SINGAPORE – The North-South MRT line incident on June 3, which led to huge crowds forming at affected stations and bus stops, is the first train disruption caused by a lightning strike here in the past five years, said Transport Minister Chee Hong Tat.
As the section of track between Kranji and Marsiling stations is lightning-prone, past lightning strikes may have sped up the deterioration of a surge arrestor that failed to work that day, leading to a loss of traction power along the northern section of the MRT line, the minister added.
Giving more details about the incident in a written parliamentary reply on July 2, Mr Chee said the surge arrestor in question has been replaced, and checks have found that the other surge arrestors in the vicinity are in working condition.
He said rail operator SMRT had adhered to the maintenance regime recommended by the manufacturer of the component, but arising from the June 3 incident, the authorities are working with the manufacturer and the rail operators here to review the maintenance frequency.
“The current lightning protection systems for our MRT network comply with local and international standards, to ensure the safety of our commuters,” Mr Chee added in reply to questions filed by Mr Alex Yam (Marsiling-Yew Tee GRC) and Mr Melvin Yong (Radin Mas).
It was the Land Transport Authority (LTA) that traced the train service disruption between Choa Chu Kang and Woodlands stations to the malfunctioning surge arrestor, which was located in an outdoor trackside power control box near Kranji station that was damaged by the lightning strike on June 3.
The surge arrestor was meant to protect the power control box from electrical surges, like those from lightning strikes, but it did not work as intended.
A small fire broke out in the power control box and numerous components were damaged, especially the disconnecting switch – a device that ensures energy is not running through a circuit so that it is safe to conduct emergency stoppages, repairs, maintenance or inspections.
SMRT engineers had to physically access the power control box on the MRT viaduct to isolate it before power could be restored to the rail.
In its assessment of the disruption, which lasted more than two hours during the evening rush hour, LTA said on June 15 that the condition of the surge arrestor could have deteriorated over time, but it did not provide more details.
SMRT later clarified on June 18 that the surge arrestor was new and commissioned as part of a decade-long, $2.6 billion renewal programme by the LTA for the ageing North-South and East-West lines.
The new component, made by German company Kraus Elektrotechnik, was handed over to SMRT seven months before the disruption, and it was not due for servicing until 2025, the rail operator had said in response to queries from The Straits Times.
Mr Chee said in his written parliamentary reply on July 2 that the investigation into the June 3 disruption is continuing.