Unfinished maintenance work causes 4-hr delay on N-S Line
Track maintenance works which could not be completed before train operation hours caused delays on the North-South MRT Line for four hours yesterday morning.
It was the second such incident in a week on the heavily used line, which had a relatively trouble-free January after a host of problems last year.
Just before 6am yesterday, SMRT announced through Twitter and Facebook that city-bound trains were travelling slower because of "maintenance work".
Journeys would take 20 minutes longer, SMRT said. Normal service resumed at 10am.
Ongoing track improvement work had also caused delays, of between five and 10 minutes, on Feb 7.
On yesterday's delays, SMRT Trains chief maintenance officer Chia Chun Wah said the operator had to cast fresh concrete on a track bed which supports the rails near Raffles Place, to replace the worn parts of a concrete track slab.
Unlike surface tracks, which rest on individual sleepers, underground tracks sit on sleepers which are embedded in concrete slabs. When these are worn or damaged, they have to be hacked away and recast.
Mr Chia said the fresh concrete requires "several hours" to fully cure.
To facilitate the curing process, SMRT put in place additional support structures and imposed a further speed restriction over a 300m stretch.
The speed restriction caused trains to bunch up along the line during peak periods.