CCL experienced signalling fault during morning rush hour (Source : da_salim Instagram account).

Khaw Boon Wan: Signalling problem experienced on Circle Line caused by hardware malfunction

Minister for Transport Khaw Boon Wan has stated that the signalling problem experienced on the Circle Line was caused by a hardware malfunction on one of the trains.

This is the response to a question filed by NCMP Dennis Tan Lip Fong who 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.

The Minister said that the faulty component has been replaced and the train has since been returned to service under close supervision.

He noted that 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.

Based on the findings, Mr Khaw said that 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.

He then added that 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.

CCL had a couple of signalling fault earlier last year, mainly during morning rush hour, causing commuters to have to wait for hours. The worst occurred in September when the line had the disruption for five days in a row.

Subsequently,  LTA announced that the investigation has traced the source of the signalling problems which plague the CCL to an intermittent failure of the signalling hardware on one train – Passenger Vehicle 46 (PV46).

A joint team comprising LTA, Singapore Mass Rapid Transit (SMRT), the CCL signalling system manufacturer Alstom, the IMDA, DSTA, DSO National Laboratories, GovTech and electro-magnetic interference specialist Rohde & Schwarz found that the intermittent hardware failure had caused about 100 occurrences of loss of signalling communications on trains travelling in the proximity of PV46 between 2 to 6 Nov 2016.