intermittent signal was not found during the tests.
The first service disruption along CCL occurred on Monday, 29 August. SMRT had asked commuters to hold onto handrail as the train may break suddenly due to the loss of communication signal. The fault lasted for five consecutive days due to intermittent signaling issues.