Behind each MRT ride

How trains are overhauled and tracks maintained on North-South, East-West lines

- Esther Loi and Vanessa Paige Chelvan

Every four to five years, each of the 198 trains that operate on the North-South and East-West lines (NSEWL) is taken out of service for extensive maintenance that can take up to 21 days.

Typically, trains are overhauled for every 500,000km and 1,000,000km travelled, with different parts of the train restored at each mileage milestone.

At the 500,000km mark, parts such as the brakes and bogies—the undercarriage of a train—undergo servicing.

And at 1,000,000km, systems such as the door mechanism and couplers, which connect one carriage to the next, are thoroughly checked.

These are among as many as 13 major systems installed aboard a train.

SMRT said the maintenance intervals are determined by the respective manufacturers of the equipment. The operator's maintenance planners track the utilisation of every train and schedule it for overhaul, it added.

Every night, there are some 1,000 workers doing maintenance works on tracks, rail vehicles, facilities and signalling systems across 150 worksites, said SMRT.

This includes works related to system upgrades, as well as testing and commissioning, it added.