The Land Transport Authority (LTA) announced today that no action will be taken against SBS Transit, which operates Singapore's North-East Line (NEL) for the seven-hour service breakdown that occurred on July 24 last year.

Extensive investigations by the LTA revealed that a faulty porcelain insulator which supported the provision of electricity to the train had resulted in a "loss of traction power".

The defective insulator has since been declared a one-off exception, and SBS Transit has promised more stringent checks to be conducted once every two months.

The French supplier of the porcelain insulators, Ceralep Sn, has also certified that the remaining parts in the operator's stock are defect-free.

Findings from LTA's investigation were verified by independent assessor, TV SD PSB Corp Pte Ltd.

The North East Line is a fully automatic underground heavy rail system which was built at a cost of $4.6 billion. It has a total of 16 stations, and is 20 km long. Up to 300,000 commuters use the NEL rail system daily.