Avoiding another system-wide disruption

Avoiding another system-wide disruption_Header

The 7 July train disruption was a disaster because of its scale. Two major lines, the North-South and East-West Lines (NSEWL), were simultaneously affected. No service recovery plan can adequately address the sudden and large loss of supply in the public transport system.

The only way forward is to prevent a repeat. The question is how?

Friends who are engineers were puzzled why we built such a closely-linked system where a breakdown caused by a power fault on one line could trigger a failure on the other line. Surely, we must be able to contain any failures so as to reduce their impact?

Avoiding another system-wide disruption_PictureI put this question to LTA, who explained that the two lines were electrically linked to allow trains to move from the NSL to the EWL, and vice versa. The link was, and still is, essential as Bishan Depot on the NSL is the only depot across the two lines with heavy maintenance and overhaul capability. A decision was made in the early 80s to build only one such depot to minimise costs and land-take. (This limitation would disappear when the Tuas West Extension is completed next year, when we will have a depot on the EWL with similar facilities, at the Tuas West Depot.) Other than for maintenance, allowing cross-overs gives operational flexibility. Unfortunately, this also means that a power fault on one line could affect the other.

So what is the best way forward?

Our experts in LTA and SMRT have decided to delink the two lines electrically, by installing electrical breaks at Jurong East and Raffles Place Interchange stations. Under normal operations, these breaks will not be activated as we want to continue to have the flexibility between the NSL and EWL. But when the need arises, the two lines can be electrically disconnected. The electrical breaks will be fully installed by the end of next month. After that, a simultaneous breakdown of NSL and EWL, as happened on 7 July, can then be avoided.

Meanwhile, maintenance of all lines must be stepped up, to avoid any disruption. This is active work in progress.

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