Reasons behind NEL disruptions in October revealed

SWITCHGEAR malfunction and damage from sustained arcing were behind the two disruptions on the North-east Line (NEL) last month.

The Land Transport Authority (LTA) and SBS Transit (SBST) announced this on Friday after completing their investigations into the causes of the rail service disruptions on the SBST-operated NEL which occurred on Oct 13 and 26, 2015.

Both incidents took place during the morning peak period. The Oct 13 disruption was for more than one and a half hours, accompanied by blackouts at several stations.

The Oct 26 episode was more severe, lasting almost two hours and affecting some 41,000 commuters, including students sitting their O and A level exams.

On Oct 13, NEL train services were disrupted between Farrer Park and Hougang stations due to a power fault triggered by a malfunction of a component in the electrical switchgear at a substation supplying electricity to the trains. This caused the main circuit breaker to trip. As a result, power was diverted to a backup breaker which also tripped.

As for the Oct 26 disruption, a new train undergoing testing damaged the overhead catenary system (OCS) when it was returning to the depot on one of the reception tracks. Power to the mainline tracks was switched off to facilitate urgent repair works, thereby affecting the launching of trains to the mainline and disrupting NEL services.