The Circle Line (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. 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.
Since early September 2016, there has been no occurrence of similar signalling faults until this morning, which caused several trains to come to a stop between stations. 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.
We apologise to commuters who had their journeys affected this morning. Commuters are advised to refer to updates on LTA and SMRT website and social media platforms. Should there be further signalling faults, free bus boarding and bus bridging will be activated, and we urge commuters to seek alternative routes to get to your destination. We seek commuters’ understanding as we work to resolve the issue as quickly as possible.