In an excellent article, Tunnel Business Magazine reports that, on July 24, 2020, a 26.2 feet (8.0 meter) ROBBINS successfully completed the boring of a 5.5 mile railway tunnel. The rock formation on the route of the tunnel for Bahçe-Nurdaği High-Speed Railway Tunnel is said to be among the hardest and most abrasive ever encountered in the country.

https://tunnelingonline.com/robbins-single-shield-breaks-through-turkeys-hardest-rock/