A series of unresolved cable faults which had beset the Tuas West Extension since it opened in 2017 led to the massive three-line MRT breakdown on Oct 14.

All the power cables on the extension will now be replaced. In all, French engineering group Alstom – which installed the power lines – will replace 150km of cables with new ones of a higher quality.

The decision came after a section of cables burnt through on Oct 14. The failure would have been isolated by circuit breakers in the area – as was the case in four previous incidents. But on Oct 14, one failed to work. In fact, it melted from the heat.

Alstom will also replace 113 trip coils – the main component of circuit breakers – in this three-year-old extension of the East-West MRT line.

The move – which will involve early closures and late openings of stations over weekends up till the end of next year – is reminiscent of the re-cabling exercise for the equally new Circle Line.

In 2012, after repeated power-related train disruptions on the orbital line, the fault was traced to power cables – also installed by Alstom – which were exposed to water in the train tunnels.

The decision was made then to replace the cables, which usually last 20 to 30 years, with a more water-resistant type. The exercise, involving 120km of cables, was completed in 2014 for $15 million. Alstom was said to have borne the bulk of the cost.