Turkish newspapers report that the segments used in İzmir Metrosu Narlıdere extension construction crack. Newspapers say the contractor Gülermak use Fiber Reinforced Polymer and Macro Synthetic Fiber in segments instead of steel bars.

Because of this the controller company müşavir UBM (Uluslayrarası Birleşmiş Müşavirler Müşavirlik Hizmetleri A.Ş) summons the main contractor Gülermak for an emergency meeting. At the 18 July meeting, UBM tells Gülermak to use segments with steel bars. It is not clear what will happen to segments already placed in the tunnel.

The Narlıdere metro tunnel is alongside the İzmir bay and known to have a muddy composure.

Turkish newspaper:

https://www.yeniasir.com.tr/izmir/2019/08/29/metronun-tunel-kaplamasi-catladi