SINGAPORE, July 6 -- Hairline cracks found on the China-made MRT trains were due to localized impurity in aluminium car-body material that occurred during manufacturing process, said Singapore's Land Transport Authority (LTA) in a press release on Wednesday.

Local media reported earlier that hairline cracks were found on 26 out of 35 trains, which were manufactured by Kawasaki Heavy Industries and China Southern Railway Sifang and then delivered to Singapore's Mass Rapid Transit (MRT) operator SMRT. Since the news came out, defective trains has become the subject of recent media and online discussion.

LTA on Wednesday noted that laboratory tests showed hairline cracks on the surface of the car-body bolster were due to localized impurity in the aluminium car-body material that occurred during the manufacturing process. Since the cracks were found, LTA immediately carried out further inspections.

LTA engineers and its contractor assessed that the hairline cracks would not affect the operational safety of the trains. Besides, an independent third-party assessor also said the trains were safe to operate.

"To confirm this, LTA further sought the opinion of an independent third-party assessor, TUV Rheinland, which concurred that the trains were safe to operate." stressed LTA.

As the best fix for the cracks was to replace the entire car-body shell, the affected trains have been progressively sent back to the factory for rectification works, according to LTA's press release.

The authority has also been working closely with SMRT to ensure that this unexpected occurrence did not affect the train deployment. The car-body replacement for five of the 26 trains has been completed so far. The car-body of the sixth train is being replaced. The rectification program will be completed in 2019.

LTA added they, together with the contractor, will continue to carry out rigorous inspections to ensure all trains are safe for service.

The public transport operator SMRT on Wednesday also stressed that the decision to send the defective trains back to the manufacturer for repairs will not affect train service availability or frequency in its latest media release. Enditem