Cracks in 26 defective SMRT trains due to 'localised impurity': LTA

SINGAPORE - The hairline cracks found in 26 defective China-made SMRT trains "were due to localised impurity in the aluminium car-body material that occurred during the manufacturing process", the Land Transport Authority (LTA) disclosed on Wednesday night.

In a statement, the LTA provided a timeline of events leading up to the recent return of the defective trains to its Chinese manufacturer CSR Sifang, an illustration showing where the cracks occurred, and a sample photo of the hairline cracks first discovered in July 2013. 

LTA also confirmed that 22 of the 26 defective trains were in service then. But no further cracks were found on other components of the trains after inspections, beyond those discovered on the surface of the car-body bolster, which is on the undercarriage of the trains. The LTA reiterated its earlier assurance that its own tests, as well as that by a third-party assessor, found the trains to be safe to operate despite the discovery of the cracks.

Defects were also found in the trains before they were progressively put into service from February 2011. According to the LTA, the train's manufacturer had to replace a supplier and "improve the design of the battery housing for all affected trains" after an incident where the cover of a train's battery housing flew open after a build-up of gases. Another defect involved cracks on the draughtscreen of five trains. These cracks were caused by errors during the installation process, and were unrelated to the hairline cracks subsequently found on the 26 defective trains, LTA said.

It added: "It is not unusual to detect some defects on new trains. We then take appropriate action to have them rectified by the manufacturer."

In a separate statement on Wednesday night, SMRT spokesman Patrick Nathan said "passenger safety is paramount to SMRT, and under no circumstance will this be compromised". But the train operator shed no new light on the issue, and did not address allegations by a Hong Kong investigative report that the trains were being "secretly" shipped back to China.

News of the defective trains first broke on Tuesday when FactWire, a crowd-funded investigative journalism site, released an extensive report with photos and video footage of several trains being shipped out of SMRT's Bishan depot for Jurong Port, before being transported to China.

The trains in the spotlight are the C151A-model trains supplied by Japanese train-maker Kawasaki Heavy Industries and the China-based CSR Sifang. The two firms, together with Kawasaki’s Singapore subsidiary, had bagged a S$368 million contract in 2009 to supply 22 six-car C151A trains meant for the North-South and East-West Lines (NSEWL). SMRT subsequently ordered another 13 trains of the same model.

In 2014, the same consortium was also awarded a S$749 million contract to supply 91 new four-car trains — of a different model — for the Thomson-East Coast Line.

According to LTA's account of events, the hairline cracks on the car-body bolster of the 26 defective trains were discovered during a routine inspection in July 2013. Upon further inspections, no cracks were found on other parts of the trains.

Laboratory tests found that the hairline cracks were due to "localised impurity in the aluminum car-body shell", though the LTA's engineers and contractor found that the cracks "would not affect the operational safety of the trains". LTA said an independent assessor, Cologne-based TUV Rheinland, agree with its assessment.

The defective trains were still under warranty, and LTA said it told the contractor to replace the entire car-body shell - the most effective way of addressing the problem of hairline cracks.

The defective trains have been sent back to China for rectification works since July 2014. But only one train was sent back to the mainland factory at any one time, the LTA said, due to the time consuming process - each car-body replacement took up to four months - as well as the need to minimise the impact on train operations in Singapore.

LTA added: "To minimise the impact on our train operations in Singapore as well as the lack of facilities and space for repair works of this nature at our depots, only one train is sent back to the factory in China at any one time. We did not send all of the trains back at once as they were still fit and safe for service and we wanted to ensure sufficient train-availability for commuters."

But from next year, the LTA expects to be able to send two defective trains for replacement works at a time. This is due to the arrival of new trains for the NSEWL, and also because trains currently undergoing re-signalling are expected to be ready by then.

This will bring forward the completion date of the repairs to 2019, the LTA added. SMRT previously said the replacement works would be finished only in 2023 - a time frame that transport analyst Park Byung Joon described as “an awfully long time”.

So far, five of the 26 affected trains have undergone repairs and have been brought back into service. The car-body of a sixth train is currently being replaced. The other trains are still running before being sent for repairs to minimise disruption to train operations, with the LTA reiterating that they are “safe for service”.

The NSEWL have been plagued by a litany of woes in recent years. Last year, services on both lines came to a complete standstill for several hours in an unprecedented incident. In 2011, a massive breakdown during the evening rush hour affected 127,000 commuters at 11 MRT stations on the North-South Line.