T26 defective trains will have their new bolsters cast by Japanese supplier Kobe Steel

As the trains are still under warranty, shipping and rectification costs are borne by the supplier.

The trains were ordered in 2009.

The hairline cracks were found during routine inspection in 2013, more than 2 years after the trains were put into service and after they had each clocked an average of 300,000 km.

Computational tests found that despite the defects, the bolsters could still withstand pressure loads of more than three times the maximum measured levels on the system.

Kawasaki Heavy Industries, part of the Japanese-Chinese consortium that won the contract in 2009 to supply the trains is the lead contractor responsible for the design and procurement of parts such as the brake.