The Land Transport Authority is planning to install an electromagnetic shield on MRT trains after a mysterious signal interference disrupted service on the Circle Line three weeks ago.
Electromagnetic shields are used in secured facilities, high-tech laboratories or on sensitive electronic equipment to protect them from possible outside interference.
In a joint statement with operator SMRT Corp issued yesterday, LTA said it will soon start feasibility studies on ways “to strengthen the existing signalling communications network” .
It will also explore the possibility of changing the signal frequency of the network.
Separately, it will look at modifying the system “to provide redundancy in the event of signal interference”.
The LTA noted that the signalling systems on newer lines such as the Downtown Line and current lines undergoing upgrading such as the North-south and East-west Lines “are already equipped with new features that provide redundancy in the event of signal interference”.
The five-year-old Circle Line and the 13-year-old North-east Line, however, do not have these features.
In the interim, spectrum analysers – which can detect stray transmissions – will be installed in the Circle Line tunnels.
“This measure will be extended to the North-east Line, which has the same signalling system,” the joint statement read.
The Circle Line was hit by a signal interference between Aug 29 and Sept 2. The undetermined source apparently interfered with communication between trains and the track, causing trains to apply emergency braking intermittently.
This led to longer and jerkier journeys for a week.
The problem stopped as suddenly as it started.
Together with systems supplier Alstom of France, the LTA and SMRT have been trying to get to the root of the problem.
“Over the past two weeks, engineers have tried to establish the source of the interfering signals,” the joint statement said.
“However, as the incidents had ceased by the afternoon of Sept 2, they were unable to determine the source.”
christan@sph.com.sg
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