The track fault that delayed services on the North-South Line on Wednesday morning was caused by a short circuit between two track blocks, said operator SMRT.
The operator said preliminary investigations found that the short circuit was caused by a foreign metal object measuring 2cm in length that its engineers found on the insulated rail joint located on the running rail connecting the two track blocks.
This activated an automatic safety mechanism which prevented other trains from entering the affected sector as the system indicated that the track towards Marina Bay was occupied.
This caused the delay between Raffles Place and Marina Bay stations. SMRT said it is conducting a thorough investigation into the incident.