Written Reply by Minister for Transport Khaw Boon Wan to Parliamentary Question on Resolution of Signalling Problems Along Circle Line

Mr Dennis Tan Lip Fong asked the Minister for Transport in respect of the recent signalling problems with the Circle Line caused by signal interference, what measures will be taken to ensure that commuters are not inconvenienced by the same signalling problems again.

Reply by Minister for Transport Khaw Boon Wan:

1.     The signalling problem experienced on the Circle Line was caused by a hardware malfunction on one of the trains. The faulty component has been replaced and the train has since been returned to service under close supervision. The Land Transport Authority (LTA) is working with the signalling equipment manufacturer ALSTOM to determine why the component failed, and whether the problem extends to the entire batch of components manufactured. If so, LTA will require ALSTOM to replace all of them.

2.     Based on the findings, LTA will also develop targeted measures to prevent an occurrence of similar problems on both the Circle Line and North-East Line, which use older signalling systems. LTA is also exploring ways to improve the general resilience of these systems. This includes shielding the signalling antenna against spurious signals, incorporating a feature for a backup antenna if the primary one encounters interference, and improving the signal transmission protocol.

3.     The newer signalling systems used for the Downtown Line, and to be installed for the North-South and East-West Lines and the Thomson-East Coast Line, would not be affected by the signalling problem experienced by the Circle Line as they have enhanced redundancy features to guard against signal interference.